Protection of the yellow-spotted whiteface and the common

Transcription

Protection
of the
yellowspotted
whiteface
and the
common
spadefoot
toad
BEST PRACTICE
GUIDELINES
The experiences of LIFE-Nature
project “Securing Leucorrhinia
pectoralis and Pelobates fuscus in
the northern distribution area
in Estonia and Denmark”
LIFE08NAT/EE/000257 DRAGONLIFE
Protection of
the yellow-spotted
whiteface and
the common
spadefoot toad
Best Practice Guidelines
Best Practice Guidelines was made with the contribution
of the LIFE financial instrument of the European Community
LIFE08NAT/EE/000257 DRAGONLIFE
Compiled by
Riinu Rannap, Voldemar Rannap
Photos
Arne Ader, Christian Göcking, Kaili Viilma, Kristian Mantel, Lars Christian Adrados,
Lars Iversen, Laus Gro-Nielsen, Mads Fjeldsø Christensen, Marcus Held, Maris Markus, Martin Piechnik, Merike Linnamägi, Michael Bisping, Norbert Menke, Riinu Rannap,
Siim Veski, Voldemar Rannap, Wouter de Vries
Translated by
Pirkko Põdra
Layout
Eerik Keerend
Printed by
Print Best Trükikoda OÜ
Environmental Board of the Republic of Estonia
Tallinn
ISBN 978-9949-9606-7-5
content
DRAGONLIFE
Introduction 4
Project target species
8
The common spadefoot toad
Status of the common spadefoot toad in Estonia
Piret Pappel12
The common spadefoot toad in Denmark
Lars Briggs, Lars Chr Adrados, Niels Damm, Per Klit Christensen and Kåre Fog
16
Habitat requirements of the common spadefoot toad
Riinu Rannap, Tanel Kaart, Wouter de Vries, Lars Briggs, Lars L. Iversen
Criteria for the favourable conservation status of the
common spadefoot toad. Riinu Rannap, Wouter de Vries, Lars Briggs
Effects of habitat management on the common spadefoot toad
Riinu Rannap, Kadri Suislepp
Preservation of the common spadefoot toad in North
Rhine‑Westphalia. The experiences of LIFE project LIFE11NAT/DE/348
21
30
33
Christian Göcking, Norbert Menke
38
Status of the common spadefoot toad in the Netherlands
Wouter de Vries
45 Yellow-Spotted Whiteface
Habitat requirements of Leucorrhinia pectoralis
Lars L. Iversen, Riinu Rannap
54
Criteria for the favourable conservation status of
Leucorrhinia pectoralis Lars L. Iversen, Riinu Rannap
58
Effects of habitat management on Leucorrhinia pectoralis
Riinu Rannap, Lars L. Iversen, Timo Torp
61
4
Introduction
O
ne of the aims of the European Union is to
make sure that valuable rare and threat
ened species and habitats are preserved.
With their protection in mind, the Natura
2000 network was created. Through its various projects,
the European Union’s LIFE programme supports nature
conservation efforts in Natura 2000 sites.
The LIFE+ programme also supported the
DRAGONLIFE project, whose aim was to protect the
small and isolated populations of the dragonfly yellow
spotted whiteface (Leucorrhinia pectoralis) and the com
mon spadefoot toad (Pelobates fuscus) at the northern
edge of their distribution area and to ensure the favour
able conservation status of these species. In other words,
to contribute to increasing the numbers of these species
and to creating and maintaining viable populations in the
short and longer term.
The project joined partners from two countries: Esto
nia and Denmark. The coordinating beneficiary was the
Estonian Environmental Board. Associated beneficiar
ies were the Danish municipalities of Allerød, Gribskov,
Hillerød, Hjørring and Vejle and the Danish company
Amphi Consult.
The project lasted six years (2010–2015) and its budget
was 1,050,430 euros, half of which was provided by the
European Union’s LIFE+ programme and half by project
partners.
The protection of species is directly linked to the
protection of their habitats, i.e. the availability of suit
able habitats determines the survival of a species and the
viability of its populations. If habitats are destroyed, the
related species also disappear.
Both of the project’s target species, the common spa
defoot toad and the yellowspotted whiteface, need mosaic
terrestrial habitats, where meadows alternate with coppices
and small, traditionally cultivated fields with pastures.
Numerous small water bodies and wetlands (ponds, beaver
floods and small lakes) with clean water that form net
works with terrestrial habitats offer favourable breeding
conditions. However, many mosaic habitats of this kind
have been destroyed due to intensive agriculture (excessive
use of artificial fertilizers and pesticides), changes in land
use (massive monoculture fields taking the place of small
fields and garden plots) and the withering of traditional
country life (succession of abandoned areas). For example,
the extinction rate of small water bodies may amount to
as much as 50–90 % in Europe, depending on the country.
The remaining water bodies are often polluted, silted up or
stocked with fish, and therefore no longer suitable as habi
tats for many aquatic and semi-aquatic species. Because of
all these developments, many species, including the com
mon spadefoot toad and the yellowspotted whiteface, are
experiencing drastic decreases in numbers, considerable
shrinkage of distribution areas and fragmentation of the
remaining populations.
Introduction
The shortage of suitable breeding ponds and the
poor condition of surrounding terrestrial habitats also
determined the main species conservation efforts of the
project: creating and restoring ponds and cleaning up
the surrounding areas. Over the course of the project, we
restored and created 189 small water bodies in Estonia
and Denmark and cleaned up 50 ha of terrestrial habi
tats surrounding the water bodies. Although the project
actions were concentrated on the two target species, their
impact was far greater, as there are many other rare and
endangered species linked to small freshwater bodies with
high water quality, e.g. the green hawker (Aeshna viridis),
the great diving beetle (Dytiscus marginalis), the great
crested newt (Triturus cristatus), the moor frog (Rana
arvalis), etc. Thus, the project helped to improve the habi
tat conditions of all these species.
In order to find out what kind of water bodies the
common spadefoot toad and the yellowspotted whiteface
need, we inventoried in the project’s first year 270 small
water bodies in Estonia and 195 in Denmark. The inven
tory of small water bodies helped us to narrow down the
distribution of various species and the status of their pop
ulations as well as to determine the optimal parameters of
the water bodies for the target species to reproduce. The
inventory data was analysed and used for determining the
habitat requirements of the common spadefoot toad and
the yellowspotted whiteface and compiling the criteria
for the favourable conservation status of the two species.
In short, we found answers to the following questions:
what kind of water bodies these species need for breeding,
where should they be located, how should they be created
and when can we conclude that the status of a population
is favourable. The knowhow that was gained informed the
procedure of restoring small water bodies and managing
their surrounding areas in the years that followed.
In order to rescue Danish common spadefoot toad
6
populations located among intensively farmed fields or
in habitats in the process of growing over, we collected
common spadefoot toad spawn from the areas in question
and proceeded to grow the spawn in rearing stations. We
released 400 metamorphosed young individuals and ca
16,000 tadpoles in the final stages of development back
into nature. By the final year of the project, we were over
joyed to hear the calling of the first reintroduced common
spadefoot toads.
Keeping in mind the sustainability of project actions,
but also the future in a much broader sense, a significant
portion of the project actions was dedicated to educating,
training and teaching people. The activities were aimed
at diverse age groups (from students to adults) and target
groups (nature enthusiasts, landowners, nature conserva
tion specialists, local governments, community coopera
tion networks), and a variety of methods were employed
(TV and radio, the Internet and printed publications,
exhibitions and study trails, guided tours and training
days). All this was accompanied by a lot of talking with
local people and landowners when planning and carrying
out the work. The project yielded several folders on the
project and the target species, information boards, a study
trail and two permanent exhibitions, 49 training days
and four international seminars. We also put consider
Introduction
Project sites
Denmark
Estonia
1 Vandplasken
1 Lahemaa
2 Tinnet Krat
2 Mõdriku-Roela
3 Egtved
3 Varangu
4 Arresø
4 Neeruti
5 Kattehale Mose
5 Lasila
6 Gribskov
6 Porkuni
7 Karula
8 Emajõe-Suursoo
ja Piirissaare
able emphasis on international cooperation. Estonian
and Danish nature conservation staff and species experts
were joined at project seminars and in other activities by
experts from the Netherlands, the Czech Republic, Ger
many, Norway and Lithuania.
The project garnered a lot of media attention with the
publication of the Identification Key on Estonian Amphibians and the Identification Key on Estonian Dragonflies.
The former was accompanied by a mobile app, developed
in cooperation with the University of Tartu, and the latter
stood out as the first indepth publication on dragonflies
in Estonia in the past 50 years. Both publications, along
with the smart app, expanded the circle of amphibian and
dragonfly enthusiasts in Estonia almost explosively.
In order to ensure the sustainability of the measures
launched by the project, the common spadefoot toad and
the yellowspotted whiteface were provided with their
respective Estonian action plans for the next 15 years, and
After-LIFE Conservation Plans were drawn up for Esto
nian and Danish municipalities. Serving the same aim
are also these Best Practice Guidelines, which provide an
overview of the experiences and knowhow gained during
the project on the two target species – the common spade
foot toad and yellowspotted whiteface.
8
Project target
species
The Pelobates genus includes four species, three of which
are found in Europe. The species whose distribution area
extends farthest to the north is the common spadefoot
toad, Pelobates fuscus, the only representative of the genus
in Estonia and Denmark. Due to a shrinking distribution
area and loss of abundance caused by the destruction and
deterioration of habitats, the common spadefoot toad has
been listed in Annex IV of the European Union Habitats
Directive as a species in need of strict protection.
The common spadefoot toad is a small (up to 8 cm
long) amphibian with a round body. Its smooth gray skin is
covered with brownish spots. The common spadefoot toad
can be distinguished from other amphibians by looking
into its eyes: unlike other species, it has vertical pupils.
The common spadefoot toad has a terrestrial lifestyle,
using waters only for breeding. It leads a very hidden life,
digging itself into the ground during daytime and emerg
ing only at nightfall to search for food. The main prey for
food are ants, ground beetles, spiders and other nonflying
invertebrates. For digging, the toad uses the spade-shaped
tubercles on its hind feet. It only takes a couple of minutes
Pelobates fuscus
The yellow-spotted whiteface
for the toad to dig itself into the ground, posterior body
end first. Due to its burrowing lifestyle, the common spa
defoot toad prefers to live in places with light and grainy
soil: sandy areas, garden plots and small fields (cultivated
without artificial fertilizers or toxic substances).
In the spring, the toads head to puddles and ponds
to breed. The calling is not heard very far, as the males
call under the water, at the bottom of ponds. The mating
call resembles a silent knock. The spawn takes a string
like shape. Tadpoles take up to 100 days to reach the
metamorphosis stage. Prior to metamorphosis, the giant
tadpoles are up to twice the size of adult toads. Adult
common spadefoot toads hibernate burrowed in the
ground. Their lifespan is about 10 years.
mately 5 cm long. The abdomen of the yellow-spotted
whiteface is darkcoloured and there are yellow spots
on the backside. Males have the yellow spot only on the
seventh segment. In females, the spots are usually located
on the first seven segments, while the pattern on adult
females may resemble that of the males.
The yellowspotted whiteface lives near richly vegetated stagnant water bodies, small lakes and ancient
rivers. It is often found in beaver flood areas. The water
bodies and littoral zones need to have a diverse flora. Like
other dragonflies, the yellowspotted whiteface is an insect
of prey. It actively hunts the smaller insects flying over
the water. Once it has caught one, it lands on a plant and
devours the prey.
When mating, the males capture their partners in
the air. They then form a tandem of sorts and mate. Once
mating is complete, the male leaves and the female lays
the eggs into the water. The emerging larvae, or nymphs,
live in the water among the plants. The nymphs may live
in the water for up to three years, moulting around ten
times during this period. When they are ready to leave
the water, they crawl out up the stem of a plant and freeze.
After a while, a young dragonfly emerges from the skin,
stretching and drying its wings for a good while before
taking its first flight. The nymph skin, or exuvia, is left
behind on the plant stem. Adults perish at the end of
summer, and only the nymphs survive the winter at the
bottom of water bodies.
The yellow-spotted whiteface
The Leucorrhinia genus includes 16 dragonfly species,
five of which live in Europe. The genus is distinguished
by its white front, which has also inspired its name. In
Greek, leuco means “white” and rhinos “nose”, resulting
in the Latin name Leucorrhinia. The genus’ rarest species
in Europe is the yellowspotted whiteface, Leucorrhinia
pectoralis. Due to a shrinking distribution area and loss
of abundance, the yellowspotted whiteface has been listed
in Annexes II and IV of the European Union Habitats
Directive as a species in need of strict protection.
The yellow-spotted whiteface is a medium-size drag
onfly. It has a wingspan of 6–7 cm and its body is approxi
The common
spadefoot toad
Pelobates fuscus
12
Status of the common
spadefoot toad in
Estonia
Piret Pappel
The common spadefoot toad in Estonia
Figure 1. Common spadefoot toad distribution in Estonia in
2015. Light blue circles – studied water bodies in the historical distribution area without the common spadefoot present;
red circles – common spadefoot toad breeding ponds.
The common spadefoot toad is an amphibian that leads
a hidden life and is spotted by people quite rarely. Its
lifestyle is nocturnal and it spends its days burrowed in
the soil. The giant common spadefoot toad tadpoles are a
slightly mo
re familiar sight. Still, little is known about the histori
cal distribution of the species. Its distribution area has
decreased considerably and we can only guess how wide
spread this amphibian could have been in Estonia in the
early 20th century, for example. In order to halt the dete
rioration of the common spadefoot toad, we need to learn
Pelobates fuscus
more about the biology of the species and to improve the
quality of its habitats.
Biology of the common spadefoot toad
The common spadefoot toad is an amphibian with a
hidden lifestyle. It enters water bodies only for breeding,
which takes place in Estonia from late April to midMay.
During the rest of the summer, the toads spend their
days burrowed in the soil and emerge only at nightfall to
search for food.
The common spadefoot toad is a very proficient
burrower, opting to hibernate also in the soil. It prefers
open landscapes and relatively deep (up to 130 cm), richly
vegetated breeding ponds. Its spawn takes the shape of a
thick rope and is deposited among aquatic plants.
One female spawns up to 3,000 eggs. As the common
spadefoot toad breeds underwater, the breeding sounds
are difficult to discern. The tadpoles take 80–100 days to
develop, depending on the environmental conditions, and
reach gigantic dimensions premetamorphosis (usually
10–13 cm, sometimes up to 17 cm).
Common spadefoot toad distribution
and research in Estonia
The common spadefoot toad’s historical distribution
area has been limited to mainly the southern and south
eastern parts of Estonia. Due to its extremely hidden
lifestyle, the status of the species has remained unclear
for a long time. The northernmost common spadefoot
localities (in terms of its entire distribution range) have
been found around Porkuni (Aul, 1936). It is known that
in the 1930s, the species was common in some areas
in southern Estonia and that common spadefoot toads
often bred in flax retting ponds (Sibul, 1934). However,
no systematic research on the species’ distribution area
was conducted in the 20th century and we are therefore
left with largely random data. We could thus could con
clude by the end of the century that the common spade
foot toad was a rare amphibian in Estonia. Although its
exact distribution was unknown, it could still be stated
with certainty that its numbers had decreased. In 2007,
we knew of only 80 common spadefoot toad localities.
Since then, the methodology for locating the species has
improved, we have conducted several systematic inven
tories and studied the species’ potential localities by
counties, and extensive management efforts have been
Sausage‑like spawn of the common spadefoot toad
Giant tadpole of the common spadefoot toad
14
launched; as a result, the number of known localities
has increased considerably by 2015 (see Figure 1). We
are now mapping common spadefoot toad distribution
by systematically studying its breeding ponds, with
dipnetting of larvae as the main research method. In
addition to helping us discover localities of the species,
this method allows us to assess the viability of common
spadefoot toad populations and the quality of breeding
ponds as well as the need for and efficiency of manage
ment measures.
The common spadefoot toad currently inhabits areas
with sandy and sandyclay soil in southern, southeastern
and eastern Estonia as well as in Pandivere Heights. The
localities around Porkuni also constitute the north
ernmost border of the species’ entire distribution area
(De Vries et al, 2007).
Habitat requirements of
the common spadefoot toad
The common spadefoot toad is characterised by complex
habitat requirements. It needs both a highquality aquatic
habitat and suitable terrestrial habitats. In Estonia, the
common spadefoot toad mainly breeds in manmade
ponds, beaver floods and smaller lakes. It avoids water
bodies that are large and populated by fish.
An ideal common spadefoot breeding pond is free
of fish and has an extensive shallow littoral zone, where
water heats up fast. The speed of amphibian tadpole devel
opment depends on the water temperature, and common
spadefoot tadpoles metamorphose quicker in warm water.
A shallow littoral zone also provides ample possibilities
for depositing spawn strings. The tadpoles can feed there
and hide from enemies. The common spadefoot toad
has similar breeding pond preferences, for example, in
Sweden (Nyström et al., 2002; 2007). Another important
requirement is that common spadefoot toad breeding
ponds should have good water quality and clayey bottom
sediment.
The same breeding pond characteristics should be
taken into account when restoring common spadefoot
toad breeding ponds. The ponds should have gentle slopes
and be kept free of fish.
It is equally important to have several different
breeding ponds in one habitat. For example, in drought
years the shallow ponds may dry up very fast, causing the
tadpoles to perish. Droughts lasting for several years may
bring about a decline in common spadefoot toad popula
tion numbers.
The common spadefoot toad prefers the ponds to be
surrounded with open landscape with suitable soil for
burrowing. The ideal terrestrial habitat for this amphib
ian are small fields and vegetable gardens, while open
expanses with sandy soil as well as sand and gravel pits
are also suitable.
Threats to the species
The main threats to the common spadefoot toad are
linked to the disappearance of the species’ habitats.
Southern Estonian landscape used to be replete with
ponds and natural depressions that the common spa
defoot toad used for breeding. The small water bodies
were surrounded with fields, meadows and pastures. This
created numerous adjoined habitat clusters, allowing the
common spadefoot toad to move freely between them.
Many of the former habitats have disappeared by
now: the natural depressions and farm ponds have been
destroyed by land improvement, grown over, become
populated with fish and filled in with soil or trash. Open
landscapes have been invaded by scrub or afforested. The
species is also threatened by the intensification of agricul
ture, emergence of massive fields and extensive use of pesti
cides and artificial fertilizers. The negative effect of invasive
alien aquatic species should not be dismissed either.
Because of the trends described above, the distances
between breeding ponds and suitable terrestrial habitats
Eutrophicated pond
Pelobates fuscus
a muddy and overgrown pond being pumped dry for cleaning
have become too great over time and common spadefoot
toad populations are threatened by isolation, which brings
about the depletion of genetic material and the gradual
deterioration of the species.
common spadefoot toad conservation
status and management
The common spadefoot toad is threatened in many Euro
pean countries and populations have been observed to
disappear in much of the distribution area (Eggert, 2002;
Nyström et al., 2002; 2007). Consequently, the species is
listed in Annex IV of the EU Habitats Directive. Accord
ing to the Estonian Nature Conservation Act, the com
mon spadefoot toad is a Category II protected species.
The official basis for managing the conservation of the
common spadefoot toad is the national conservation action
plan for the species. The action plan, compiled as part of
the DRAGONLIFE project, was completed in 2014.
The main aim of the conservation measures for
the common spadefoot toad is to preserve the existing
populations, ensure their viability and expand their dis
tribution area. To this end, we are restoring and creating
breeding ponds suitable for the common spadefoot toad
and managing the adjacent terrestrial habitats.
Both of the conservation measures mentioned above
have also been an important part of the DRAGONLIFE
project. Thus, the project has restored 87 small water bod
ies that are suitable for breeding for primarily the com
mon spadefoot toad and rare dragonfly species. When
selecting the appropriate areas for restoration, we coop
erated with local landowners and informed them of the
habitat requirements of the common spadefoot toad. This
kind of informationsharing is an essential prerequisite for
a successful longterm species conservation project.
References
Aul, Juhan. 1931. Kodumaa neljajalgsed.
Sibul, L. 1934. Uusi andmeid mudakonna kohta Kagu-Eestis.
De Vries et al., 2007. Pelobates fuscus in Estonia. Inventory and suggestions for management.
62 pp. NGO Põhjakonn
Eggert, C. 2002. Decline of the Spadefoot toad (Pelobates fuscus): from population biology to
genetic structure. Bulletin de la Societe Zoologique de France 127(3):273–279
Nyström, P., L. Birkedal, C. Dahlberg and C. Brönmark, 2002. The declining spadefoot toad
Pelobates fuscus: calling site choice and conservation. Ecography 25: 488–498.
Nyström, P., J. Hansson, J. Månsson, M. Sundstedt, C. Reslow and Broström, A. 2007. A
documented amphibian decline over 40 years: Possible causes and implications for species
recovery. Biological Conservation 138: 399–411.
16
Cage for tadpole rearing
The common spadefoot
toad in Denmark
Lars Briggs, Lars Chr Adrados, Niels Damm,
Per Klit Christensen and Kåre Fog
T
he spadefoot toad (or garlic toad) Pelobates fuscus
is often difficult to find, and many populations
may have potentially gone unrecorded. Howev
er, in the recent monitoring program NOVANA
organised by the state, some investigation squares were
selected randomly, and suitable ponds were investigated
there. Populations were rarely found in those ponds. Only
in one or two cases have entirely unknown populations
been found, and only in a few cases have garlic toads been
recorded at distances of a few kilometres from the nearest
known occurrences. This indicates that most but not all
populations in the country have been found and recorded.
The situation of the spadefoot toad is
very different in east and west Denmark
In east Denmark, it occurs on Sjælland and some of the
islands south of Sjælland; but it is rare and has declined
severely. It is extinct in most parts of the region. The larg
est populations in east Denmark are in north Sjælland.
Systematic monitoring started there in 1983, and by 1988
it had become clear that active management of ponds was
crucial for the preservation of the species.
In the former Frederiksborg County, spadefoot toads
were recorded between 1983 and 2005 at least once in 64
ponds. Thirty-three ponds have been improved, either by
Newly metamorphosed toadlet of
the common spadefoot toad
supplemented with intensive efforts of artificial breeding.
However, there is a single case in north Sjælland where
an isolated small relict population of spadefoot toads was
saved. The population was recorded in low numbers in
two or three ponds, none of which were optimal for the
species. One pond was dredged in 2010. It was fenced in
2011 to capture any toads migrating to the pond, but only
Pelobates fuscus
digging a new pond, dredging or excavating, or man
agement by removing willow scrub, etc. In unmanaged
ponds, the average numbers of toads were much smaller
by the end of the study period than at the beginning. The
average number had increased somewhat in managed
ponds with stable toad occurrence, and also increased in
managed ponds with only sporadic occurrence. Alto
gether, out of 64 ponds, the species had survived in 21.
However, the trend was positive in only13 ponds.
After 2005, renewed efforts have been made to
increase the number of suitable ponds in the area, par
tially financed by an EU LIFE project DRAGONLIFE.
By 2015, about 50 ponds have been dug or improved, and
ponds have been managed repeatedly. As a result, the
overall negative trend seems to have stopped now, and
there are some cases where populations have expanded
and colonised new ponds. Nevertheless, in the rest of
Sjælland, the situation is much worse. The spadefoot toads
have mostly been found in only single, isolated ponds,
and nearly all efforts to save such populations have failed.
The populations are probably too inbred to survive, and/
or the efforts to improve the ponds should have been
18
Building a fence to catch breeding toads for captive rearing
two males were caught. In another temporary desiccating
wet depression in the middle of a field, 0.5 km away from
the first pond, a few males were heard, and a part of an
egg string (100 eggs) was found. The eggs were reared, and
the offspring (95) released into the dredged pond. Two
years later, eight males were calling and the population
seems to be saved for now but more supportive breeding
and some habitat management, as well as a monitoring
programme are needed.
On the island of Lolland, spadefoot toads were
recorded in several ponds in 1982. In 1992, only one male
could be heard in one single isolated pond, which had
however been partially filled up and was too shallow. It
was made slightly deeper already in the same autumn,
and a small population of toads managed to survive and
increase in number until 2004, after which it disappeared
quickly. Inbreeding may have played a role. However, a
new large meta-population was discovered in 2006 else
where on the island. The species was recorded in 11 ponds
there, with large populations in some of them. Five new
ponds have recently been made to increase connectivity
between the ponds.
In west Denmark, the spadefoot toad used to be wide
ly distributed in Jutland and on a few adjoining islands.
It has gone extinct in most regions dominated by clay
soils, but has survived in many smaller or larger groups
of ponds on sandier soils. In east Jutland, it has survived
relatively well on the largest peninsula, Djursland. Here,
a large pond project was started around 1990. Aarhus
County announced that people could apply for having
ponds dug or dredged with financial support, so that
the county paid 25–50 % of the costs. At least 400 ponds
were made in this way, and of these, about 20 new ponds
were placed where they would benefit spadefoot toads.
By 2001, four of the 20 ponds had been colonised by the
species. However, several ponds situated less than 200 m
from the existing breeding ponds had not been colonised.
The overall trend for the spadefoot toad on Djursland is
declining. The ponds occupied by the toads in 1990/91
had declined 54 % by 2001. These data illustrate that
creating many ponds over large areas for the benefit of
general biodiversity achieves very little for specific threat
ened populations of rare species.
In 2005, amphibian specialists were contacted with
regard to a large golf course construction near the spa
defoot toad core area on Djursland. At the beginning,
there were about 20 ponds in the area, and garlic toads
occurred in 8–12 of them. Much care was taken to protect
the existing localities, e.g. by creating buffer zones. About
20 new ponds were also created. The results were posi
tive. In 2015, ponds with spadefoot toads had increased in
number from c. 10 to 17, a 70% increase. The great crested
newt Triturus cristatus and the moor frog Rana arvalis also
increased in numbers, to 30 or 31 ponds in total.
Further south in Jutland, initiatives for the spadefoot
toad began in Vejle County in 1996. Since 2000, some
ponds were created as part of an EU LIFE project for the
great crested newt, and a cluster of 12 ponds on state land
with dry grassland and heathlands was evaluated for the
Newly metamorphosed toadlet of the common spadefoot toad
Pelobates fuscus
Release of the tadpoles
reintroduction of the spadefoot toad. The reintroduction
was launched in the framework of the DRAGONLIFE
project (2010–2015). Thousands of reared toads were
released from a nearby population over three years. Two
years after the last release, a total of 35 males were record
ed in nine ponds, but no tadpoles could be found. The
populations of the spadefoot toad have been established
but evaluating successful reintroduction needs further
monitoring. If the population will become successfully
established, it will be recommended to continue with
reintroduction to secure threatened populations not only
where they are today but also in highquality habitats (e.g.
dry grasslands) nearby. Seven or eight ponds had been
created after 2000 in a hilly, moraine landscape for Triturus cristatus. These ponds were then utilised in 2011–2012
to create a reserve population of spadefoot toads. Eggs
were collected and reared from three populations in the
region, and released in the new site. The results were
excellent. In 2014, garlic toads were calling in all seven
ponds where none had live before.
Several attempts have been made to save 13 mutually
isolated populations of spadefoot toads in the former Vejle
County. A total of 67 new ponds have been dug, and 18
old ponds have been dredged specifically for this species.
Out of the 13 populations, 3 to 5 have gone extinct in spite
of the effort. This may be because of immigration of fish
or inbreeding. Five populations have been rescued just in
time by dredging their last breeding pond. The remaining
three populations would probably have survived in any
case, but have now been consolidated and have spread to
neighbouring new ponds. New ponds have been colonised
only in the two largest and least threatened populations.
In the small, barely surviving populations, none of the
newly dug ponds have been colonised up to now.
The largest populations of spadefoot toads in Den
mark were found in the extreme southwest of Jutland,
at Hjerpsted, in 1992. Here, calling males were heard
in more than half, and tadpoles were found in 28 % of
76 ponds investigated in the core area. The populations
were in a severe decline, with tadpoles in only 17 % of
the ponds in 1996. Then, a large pond project was car
ried out from 1996 to 2000; 146 ponds were dredged and
20
Searching for calling males of the common spadefoot toad
36 new ponds were dug here and in neighbouring areas.
The toads responded positively, and at the next census
in 2000, the trend had been reversed. By then, tadpoles
were found in 31 % of the investigated ponds, including
some of the new ponds. All this had been financed by
the county. The county was abolished in the administra
tive reform of 2007 and all efforts there have ceased since
then. As a result, the ponds have deteriorated again and
the populations are back in decline. Most of the ponds are
small and situated in cultivated fields, with few terrestrial
habitats outside of the fields, and the modern scaling-up
of agriculture (larger fields, larger machines) has contrib
uted to the decline.
A more lasting success has been achieved in the
southeastern part of south Jutland, where a new motor
way has been built. As spadefoot toads occurred in the
area, money was provided for replacement ponds. This
gave a big boost to the species, which now has stable
populations in more than 10 ponds there, due to not only
the ponds themselves, but also appropriate improvements
of nearby terrestrial habitats, such as raising the water
level of moors.
For many years, no populations were known in westcentral Jutland (the former Ringkøbing County). Howev
er, two populations of the species were found here around
2000, and these have been supported by pond projects
from 2001 onwards. This has led to the expansion of the
populations and colonisation of new ponds, but also some
backlashes, e.g. due to the release of fish into some ponds.
In the northern parts of Jutland (the former counties
Viborg and Nordjylland), the spadefoot toad has been very
widespread in some regions, but strongly declining like
everywhere else. Up to 1996, only 10 ponds were made for
the species there, and a few of these have actually become
colonised. In recent years, less than 10 additional ponds
have been made. At least 3 have been colonised.
In the region around Viborg, garlic toads were
recorded in many ponds up to 1992. No measures to
preserve the species have been taken there. Of the ponds
where the species was in 1992, 63 were investigated again
in 2009. The species had disappeared from about 75 % of
the ponds (in just 17 years). The main cause of the decline
was the release of fish into many of the larger ponds. But
still, nothing is done for the species in this region.
There are some interesting cases in the northernmost
part of Jutland (Vendsyssel). One case is a pond on a
property with organic farming and with emphasis on the
cultivation of onions. This pond has probably the larg
est population anywhere in Denmark (about 300 calling
males), so it is possible to have large populations if the
surroundings are optimal (onion cultivation is known to
favour the species also in Estonia). It is an isolated popu
lation, but the prospects are good due to organic farming,
which is expected to expand, with the creation of several
additional ponds.
A small surviving spadefoot toad population is found
in a dune area in NW Vendsyssel, 1–2 km from the coast.
In 2013–15, all the remaining adult toads were used in a
breeding effort onsite: the eggs were collected and reared,
and the offspring were released back to the original site
plus into a new site. The success of the project cannot be
evaluated yet, but we know that without egg collecting and
rearing, the original population would have become extinct
in 2015, as none of the original mature specimens returned
to the pond, only the newly released young specimens
returned. There is still hope for this population thanks to a
huge effort made by the DRAGONLIFE project.
To sum up the situation for Jutland, there are very
mixed trends. Where pond projects were financed by the
counties, the initial positive effects have been lost again,
especially when the ponds are among fields and there are
no good terrestrial habitats. On the other hand, where the
projects have been monitored closely by herpetologists
and where there have also been opportunities to create or
preserve good terrestrial habitats, there have been signifi
cant and probably more lasting successes.
Pelobates fuscus
Habitat requirements
of the common
spadefoot toad
Onion beds, typical of Piirissaar Island and the coast
of Lake Peipus in Estonia, are an excellent digging and
foraging ground for the common spadefoot toad
Riinu Rannap, Tanel Kaart, Wouter de Vries,
Lars Briggs, Lars L. Iversen
P
elobates fuscus is a widely distributed amphibian
species in Europe, having an overall decreasing
population trend with particularly dramatic
declines within its northern distribution range
(Fog, 1997; Nyström et al., 2002; 2007), including the
range edge in Estonia and in Denmark (Briggs et al.,
2008). Due to its low abundance and its fossorial and
secretive way of life, little is still known about the species,
especially the use of different habitats and the key habitat
requirements across its distribution range (Eggert, 2002;
Nyström et al., 2007).
Materials and methods
In order to explore the habitat characteristics essential for
P. fuscus, both aquatic and terrestrial habitat features were
included in the study. The fieldwork was carried out in
June 2010 in Estonian and Danish project sites (all Natura
2000 sites), where all small freshwater bodies (e.g. beaver
floods, natural depressions, small temporary lakes, mean
ders and man-made ponds) were examined. Man-made
ponds represented, in our study sites, ponds that had been
created by local people for use as fish, sauna, cattle or
garden watering ponds. In addition, a similar inventory
was carried out in the Netherlands, where P. fuscus is in
decline as well, in order to find out the similarities and dif
ferences of the species’ habitat demands along its north
ern range edge. Given the low abundance of the species
in the Netherlands, we focused on sites (in protected and
unprotected areas) where calling males of the species had
been recorded at least once since 2000. Aquatic and ter
restrial habitat restoration (e.g. removal of mud, creation
of ecological crop and vegetable fields) had been put into
22
practice in most of the Dutch study sites, while in Den
mark, some pond management, influencing ca 10 % of the
water bodies studied, had been carried out over the last
20 years. In Estonia, amphibian-targeted habitat manage
ment had not been implemented in the study sites.
Altogether, 407 water bodies and their surroundings
were analysed for P. fuscus, including 170 water bodies in
Estonia, 191 in Denmark and 46 in the Netherlands. As
adult toads spend most of their terrestrial life in the vicin
ity of the breeding pond and rarely disperse more than
500 m from it (Nöllert, 1990; Hels, 2002), this distance
was taken as a reference point for studying the landscape
characteristics vital for the toad. To detect the species, we
dip‑netted water bodies for larvae. One trained herpetolo
gist visited each water body once and dip‑netted for half
an hour. The same method also provided data on larval
abundance (total number of larvae) and on other amphib
ian species breeding in the same water body. Given the
difficulties in distinguishing the tadpoles of the pool frog
(Pelophylax lessonae) and the edible frog (P. kl. esculentus),
we treated the species in question collectively as “green
frogs” (P. lessonae / esculentus). Additionally, we registered
invertebrate species abundance by making ten dip‑net
sweeps, covering different microhabitats in each pond.
We pre-defined 14 invertebrate groups to be registered
(Turbellaria, Hirudinea, Ephemeroptera, Zygoptera, Heteroptera, Trichoptera, Coleoptera, Megaloptera, Chironomidae,
Gastropoda, Bivalvia, Gammarus, Asellus, Argyroneta). The
presence of fish was established using a combination of
dip‑netting, visual observation and information from
local people. We measured altogether 24 habitat charac
teristics and studied their effects on P. fuscus larvae using
canonical discriminant, logistic regression and Spearman
correlation analysis.
Results and discussion
P. fuscus was found breeding in 11.2 % of Estonian, 11.5 %
of Danish and 28.3 % of Dutch water bodies (Fig. 1). The
higher occurrence rate of the species in the Netherlands
probably derives from differences in our pond selection
process (see materials and methods) and in fact shows
that in 2010 larvae were not found in 71.7 % of the water
bodies which had had calling males at least once in the
past ten years.
Aquatic habitat characteristics
The origins of the water bodies used for breeding differed
considerably between the countries. Although man-made
ponds formed the majority (nearly 60 %) of all breed
ing waters used by P. fuscus in three study countries, the
species still preferred natural water bodies for breeding.
In Estonia, the larvae of P. fuscus were found significantly
more often in beaver floods (30.8 %) than in any other
type of water body (Fig. 2; 3). In the Netherlands, the lar
vae of P. fuscus were mostly found in small (shallow) lakes
(60 % of which had larvae) and in Denmark, in natural
depressions (15.5 % of which had larvae; Fig. 2; 4; 5).
Base-rich sediment (with clayish sediment favoured)
and large areas of shallow littoral zone (water depth ≤ 30
cm) in the water body affected larval occurrence posi
tively. The absence of fish in the breeding ponds was
essential in Estonia and Denmark, but not necessarily
in the Netherlands, where 15 % of breeding sites (N = 2)
had fish. Water conductivity (measured in Estonia and
Denmark) had a significantly positive effect (with lower
11,5%
11,2%
150
With larvae
Without larvae
88,5%
88,8%
100
50
28,3%
71,7%
0
DK
EST
NL
Figure 2.
Proportion of ponds with and without P. fuscus larvae,
depending on pond type and country (the numbers
denote the percentage of ponds without P. fuscus larvae)
(Strijbosch, 1979; Nyström et al., 2002; Rannap et al.,
2013). Shallow littoral zones offer rapidly warming water
and a diverse macrophyte cover, which ensure suit
able egg‑laying sites for adults and foraging and refuge
sites for larvae, resulting in faster development rates
(Semlitsch, 2002; Porej and Hetherington, 2005). The
occurrence of such large and shallow zones could also
explain the observed co-occurrence of fish and P. fuscus
With larvae
Without larvae
100%
60%
84,5%
80,0%
97,7%
100%
40,0%
69,2%
DK
NL
EST
DK
NL
EST
DK
NL
EST
Man made
Natural depression
Lake
85,7%
87,0%
EST
0%
100%
72,4%
20%
90,2%
40%
87,4%
Percentage of ponds
80%
X
DK
X
NL
Beaver flooding
Figure 1. Number and percentage of studied water bodies according to the occurrence of P. fuscus larvae
EST
X
DK
Meander
NL
Pelobates fuscus
200
number of ponds
conductivity favoured) on larval abundance in Denmark.
Shade on the breeding site had a positive effect on larval
abundance only in the Netherlands (Fig. 6). Importantly,
some of these key characteristics differed remarkably
between types of water bodies. For instance, the area of
shallow water was largest in lakes and beaver floods and
smallest in man-made ponds. The latter also had the high
est electrical conductivity and the steepest slopes, while
natural depressions had the shallowest slopes.
Our study revealed that habitat characteristics essen
tial for the breeding site selection of P. fuscus were largely
similar in all study countries. Although man-made ponds
formed the majority of the examined water bodies in all
three range states, larvae were mainly found in natural
waters with clayish sediment and large shallow littoral
zones, indicating that pond quality may be more impor
tant for reproduction than pond availability (Denoël and
Ficetola, 2008). Man-made ponds had generally steeper
slopes and a smaller area of shallow water than natural
water bodies. However, when ponds are specifically con
structed for amphibians in accordance with their habitat
demands, they can successfully function as reproduction
sites and substitute natural water bodies, lacking in mod
ern landscapes (Rannap et al., 2009).
Clayish sediment assures clear transparent water –
an indicator of high oxygen and low nutrient levels
(Brönmark and Hansson, 2005), both vital for the species
24
Figure 3. Beaver flood – a favourite breeding site for P. fuscus in
Estonia
Figure 4. Shallow temporary lake, a breeding site of P. fuscus in
the Netherlands
larvae in two of the Dutch breeding sites: although fish
are considered a major limiting factor for pond-breeding
amphibians (e.g. Hartel et al., 2007), such a coexistence
may succeed in breeding sites with extensive shallow lit
toral zones.
Shade on breeding sites had a positive effect on larval
abundance in the Netherlands. Breeding sites with shad
Figure 5. In Denmark, natural depressions were the favoured
breeding sites for P. fuscus
ing can still be optimal habitats for amphibians at lower
latitudes, where the growing season is considerably longer
(Oldham et al., 2000). Water conductivity – an aquatic
habitat feature that affected larval abundance of the
toad in Denmark (with lower conductivity favoured) – is
related to water quality. High conductivity may indicate
fertilizer pollution (Olías et al., 2008), which poses a seri
ous threat to pond breeding amphibians (e.g. Oldham et
al., 1993; 1997; Davidson et al., 2002). The significance of
this habitat feature in Denmark and not in Estonia may
refer to generally better water quality in Estonian sites.
In Estonia, only 20 % of land is utilised for agricultural
practices and large wilderness areas are still present
(Peterson and Aunap, 1998; Statistics Estonia, 2014). Thus,
the low quality of breeding sites could probably be one of
the limiting factors of Danish P. fuscus populations. Breed
ing site management and restoration should therefore be a
priority and taken as an essential go‑to conservation tool
to save the species in Denmark.
Terrestrial habitat characteristics
The presence of P. fuscus larvae was affected positively
by open biotopes and negatively by deciduous forests in
the vicinity of water bodies in all three countries. How
ever, the type of open biotope in the surroundings of the
breeding site differed between the countries. In the Neth
Pelobates fuscus
0.4
NL
0.2
0
-0.2
Spearman correlation coefficients
-0.4
0.4
DK
0.2
0
-0.2
-0.4
0.4
EST
0.2
0
-0.2
Natural depression
Lake
Man made
Beaver flooding
Meander
Lenght
Width
Area
Shallow area
Max depth
Mean buffer
Average slope
Shadow
Peat
Mud
Clay
Sand
Brown
Clear
Muddy
Algae-green
pH
Conductivity
< 100 m
100–200 m
200–800 m
Nearest forest
Nearest poss. dig. place
Conif. forest
Dec. forest
Bogs/swamps
Crop field
Vegetable garden/field
Gravel pit
Meadow/fen
Grassland (intensive)
Grassland (extensive)
Veget. > 1 m
Veget. < 1 m
Floating veget.
Submerged veget.
Beaver
Fish
Amphibians
Dragonflyes/beetles
Invertebrates
-0.4
Pond type
Pond characteristics
Sediment
Water
erlands, extensively used crop fields, vegetable gardens/
fields and gravel/sand pits had a positive effect on larval
presence, while large areas of uncultivated land (buffer
zone) had a negative effect (Fig. 6). In Estonia, the occur
rence of deciduous forest in the vicinity of breeding sites
had a negative effect on larval abundance, while mead
ows/fens had a positive effect. In Denmark, terrestrial
habitat types did not have any effect on larval abundance
(Fig. 6). Additionally, the number of water bodies near a
Nr ponds Dist.
Habit. 50 m (0/1)
Vegetation
Diversity
Figure 6. spearman rank correlations between larval abundance of P. fuscus and pond and surrounding landscape
characteristics by country
(EST – Estonia, DK – Denmark, NL – the Netherlands); stars denote the statistically significant (p < 0.05) relationships and “×” marks the characteristics
not observed or not variable in the corresponding country.
breeding site had a positive impact on larval presence in
Estonia (Fig. 6).
Deciduous forests in the surroundings of water
bodies tended to have a negative linkage to larvae in
26
all three countries, although the effect was statistically
significant only in Estonia (Fig. 6). This type of forest is
often comprised of large amounts of dense undergrowth
– vegetation the toad is known to avoid (Eggert, 2002).
The particularly negative impact of deciduous forests
in Estonia probably results from open landscapes over
growing due to land abandonment, followed by natural
succession (Peterson and Aunap, 1998) and reforesta
tion (Soo et al., 2009) – a trend much more significant in
Estonia than in Denmark or the Netherlands. The toad
avoiding such densely vegetated biotopes may also explain
why large buffer zones (uncultivated land) around breed
ing sites had a negative effect on larval abundance in the
Netherlands, where uncultivated areas are often densely
vegetated and covered in brushwood.
Although P. fuscus’ larval abundance responded
generally positively to open land cover in all countries,
distinct biotope preferences differed considerably. Mead
ows and fens near breeding sites had a positive effect on
larval abundance only in Estonia. These extensively used
seminatural grasslands provide open sun-exposed habi
tats to different species and have remained quite natural
(fertilizer‑free) in Estonia, as opposed to the Netherlands
and Denmark, where meadows are regularly treated with
artificial fertilizers (Emanuelsson, 2009).
Crop fields in the surroundings of breeding waters
showed a positive association with larval abundance of
P. fuscus in both Estonia and the Netherlands, but not in
Denmark. However, the positive effect of crop fields in
the two countries may have different causes. In Estonia,
where more than 50 % of total land surface is covered
with forests and overgrowing/reforestation is an acute
problem, a general lack of open sun-exposed habitats
increases the value of crop fields. In the Netherlands,
where agricultural land covers more than 60 % of the
total surface area and most of it is managed intensively
(Oenema et al., 2005), nature conservation authorities are
establishing ecological crop fields and vegetable gardens
in the vicinity of P. fuscus breeding ponds by, thus offering
high quality terrestrial habitat for the toads.
Regarding the availability of water bodies near
breeding sites, a higher number was preferred in Esto
nia. Although a clustered configuration of water bod
ies increases the probability of successful breeding and
secures ecological connectedness and the long-term
survival of metapopulations (Semlitsch, 2002; Petranka
et al., 2007), the fact that this habitat feature is important
solely in Estonia might be related to generally low num
bers of high‑quality breeding sites available. It has been
demonstrated earlier by Rannap et al. (2009) that 78 %
of potential breeding waters available in Estonian land
scapes are unsuitable for amphibian reproduction due to
overgrowing, introduction of fish or silting up.
Biodiversity in the breeding site
General amphibian diversity in water bodies (number of
breeding species) was positively associated with the larval
abundances of P. fuscus in three study countries (Fig. 6).
Thus, water bodies favoured for breeding by P. fuscus were
also the preferred reproduction sites for other amphibians
in the area. Consequently, aquatic habitat management
targeted at P. fuscus could also benefit other amphibian
species.
However, amphibian assemblages present in breed
ing sites along with P. fuscus larvae differed remarkably
between the countries (Fig. 7). In the Netherlands, P.
fuscus larvae occurred in the same water bodies with
Bufo bufo, Pelophylax lessonae/esculentus and Rana temporaria, whereas in Estonia and Denmark, the larvae could
be found together with R. arvalis, Triturus cristatus and
Lissotriton vulgaris (Fig. 7). Such differences in amphib
ian assemblages may refer to dissimilarities in breeding
habitat quality between the countries: B. bufo, P. lessonae/
esculentus and R. temporaria are known as species that
tolerate to a certain extent intensively used agricultural
landscapes (Loman and Lardner, 2006), while R. arvalis, T.
cristatus and L. vulgaris avoid such areas (e.g. Loman and
Lardner, 2006; Skei et al., 2006). The latter species also
require breeding sites with clear transparent water and
relatively low electrical conductivity (Skei et al., 2006),
whereas the former can reproduce in freshwater bodies
with variable habitat conditions (Ildos and Ancona, 1994;
Hartel et al., 2008).
Regarding invertebrate diversity in the studied water
bodies, there seem to be general differences between
the three countries rather than between the breeding
and non-breeding sites per se. The ponds in Estonia have
higher diversities and more invertebrate groups associ
ated with established well‑developed water bodies, while
the diversity in Dutch and Danish water bodies is lower
and dominated by different Hemiptera groups. The place
ment of Danish sites on the second axis (see Fig. 8) could
Pelobates fuscus
1.5
Bb
NL +
Rt
0.6
Rl
0.3
Ra
Tv
Ścores of PC2
Loadings of PC2 (20.2%)
1
0.5
EST EST +
0
0
DK -
DK +
-0.5
NL -
Tc
-0.3
-0.2
(a)
0
0.2
0.4
-1
-0.5
0.5
Loadings of PC1 (22.4%)
demonstrate that the invertebrate fauna is dominated by
more temperature‑tolerant species. Estonian and Dutch
water bodies have a higher proportion of species found
in warmer sun-exposed waters. The overall invertebrate
fauna does not differentiate between sites occupied and
unoccupied by the species, which could be caused by a
lack of coherence between aquatic vegetation and locality
size and the presence of P. fuscus. Aquatic vegetation and
locality size are the two major components that define
macroinvertebrate communities in freshwater habitats
(Brönmark and Hansson, 2005).
Suggestions for habitat management
Aquatic habitat management is important for P. fuscus
in all three countries. Moreover, as the breeding success
of P. fuscus was related to general amphibian diversity in
the breeding sites in the studied countries, water body
management targeted at P. fuscus would also benefit the
reproduction success of other amphibian species.
The water bodies favoured for breeding should have:
• a large water table;
• an extensive zone of shallow water;
• no fish in water body;
• clean, transparent water (low conductivity,
no pollution);
• clayish bottom.
In addition to the breeding habitat, the vicinity of
(b)
0
0.5
1
1.5
Scores of PC1
Figure 7. Principal component analyses of amphibian presence.
(a) Loadings of the first two principal components (PC) which
describe 42.6 % of the overall amphibian variation (Bb – Bufo
bufo, Ra – Rana arvalis, Rl – P. lessonae/esculentus, Rt – R. temporaria, Tc – Triturus cristatus, Tv – Lissotriton vulgaris). (b) Average PC scores (with standard errors) of Estonian (EST), Danish
(DK) and Dutch (NL) water bodies with and without common
spadefoot toad larvae (denoted as “+” and “–“ in figure).
reproduction sites should also be taken into account while
planning habitat management actions.
• Open, sun-exposed habitats with sandy or loose soil
should be available in the surroundings of P. fuscus
breeding sites.
• Shrubby areas, brushwood and/or densely vegetated
biotopes should be avoided near the breeding site.
• Intensively used agricultural fields should be avoided
near breeding sites. The pollution from the intensive
ly used fields and farms will spoil the water quality of
breeding ponds. As a result, reproduction might fail
in about 50 % of water bodies, as demonstrated previ
ously in Denmark (Hansen, 2002).
• Organic farming should be promoted, as well as
maintaining and creating extensively used fields and
small vegetable gardens near P. fuscus breeding sites.
In Estonia, avoiding further encroachment of decidu
ous forest and scrub over open landscapes (fields and
grasslands) would also be vital. It is important to allow
beaver populations to thrive and to let them create new
28
In Denmark, avoiding the eutrophication of breed
ing sites by cleaning water bodies and creating new
ones is already an essential tool for species management
and should continue to be so in the future. Adding new
permanent and temporary ponds with large littoral zones
near all breeding sites, which are often isolated, will redevelop metapopulations in the future. In addition, creat
ing extensively used agricultural areas or pastures around
the ponds would prevent eutrophication and increase the
area of terrestrial habitat available for the toads.
In the Netherlands, both the aquatic and terrestrial
habitats of the species should be maintained by creating
new breeding sites and providing high‑quality terrestrial
habitats (organic fields, vegetable gardens) around them.
In addition, originally shallow temporary and fish‑free
breeding sites should not be deepened, but kept tempo
rary as they are now. The temporary nature of the water
body allows the natural drying process to prevent and
eliminate fish predation (Semlitsch, 2000). Deepening
might result in permanent water bodies with steep banks
and narrow zones of shallow water. It is also difficult to
keep such ponds free of fish.
Table 1 features the essential management actions
(both active and preventive) beneficial for P. fuscus.
aquatic habitats for the toads. In addition, the negative
impact of intensive agriculture expanding to areas with
P. fuscus populations should be avoided in Estonia. The
general negative consequences of intensive farming for
amphibian populations have already been demonstrated
in many countries (e.g. Semlitsch, 2000; Cushman, 2006;
Ficetola and Bernardi, 2004).
Table 1. Active and preventive management actions for P. fuscus
Active management measures
Estonia
Denmark
the Netherlands
Maintain existing breeding sites with active management
very important
very important
very important
Create and restore natural depressions (free of fish, with
clean water) with large shallow margins
very important
very important
very important
Create sun-exposed habitats with loose soil near the breeding ponds
very important
very important
very important
Avoid intensive agricultural practices in the close vicinity
of breeding sites
very important
very important
very important
Avoid planting deciduous forest near breeding sites
and in the foraging areas
important
important
important
Avoid natural succession with scrub and deciduous
bushes and trees
very important
in some sites
in some sites
Let beaver populations thrive and make new ponds
very important
important to
launch in some
areas
Preventive measures
Figure 8. Canonical correspondence analysis
(CA) of invertebrate abundance (occurrence
in 10 dip-nets) in Estonian (EST), Danish (DK)
and Dutch (NL) water bodies with and without common spadefoot toad larvae (denoted
as “+” and “–“ in figure)
Corixidae
Notonecta sp
NL +
Loadings of CA2 (16,3%)
5.0
Zygoptera larvae
Chironomidae larvae
Ilyocoris cimicoides
0.0
DK +
Coleoptera larvae
Tricoptera larvae
DK –
Turbellaria
Epemeroptera larvae
Nepa cinerea Siallis sp. larvae
EST –
EST +
Lymnea sp.
–0.5
Aplexa sp. or Physa sp.
Hirundinea
Argyroneta aquatica
Asellus aquaticus
Gammarus sp.
Planorbis sp.
Sphaeriidae
–1.0
Planoorbarius corneus
–1.0
–0.5
–0.0
0.5
1.0
Loadings of CA1 (17,1%)
References
Briggs, L., Rannap, R., Bibelriether, F. 2008. Conservation of Pelobates fuscus as a result of
breeding site creation. RANA Sonderheft 5: 181–192.
Brönmark, C., Hansson, L.A. 2005. The Biology of Lakes and Ponds. Oxford University Press,
Oxford.
Cushman, S. A., 2006. Effects of habitat loss and fragmentation on amphibians: A review and
prospectus. Biological Conservation 128: 321–340.
Davidson, C., Shaffer, H.B., Jennings, M.R. 2002. Spatial tests of the pesticide drift, habitat
destruction, UV-B, and climate-change hypotheses for California amphibian declines. Conservation Biology 16: 1588–1601.
Denoël, M., Ficetola, G.F. 2008. Conservation of newt guilds in an agricultural landscape of
Belgium: the importance of aquatic and terrestrial habitats. Aquatic Conservation: Marine and
Freshwater Ecosystems 18: 714–728.
Eggert, C. 2002. Use of fluorescent pigments and implantable transmitters to track a fossorial
toad (Pelobates fuscus). Herpetological Journal 12: 69–74.
Emanuelsson, U. 2009. The Rural Landscapes of Europe: How Man has Shaped European Nature.
Stockholm, Sweden: Formas.
Ficetola, G. F. and De Bernardi, D., 2004. Amphibians in a human-dominated landscape: the
community structure is related to habitat features and isolation. Biological Conservation 119:
219–230.
Fog, K. 1997. A survey of the results of pond projects for rare amphibians in Denmark. Memoranda Societatis pro Fauna et Flora Fennica 73: 91–100.
Hansen, B. 2002. Calling site choice and reproduction of the spadefoot toad (Pelobates
fuscus) in 50 ponds in Norddjursland, Denmark (Manuscript).
Hartel ,T., Nemes, S., Demeter, L., Öllerer, K. 2008. Pond and landscape characteristics —
which is more important for common toads (Bufo bufo)? A case study from central Romania.
Applied Herpetology 1: 1–12.
Hartel, T., Nemes, S., Cogălniceanu, D., Öllerer, K., Schweiger, O., Moga, C.-I., Demeter, L.
2007. The effect of fish and aquatic habitat complexity on amphibians. Hydrobiologia, 583,
173–182.
Hels, T. 2002. Population dynamics in a Danish metapopulation of spadefoot toads Pelobates
fuscus. Ecography 25: 303–313.
Ildos, S.A., Ancona, N. 1994. Analysis of amphibian habitat preferences in a farmland area (Po
plain, northern Italy). Amphibia-Reptilia 15: 307–316.
Loman, J., Lardner, B. 2006. Does pond quality limit frogs Rana arvalis and Rana temporaria in
agricultural landscapes? A field experiment. Journal of Applied Ecology 43: 690–700.
Nöllert, A. 1990. Die Knoblauchkröte Pelobates fuscus. Die Neue Brehm Bücherei, Wittenberg
Lutherstadt.
Nöllert, A. 1997. Pelobates fuscus (Laurenti, 1768). Pp.110–111 in: Societas Europaea Herpetologica ed, Atlas of Amphibians and Reptiles in Europe. Museum National d’Histoire Naturelle.
Nyström, P., Birkedal, L., Dahlberg, C., Brönmark, C. 2002. The declining spadefoot toad Pelo-
bates fuscus: calling site choice and conservation. Ecography 25: 488–498.
Nyström, P., Hansson, J., Månsson, J., Sundstedt, M., Reslow, C., Broström, A. 2007. A documented amphibian decline over 40 years: Possible causes and implications for species
recovery. Biological Conservation 138: 399–411.
Oenema, O., van Liebe, L., Schoumans, O. 2005. Effects of lowering nitrogen and phosphorus
surpluses in agriculture on the quality of groundwater and surface water in the Netherlands.
Journal of Hydrology 304: 289–301.
Oldham, R.S., Latham, D.M., Hilton-Brown, D., Brooks, J.G. 1993. The effect of agricultural fertilizers on amphibians. English Nature Contract Report. English Nature, Peterborough.
Oldham, R.S., Latham, D.M., Hilton-Brown, D., Towns, M., Cooke, A.S., Burn, A. 1997. The effect
of ammonium nitrate fertilizer on frog (Rana temporaria) survival. Agriculture, Ecosystems
&.Environment 61: 69–74.
Oldham, R.S., Keeble, J., Swan, M.J.S., Jeffecot, M. 2000. Evaluating the suitability of habitat for
the great crested newt (Triturus cristatus). Herpetological Journal 10: 143–155.
Olías, M., González, F., Cerón, J.C., Bolívar, J.P., González-Labajo, J., García-López, S. 2008. Water
quality and distribution of trace elements in the Doñana aquifer (SW Spain). Environmental
Geology 55: 1555–1568.
Peterson, U., Aunap, R. 1998. Changes in agricultural land use in Estonia in the 1990s detected with multitemporal Landsat MSS imagery. Landscape and Urban Planning 41: 193–201.
Petranka, J.W., Harp, E.M., Holbrook, C.T., Hamel, J.A. 2007. Long-term persistence of amphibian populations in a restored wetland complex. Biological Conservation 138: 371–380.
Porej, D., Hetherington, T.E. 2005. Designing wetlands for amphibians: the importance of
predatory fish and shallow littoral zones in structuring of amphibian communities. Wetlands
Ecology and Management 13: 445–455.
Rannap, R., Lõhmus, A., Briggs, L. 2009. Restoring ponds for amphibians: A success story.
Hydrobiologia 634: 87–95.
Rannap, R., Markus, M., Kaart, T. 2013. Habitat use of the common spadefoot toad (Pelobates
fuscus) in Estonia. Amphibia-Reptilia 34:51–62.
Semlitsch, R.D. 2000. Principles for management of aquatic-breeding amphibians. Journal of
Wildlife Management 64: 615–631.
Semlitsch, R.D. 2002. Critical elements for biologically based recovery plans of aquatic-breeding amphibians. Conservation Biology 16: 619–629.
Skei, J.K., Dolmen, D., Rønning, L., Ringsby, T.H. 2006. Habitat use during the aquatic phase of
the newts Triturus vulgaris (L.) and T. cristatus (Laurenti) in central Norway: proposition for a
conservation and monitoring area. Amphibia-Reptilia 27: 309–324.
Soo, T., Tullus, A., Tullus, H., Roosaluste, E., Vares, A. 2009. Change from agriculture to forestry:
floristic diversity in young fast-growing deciduous plantations on former agricultural land in
Estonia. Annales Botanici Fennici 46: 353–364.
Statistics Estonia 2014. Minifacts about Estonia. Pp 4, Tallinn.
Strijbosch, H. 1979. Habitat selection of amphibians during their aquatic phase. Oikos 33: 363–372.
Pelobates fuscus
NL –
1.0
30
Criteria for the
favourable
conservation status
of the common
spadefoot toad
Riinu Rannap, Wouter de Vries, Lars Briggs
P
elobates fuscus is listed in Annex IV of the EU
Habitats Directive (92/43/EEC). Such a status
demands conservation efforts and an explicit
understanding of the species’ habitat require
ments to achieve a favourable conservation status across
the EU. Determining the criteria for assessing the favour
able conservation status of P. fuscus for Estonia and
Denmark has been one of the targets of the LIFE-Nature
Favourable conservation status
When assessing the favourable conservation status of
P. fuscus, we have taken into account effective popula
tion size, the structure of metapopulations (number of
water bodies and the distance between them) and other
parameters. In the course of the project, we have come
to recognize that there are mainly two types of P. fuscus
population structures present in Estonia and Denmark:
1. Isolated populations that do not have possibilities
for immigration. Each isolated population is dependent
on a single breeding site or a very limited number of sites
within a few hundred metres.
2. Metapopulations formed by several sub‑popula
tions of P. fuscus, which are connected to one another
by migration corridors and water bodies, functioning
as stepping stones for the toads. Thus, individuals can
migrate freely between sub‑populations. Even if each
sub‑population has only a single breeding site, the whole
metapopulation system offers several breeding possibili
ties due to connectivity, and in this way, retains the stabil
ity of the entire population. The criteria for assessing the
favourable conservation status of P. fuscus differ accord
ing to the type of population structure.
Tadpole of the common spadefoot toad
Isolated population
•
•
The population must have regular reproduction suc
cess that provides annually an average several hun
dreds of juveniles. A complex of at least three source
ponds, each ≥ 1,000 m2 and in optimal conditions,
can ensure such numbers of juveniles. Although
populations can use only one breeding site and still
survive during a long period, especially in the case
of large waters with flood zones (> 0.5 ha) that yield
regular breeding success with a high number of
juveniles, several breeding sites are still required to
ensure a favourable conservation status of a species.
Habitat components (breeding sites, terrestrial
foraging area, digging sites for hiding and hiberna
tion sites) must be safeguarded in the area where the
population occurs. The components of the habitat
complex should preferably be situated within a dis
tance of 50–250 m.
Onion beds on Piirissaar Island
Pelobates fuscus
project “Securing Leucorrhinia pectoralis and Pelobates
fuscus in the northern distribution area in Estonia and
Denmark” (LIFE08NAT/EE/000257 DRAGONLIFE).
32
Metapopulation
A metapopulation can live in a landscape with a complex
of aquatic sites. The specimens can easily migrate between
different breeding sites, which allows for the exchange of
individuals. The distance between sub-populations can be
over 2 km in landscapes with larger source ponds (annual
breeding success from 100s to 1,000s of offspring). In the
case of smaller breeding sites, the distance between subpopulations should be within one kilometre.
• Each sub-population must have nearly annual breed
ing success of hundreds to over 1,000 individuals.
In large areas with numerous smaller sites, over 10
breeding sites are required, whereas in areas with
larger breeding waters 2 to 3 reproduction sites with
annual breeding success per sub-population should
be assured.
• Habitat components (breeding sites, terrestrial forag
ing area, digging sites and hibernation sites) must be
safeguarded in the area where the population occurs.
• The distance between two sub-populations with large
breeding success should not be more than 2 km, and
there should be easily permeable migration corridors
and foraging habitats. Thick brushwood, intensively
used agricultural fields, roads with heavy traffic, etc.
should be avoided.
• The toads must be assured migration possibilities
between sub-populations by maintaining sandy roads
and pathways, uncultivated areas in field margins,
fenced-out road verges, gardens, etc.
Habitat requirements of the species
In the case of an isolated population or a metapopulation,
the species has the following habitat requirements for a
favourable conservation status:
• The breeding waters must be large (≥ 1,000 m2), fishfree, with naturally clean water (low conductivity)
and an extensive zone of shallow water (up to 30 cm).
For P. fuscus, the preferred sediment type for a breed
ing pond is clay. Additionally, the breeding sites have
to be sun-exposed (without shade), particularly in
Estonia and to a lesser extent in Denmark.
• The terrestrial habitat has to contain sandy and
loose soil (at least within a 100-m radius around the
breeding pond). Deciduous forest should be avoided
in the close vicinity of the breeding site. The pres
ence of open landscapes with areas without inten
sive agricultural practices around the breeding site
(e.g. ecological or extensively used fields, vegetable
gardens, dunes, gravel/sand pits and paths – habitats
with loose sandy soils where the toads can dig in and
forage around) is important.
· There should be no intensive agriculture in the
close surroundings of the breeding sites. Thus, agricul
tural land should be provided with a buffer zone (unculti
vated land) with a minimum width of 10 m around each
water body to avoid the direct influence of fertilizers and
pesticides. In addition, fertilizer-free areas with loose soil
(sand) should be available within 50 m from the water
body to increase the survival of juveniles and adults dur
ing the breeding period.
Pelobates fuscus
Effects of habitat
management on the
common spadefoot
toad
1
2
Riinu Rannap, Kadri Suislepp
Introduction
The common spadefoot toad (Pelobates fuscus) is a widely
distributed amphibian species in Europe with an overall
decreasing population trend. A particularly dramatic
decline is seen within its northern distribution range
(Fog, 1997; Nyström et al., 2002; 2007) including Esto
nia (Briggs et al., 2008), where the species occurs at the
extreme northern edge of its distribution range.
In the first half of the 20th century, P. fuscus was a
rather numerous species in the southern and eastern parts
of Estonia. During the second half of the century, its popu
lation declined rapidly and distribution area diminished.
The main cause for the decline has been the loss of habitats,
particularly aquatic habitats, due to overgrowing, introduc
tion of exotic fish, silting up and eutrophication. Currently,
small and isolated populations of P. fuscus are found in the
northern, eastern and southern parts of Estonia.
3
4
5
Figure 1. Distribution of P. fuscus in Estonia in 2010.
Blue dots – investigated water bodies without P. fuscus larvae; red dots –
water bodies with larvae: project sites: 1 – Porkuni LP, 2 – Mõdriku-Roela LP,
3 – Emajõe-Suursoo NR, 4 – Piirissaar NR, 5 – Karula NP.
34
Restoration of breeding ponds
Five Natura 2000 sites were selected for the project (Fig.
1), covering the distribution range of P. fuscus in Estonia,
including two northernmost European populations in
Porkuni and Mõdriku-Roela. Although the total num
ber of project sites was larger (eight sites in total), three
of them were situated outside the distribution area of P.
fuscus and were therefore not included in this study.
In the very first year of the project, we conducted
a large-scale inventory in all project sites to detect the
breeding sites of the species. During the pre-restoration
inventory in June 2010, six herpetologists from three
European countries checked 155 natural and man-made
ponds, including natural depressions, beaver ponds, cattle
ponds, garden ponds, sauna ponds and ponds historically
used for flax soaking. Data collection was carefully stand
ardised and simplified: we used standard dip-netting of
larvae (Skei et al., 2006) as the main method for detecting
amphibians, and the absence of a species was only con
cluded after 30 minutes of dip-netting. In each pond, the
dip-net sweeps covered all the important microhabitats
for amphibians. In addition, we also searched for the eggs
of newts and egg clusters of the “green frogs” (the pool
frog and the edible frog).
Based on the results of the pond inventory, the target
species was provided with a total of 87 ponds (either
restored or created anew; with 63 in Karula NP, 10 on
Piirissaar Island, 7 in Emajõe-Suursoo NR, 7 in MõdrikuRoela and Porkuni LR) in the autumns of 2010–2014 (after
the reproductive period of most water organisms). New
ponds were created mainly in the places of old ponds that
had disappeared.
In constructing the ponds,
we followed five main principles:
Restored pond
(1) In order to increase colonisation probabilities and
to preserve the existing populations (Semlitsch, 2000;
Petranka & Holbrook, 2006; Petranka et al., 2007), we
constructed ponds mainly in clusters (3–24 ponds in
each, an average of six ponds in a cluster), with distances
between ponds not exceeding 500 m and with at least one
constructed pond within 200 m of an existing breeding
pond of the target species. In Karula and Mõdriku-Roela,
some water bodies were created also as stepping‑stones
between the pond clusters in order to restore the metap
opulation structure of the species.
Project site
No of breeding ponds
in June 2010
(N = 155)
No of constructed ponds
with larvae in 2014–2015
(N = 87)
Constructed ponds
with tadpoles (%)
Karula NP
12
27
42.90 %
Emajõe-Suursoo NR
1
2
28.60 %
Piirissaar NR
2
7
70.00 %
Mõdriku-Roela and Porkuni LP
3
3
42.90 %
Total
18
39
44.80 %
(2) Land cover within 50 m of any constructed pond was
to consist mainly of a mosaic of (semi)natural grasslands
and/or small extensively used fields or vegetable gardens.
(3) In order to assure different hydroperiods (Semlitsch,
2002; Petranka et al., 2003), to improve the ponds’ quality
for P. fuscus and to fit them into the landscape, we applied
various treatments in each cluster. Notably, we construct
ed ponds of various depths (0.5–1.5 m), sizes (150–
2,300 m2) and widths of shallow littoral zone (1–10 m).
In the case of existing ponds, we: (a) cleaned the ponds
from bushes and high dense vegetation (Typha latifolia);
(b) extracted mud down to the mineral soil (mostly clay)
to assure the quality and transparency of water as well as
to eliminate fish (the ponds were also pumped dry for that
purpose); (c) enlarged very small ponds and levelled the
banks to create shallow littoral zones with warm water.
(4) None of the constructed ponds were allowed a connec
tion to running water (ditch, stream, river) to avoid the
introduction of fish or sedimentation (Semlitsch, 2000;
2002); by necessity, any existing ditches were blocked for
the same reason.
(5) As each pond construction was unique (depending on
the relief, soil, hydrology, presence of drainage system,
surrounding habitats, etc.), experienced experts on
amphibian guided the process in the field.
We used excavators for pond digging. After construc
tion, the ponds filled up with rainwater and allowed
colonisation and succession to take their course. The
post-restoration monitoring took place in 2014–2015.
Each pond was visited once and examined in 30 minutes
using visual counting of adults, dip-netting of larvae and
Tadpoles of the common spadefoot toad
searching for the eggs of newts and Pelophylax lessonae.
We ascertained the breeding of P. fuscus by the presence
of larvae. As the spring and early summer of 2015 were
Pelobates fuscus
Table 1. Number of water bodies with P. fuscus tadpoles in 2010 and in 2014–2015 in project sites.
36
90
80
2010
2014–2015
70
60
50
40
Figure 2. Amphibians in existing
water bodies in 2010 (N = 155,
green bars) and in constructed
ponds in 2014–2015 (N = 87, orange bars, red – target species).
30
20
10
0
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to
tri
l
vu
so
Lis
Tr
us
r
itu
c
s
u
at
t
ris
us
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uf
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u
sf
te
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lo
Pe
r
ra
B
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n
Ra
very cold and dry, and thus not optimal for amphib
ian breeding, we used pond colonisation data from the
previous two years (2014–2015) to evaluate the success of
project actions.
Results
In 2010, P. fuscus bred only in 18 water bodies in project
sites, which forms 11.6 % of all investigated water bod
ies (Table 1; Fig. 2). Importantly, 55.5 % (N = 86) of all
investigated water bodies had fish. After pond construc
tion, the species reproduced in 44.8 % of restored or
created water bodies in project sites (Table 1). The number
of ponds occupied by P. fuscus increased 3.9 times in only
four years (from 2010 until 2014).
In addition to P. fuscus, other amphibian species
also benefited from pond construction (Fig. 2). The only
exception was Bufo bufo, which generally favours larger
and deeper water bodies and can also reproduce success
fully in ponds with fish. The most successful colonisers
were Pelophylax lessonae and Lissotriton vulgaris, found
in 80.5 % and 75.9 % of constructed ponds respectively
(Fig. 2)
Discussion
Based on the results of the pond construction carried
out in five project sites, we can conclude that the aquatic
habitat restoration has been successful for
r
aa
s
li
va
n
Ra
ae
on
x
yla
ph
s
les
lo
Pe
P. fuscus – given the rapid spontaneous colonisation of
the constructed ponds and overall population increase
of the target species as well as the general increase in
local amphibian populations. Previous pond restoration
for amphibians has mainly attempted to improve the
local breeding conditions in general, with common spe
cies having benefited the most (Pechmann et al., 2001;
Stumpel, 2004; Petranka et al., 2007). In terms of threat
ened species, success has often remained low (Pechmann
et al., 2001; Stumpel, 2004), even when they have been
specifically targeted (Nyström et al., 2007; Briggs et al.,
2008). Importantly, the few successful cases of habitat
restoration for declining amphibians have always been
carried out at landscape scale, taking into account the
particular terrestrial and aquatic habitat requirements
of the target species (Denton et al., 1997; Briggs, 1997;
2001; Rannap, et al., 2009).
In our project, the main effort was directed at
aquatic habitats, although terrestrial habitats were also
considered (and these appeared highly relevant for P.
fuscus). Open biotopes in the vicinity of the breeding
sites had a positive impact on P. fuscus’ larval presence
and abundance (Eggert, 2002; Nyström et al., 2007),
while deciduous forests in the surroundings of water
bodies tended to have a negative link to larvae. This
type of forest is often comprised of large amounts of
dense undergrowth – vegetation the toad is known to
Pelobates fuscus
avoid (Eggert, 2002). Therefore, in some project sites
(e.g. Piirissaar, Porkuni), terrestrial habitat restoration
(cutting willow bushes, mowing tall and dense vegeta
tion, etc.) should also be taken into account in future
management.
There were probably four general factors that contrib
uted to the success of the project. First, we restored ponds
in clusters, taking into account the relatively limited
dispersal abilities of the target species (Jehle, 2000; Kupfer
& Kneitz, 2000; Nyström et al., 2002) and the preference
of breeding adults to return to natal ponds (Berven &
Grudzien, 1990). The clustering was apparently an effec
tive way to increase the density and number of breed
ing sites at both local population and landscape level.
Secondly, pond quality was considered to be at least as
important as pond availability (Danoël & Ficetola, 2008)
and, as the pond quality may fluctuate (e.g. depending on
rainfall), a variety of ponds were created in each cluster.
This also allows using natural pond drying to prevent
and eliminate fish predation (Semlitsch, 2000), which was
the third key consideration. In accordance with similar
findings in many amphibian species, our target species
avoids ponds with fish (Nyström et al., 2007; Rannap et
al., 2013). Finally, we suggest that the participation of
experienced experts in the field was essential for achiev
ing good results.
References
Berven, K. A. & T. A. Grudzien, 1990. Dispersal in the wood frog (Rana sylvatica): implications for
genetic population structure. Evolution 44: 2047–2056.
Briggs, L., 1997. Recovery of Bombina bombina in Funen County, Denmark. Memoranda Societatis pro Fauna et Flora Fennica 73: 101–104.
Briggs, L., 2001. Conservation of temporary ponds for amphibians in northern and central Europe.
In Rouen, K. (ed), European temporary ponds: a threatened habitat. Freshwater Forum 17: 63–70.
Briggs, L., R. Rannap & F. Biebelriether, 2008. Conservation of Pelobates fuscus as a result of breeding site creation. In Krone, A. (ed), Die Knoblauchkröte (Pelobates fuscus) Verbreitung, Biologie,
Ökologie und Schutz. RANA 5: 181–192.
Danoël, M. & G. F. Ficetola, 2008. Conservation of newt guilds in an agricultural landscape of
Belgium: the importance of aquatic and terrestrial habitats. Aquatic Conservation: Marine and
Freshwater Ecosystems 18: 714–728.
Denton, J. S., S. P. Hitchings, T. J. C. Beebee & A. Gent, 1997. A recovery program for the natterjack
toad (Bufo calamita) in Britain. Conservation Biology 11: 1329–1338.
Fog, K., 1997. A survey of the results of pond projects for rare amphibians in Denmark. Memoranda Societatis pro Fauna et Flora Fennica 73: 91–100.
Jehle, R., 2000. The terrestrial summer habitat of radio-tracked great crested newts Triturus cristatus and marbled newts Triturus marmoratus. Herpetological Journal 10: 137–142.
Kupfer, A., & S. Kneitz, 2000. Population ecology of the great crested newt in an agricultural landscape: dynamics, pond fidelity and dispersal. Herpetological Journal 10: 165–172.
Nyström, P., L. Birkedal, C. Dahlberg & C. Brönmark, 2002. The declining spadefoot toad Pelobates
fuscus: calling site choice and conservation. Ecography 25: 488–498.
Nyström, P., J. Hansson, J. Månsson, M. Sundstedt, C. Reslow & A. Broström, 2007. A documented
amphibian decline over 40 years: Possible causes and implications for species recovery. Biological
Conservation 138: 399–411.
Pechmann, J. H. K., R. A. Estes, D. E. Scott & J. W Gibbons, 2001. Amphibian colonization and use of
ponds created for trial mitigation of wetland loss. Wetlands 21: 93–111.
Petranka, J. W. & C. T. Holbrook, 2006. Wetland restoration for amphibians: should local sites be
designed to support metapopulations or patchy populations. Restoration Ecology 14: 404–411.
Petranka, J. W., C. A. Kennedy & S. S. Murray, 2003. Response of amphibians to restoration of
southern Appalachian wetlands: a long-term analysis of community dynamics. Wetlands 23:
1030–1042.
Petranka, J. W., E. M. Harp, C. T. Holbrook & J. A. Hamel, 2007. Long-term persistence of amphibian
populations in a restored wetland complex. Biological Conservation 138: 371–380.
Rannap, R., A. Lõhmus & L. Briggs, 2009. Restoring ponds for amphibians: A success story. Hydrobiologia 634: 87–95.
Rannap, R., M. Markus & T. Kaart, 2013. Habitat use of the common spadefoot toad (Pelobates
fuscus) in Estonia. Amphibia-Reptilia 34: 51–62.
Semlitsch R. D., 2000. Principles for management of aquatic-breeding amphibians. Journal of
Wildlife Management 64: 615–631.
Semlitsch, R. D., 2002. Critical elements for biologically based recovery plans of aquatic-breeding
amphibians. Conservation Biology 16: 619–629.
Skei, J. K., D. Dolmen, L. Rønning & T. H. Ringsby, 2006. Habitat use during the aquatic phase of the
newts Triturus vulgaris (L.) and T. cristatus (Laurenti) in central Norway: proposition for a conservation and monitoring area. Amphibia-Reptilia 27: 309–324.
Stumpel, A. H. P., 2004. Reptiles and amphibians as targets for nature management. Alterra
Scientific Contribution 13: 75–94.
38
Preservation of the
common spadefoot
toad in North
Rhine‑Westphalia
Results of LIFE project LIFE 11 NAT/DE/348
P
elobates fuscus has become a scarce amphibian
species in North Rhine‑Westphalia (NRW) and
will face complete extinction if not properly pro
tected. Only a few random populations are still
known and they all show negative trends. As this decrease
has been known for years, the species has been registered
in lists of species at risk of complete extinction. Chmela &
Kronshage (2011) have recorded this development and its
escalating trend over the last 10–15 years.
To counteract the complete extinction of the common
spadefoot toad, the Nature Preservation Station Münster
land (NABU) together with the counties of Warendorf and
Borken and the State Agency for Nature, Environment and
Consumer Protection North Rhine-Westphalia (LANUV)
launched the species protection project “Protection of
spadefoot (Pelobates fuscus) in parts of the Münsterland”.
optimization measures, including rescue breeding with the
aim of resettling the bred amphibians into other areas. The
project spans from 2012 to 2016 and is co‑financed by the
EU financial instrument LIFE+.
The following is a summary of some of the experiences
gained during the project. Further information is avail
able at www.knoblauchkroetenschutz.de .
Project activities
Before the project began, two very small residual common
spadefoot toad populations with individual callers existed
in isolated waters within Warendorf County. Both showed
negative tendencies. In order to sustain and promote these
micro-populations, the project carried out measures to
improve the habitat and thus the overall situation of the
species. At the beginning of the project, we optimized the
spawning grounds and removed a shading coppice, which
had a very positive impact on the quality of spawning
waters. Any improvement of the quality of terrestrial habi
tats and migration corridors was very limited, since both
Pelobates fuscus
Initial Pelobates fuscus breeding pond on intensive agricultural landscape
waters are located within an extensively used agricultural
landscape. The private landowners want to use the arable
land for heavy farming without restrictions.
An important aim of the project is to establish new
common spadefoot toad populations. This occurs in habi
tats that are publicly owned, durably assured and where
it is possible to fully implement the necessary nature
conservation measures in accordance with statutory
provisions. Two grazing areas were selected in the Ems
lea in the county of Warendorf, which are characterized
by sandy soils suitable for digging and are known to have
had evidence of past populations.
The Ems lea grazing area “In den Pöhlen” consisted
of 27 ha of floodplain with sandy subsoil. Large popu
lations of Hyla arborea and Triturus cristatus live in the
existing waters. Throughout the year, the surfaces are
40
Restoration of a pond for Pelobates fuscus
grazed extensively with robust cattle and horses (max 0.6
livestock units per ha). The surfaces offer a diverse mosaic
of various habitat structures. In addition to wet and
humid areas with ponds, flood grass and smaller waters,
a 2‑m‑high lea edge runs through the area, so that very
dry sectors can be found as well. Overall, the area has the
full range of microhabitats necessary for the common
spadefoot toad.
As part of the LIFE+ project, we created three new
water bodies and optimized two former fishponds, and
a number of other water bodies are present as well. The
former fishponds are rich in nutrients due to detritus
and very suitable as spawning grounds for the common
spadefoot toad. The remaining populations of fish were
captured and relocated to other ponds outside the terri
tory. The newly created and still nutrient-poor ponds will
be used as spawning grounds in the medium run. With a
total of ten very different ponds in terms of depth, nutri
ent content, the presence/absence of fish and vegetation,
the area “In den Pöhlen” is very rich in waters.
In the 2013 and 2014 project years and even preproject, in 2012, 6050 tadpoles and young toads had been
planted in “In den Pöhlen”, which resulted in initial suc
cess in 2015.
In spring, nearly 80 adult and spawning-ready common
spadefoot toads of both sexes wandered to the spawning
grounds in question. A random test led to the discovery of
two spawning cords, from which 270 subadults migrated
Pelobates fuscus
Tadpoles were reared in huge round basins
a few weeks later. There is great hope that the stocks
continue to perform well during the following years and
ultimately spread.
Another extensively used grazing land at the EmsHessel-Lake, which is part of the Natura 2000 area DE
4013-301 “Ems lea, district of Warendorf and Gütersloh”,
was selected as the second area. There, we created two
new water bodies and sand dunes to optimize terrestrial
habitats.
From 2013 to 2015, 3020 tadpoles and young toads
were planted with a calculated first returning migration
in 2016.
In addition, 2140 tadpoles and young toads were also
planted within the district of Borken in western NRW.
The area is known as “Eper-Venn” (Natura 2000 area
DE-3808-301 “Eper Graeser Venn / Lasterfeld”, part of
the bird sanctuary DE-3807-401 “Fens and heaths of the
western Münsterland”). The area, which is run by the
Biological Station Zwillbrock, was formerly inhabited by
the common spadefoot toad. The species died there due to
habitat deterioration. A reintroduction was planned after
major optimization measures. The goal of these new and
reintroduced populations is to generate three independent
and strong populations that can constitute future sources
for further colonization.
Protective breeding
The most important requirements for reintroduction
and new populations are the criteria of the International
Bamboo poles were used for egg laying
Union for Conservation of Nature (IUCN). The catalogue
of the IUCN provides a number of measures and require
ments that are of biological as well as socio‑economic and
legal nature (IUCN 1998, IUCN / SSC 2013).
The main criteria include the clarification of the spe
cies’ habitat requirements, the selection of a suitable and
large exposure area, its long-term protection as well as the
identification and possible elimination of the original fac
tors responsible for the species’ demise. Also important
are the availability of appropriate stocks for the reintro
duction of the species, a long-term commitment and the
monitoring of individuals after their return to the wild.
There are only a few published in‑depth accounts of
rearing common spadefoot toads with the aim of protec
tive breeding. In the project’s early stages, only Klose
42
Fences were built to catch migrating amphibians
All common spadefoots were weighed and measured
(2009) had reported of cases of rearing the species in
Schleswig-Holstein (Northern Germany). As the opera
tions carried out during the project differ in parts from
the described procedure, we should present them here. A
detailed description can be found in Göcking et al (2013).
The project carried out conservation breeding in two
different locations due to related risks.
their spawning cords at an appropriate water tempera
ture > of 15 °C. The adult amphibians were subsequently
removed from the basins and released into nature again.
We did not observe a crowding effect, in which a por
tion of the tadpoles are stunted in their development and
often ultimately die. This may be due to the large volume
of water.
Keeping and rearing
Food supply
The rearing of the tadpoles took place mainly outdoors, in
round basins with a water capacity of approx. 600 litres.
A few weeks earlier, the basins were filled with water from
our own well (no tap water). As a result, water chemistry
could adjust and water temperature heat up appropriately.
The water was filled with water fleas and algae taken from
natural sources. This ensured colonization of the basins’
walls and the further development of algae and animal
microorganisms.
Parallel to filling the basins with water, we installed
5–10 clay pots with inserted bamboo poles. These
bamboo poles simulate the natural vertical vegetation
structures that occur in natural spawning grounds. We
refrained from processing or altering the water or the
basins and from using additional equipment (e.g. UV
filters).
Shortly after the introduction of the spawning-ready
animals, the mating began. The majority of couples laid
The supply of food in various forms was adapted to the
age of the tadpoles. The first food intake happened after a
few days, when the animals fully consumed their yolk sac
and began swimming. At that time, the natural growth
on the basin walls and the inserted rods and pots was
available.
The surface film (neuston) of the basin was grazed
quickly and intensely and it developed numerous algae
and bacteria. It turned out to be a very suitable food
source. Afterwards, we added first external feedings in
the form of algae (not filamentous algae) with a very soft
structure. We also fed the tadpoles leaves of e.g. hazel
bushes soaked in water. The leaves were also colonized by
algae and microorganisms in a few days and could be fed
to the tadpoles. The tadpoles were grazing on the leaves
but very quickly started to eat the leaf mass up to the leaf
veins.
In the next step, we fed the tadpoles, by then 4–5
Pelobates fuscus
weeks old and 4–6 cm long, their main food source,
which consisted of wild herbs. For this, arable herbs were
collected daily at a nearby organic farm.
The animals preferred soft-leaved plants, such as
• goosefoot (Chenopodium sp.);
• Galinsoga sp.;
• Chinese cress (Capsella bursa-pastoris);
• chickweed (Stelleria media);
• lettuce (from organic farming).
With a stock of about 300 animals per basin and
warm temperatures, 10 litres of herbs were fed daily and
were almost completely eaten. Animal protein was sup
plied secondarily, as the collected herbs always contained
small animals (e.g. aphids, spiders). The use of any
biocides in the type of water in question is not feasible or
necessary. Biocides have been proven responsible for the
decrease of amphibians (cf. Brühl et al, 2013).
Common spadefoot toad tadpoles also feed on Daphnia. We witnessed the tadpoles crossing swarms of water
fleas, open-mouthed, to get to Daphnia.
Overall, it has proven helpful to use very large breed
ing basins with correspondingly large water volumes. As
a result, there was no need for an elaborate filtering or
several water changes, which cause much unrest and loss
of material due to the tadpoles swimming around more
actively. We installed a small solar‑powered circulation
pump that we used only on the hottest days to allow the
supply of atmospheric oxygen.
The described, virtually seminatural rearing of com
mon spadefoot toads strengthens the resistance of the
animals and thus promotes successful further develop
ment in nature. Animals that grow up in hygienically
clean basins with only a few bacteria probably have
diminished ability to build the necessary defences. We
do not know of more detailed studies on the survival or
health of artificially reared amphibians.
In order to achieve optimum breeding results, a
600‑litre round water basin did not contain more than
300 tadpoles at maximum body size. The tadpoles were
released into the wild before and after metamorphosis,
i.e. with grown hind limbs and unerupted front legs, but
also as fully metamorphosed animals. In addition, we
also built a 100‑m2 outdoor terrarium to keep the animals
under human care for a longer period.
Monitoring
To document a project’s success, subsequent monitoring
is essential. In our case, this is done using amphibious
fences erected in the direct vicinity of the reintroduction
waters. This made it possible to document the migration
and immigration of spawning-ready animals. Informa
tion on other amphibious species within the waters is
also important for us. To limit the numbers of undetected
aquatic newts, we devised and built a special fence with a
climbing barrier. The fence functioned relatively well due
to its flexible plastic webbing and has since been used in
various other waters.
We inserted buckets into the ground on both sides
of the fence at intervals of several metres, to capture the
migrating and immigrating animals properly. We do not
know to what extent the animals are able to climb over
44
•
we optimized and developed as spawning grounds
two waters with small remnant populations;
• we created new water bodies in two other areas;
• we carried out rescue breeding of the common spade
foot toad, which resulted in reintroducing tadpoles
and young toads into the wild.
The year 2015 yielded the first returning migration of
adult, spawning-ready animals that reproduced successfully.
Acknowledgment
Johannes Kirchner developed and built the amphibious
fences with the climbing barriers. Franz Kraskes and
Michael Bisping developed the tadpole breeding method
and conducted the rescue breedings.
Contact information
NABU-Naturschutzstation
Münsterland e.V.
Haus Heidhorn
Westfalenstraße 490
48165 Münster, Germany
[email protected],
[email protected]
the fence as quantification is naturally impossible
(cf. discussion in Jehle et al, 1997).
In the area of “in den Pöhlen”, we captured 3,921
amphibians of seven different species, and documented
their migration to and from the waters (note that Pelophylax kl. esculentus was not included).
For further studies, we additionally photographed
morphometric data, such as weight and size of the toads
as well as dorsal drawings, enabling us to document indi
vidual development in the coming years. The common
spadefoot toad’s dorsal drawings are as individual as the
human fingerprint.
Summary
In the course of the LIFE+ project (LIFE 11 NAT/DE/348
“Preservation of the spadefoot toad in parts of the Müns
terland”), a number of measures to protect Pelobates fuscus
are carried out between 2012 and 2016, including the
following:
References
BRÜHL, C. A., T. SCHMIDT, S. PIEPER& A. ALSCHER(2013): Terrestrial pesticide exposure of
amphibians: An underestimated cause of global decline? – Scientific Reports 3: 1135, doi:
10.1038/srep01135.
CHMELA, C. & A. KRONSHAGE(2011): 3.8 Knoblauchkröte – Pelobates fuscus. In: HACHTEL, M.,
M. SCHLÜPMANN, K. WEDDELING, B. THIESMEIER, A. GEIGER& C. WILLIGALLA(Red.): Handbuch
der Amphibien und Reptilien Nordrhein-Westfalens. Band 1: 543–582. – Bielefeld (Laurenti).
IUCN (1998). Guidelines for Re-introductions. Prepared by the IUCN/SSC Re-introduction
Specialist Group. – Gland, Switzerland & Cambridge, UK (IUCN).
IUCN/SSC (2013): Guidelines for Reintroductions and Other Conservation Translocations.
Version 1.0. Gland, Switzerland: IUCN Species Survival Commission, viiii + 57 pp.
Göcking, C., M. BISPING, F. KRASKES, N. MENKE, T. MUTZ & C. RÜCKRIEM (2013): Erhaltungszucht der Knoblauchkröte – Haltung und Aufzucht von Laich und Kaulquappen. –
Zeitschrift für Feldherpetologie 20: 171–180.
Jehle, R., N. Ellinger & W. Hödl (1997): Der Endelteich der Wiener Donauinsel und seine Fangzaunanlage für Amphibien: ein sekundäres Gewässer für populations-biologische Studien.
- Stapfia 0051: 85-102
KLOSE, O. (2009): Die Unterstützungsaufzucht als Beitrag zum Schutz der Knoblauchkröte
(Pelobates fuscus) – Erste Erfahrungen aus Schleswig-Holstein. – Rana 10: 30–40.
Pelobates fuscus
A relatively large water body with extensive, sunexposed and shallow embankment zones where a large Pelobates fuscus
population was breeding in 2010. No larvae could be recorded in 2014. Over a few years, the direct surroundings have become
densely overgrown with tall vegetation and the small ecological fields have disappeared. Groot Soerel, the Netherlands.
Status of the common
spadefoot toad in the
Netherlands
Wouter de Vries
T
he decline of the common spadefoot toad
Pelobates fuscus has been documented in the
Netherlands for decades and the species was
listed in the Red Data Book as a threatened spe
cies in 1996 and 2007 (van Delft et al., 2007). The National
Species Conservation Action Plan was published in 2001
(SBPK; Crombaghs & Creemers, 2001). The actions that
were taken under this plan did not stop the decline of this
rare species (van Delft et al., 2007; Bosman et al., 2015).
After the government stopped financing the execution of
the action plan for the species in 2010, the actions were
transferred to the regional level and became the respon
sibility of the provinces. During the DRAGONLIFE
project, two actions were carried out in the Netherlands:
in 2010, research on the habitat demands of Pelobates
fuscus (Rannap et al., 2011 and in press); and in 2014, a
study tour to the regions and sites that had been included
in the research in question. These actions were carried out
under the initiative of the Estonian beneficiary.
Professionals from the Dutch association RAVON
participated in workshops and other actions in Estonia,
the Netherlands and Denmark in a previous LIFE project
(BALTRIT, LIFE04NAT/EE/00070) in 2008 and later
in the DRAGONLIFE project. Captive breeding pro
grammes of common spadefoot toad have been developed
in the Netherlands since 2009, and over 86.371 larvae
46
Table 1. Relative population size of Pelobates fuscus populations in the 46 investigated waters, based on SBPK criteria
and the number of calling males in the period 2000–2010
Population size
(number of calling males)
Number of
sites with
Pelobates
2000–2010
Sites
included in
the research
of 2010
0
8
0
Very small population (1–4)
51
20
Small population (5–10)
22
19
Large population (11–25)
6
5
Very large population (> 25)
3
2
Total
90
46
Table 2. Negative factors as described in the SBPK (Crombaghs
& Creemers, 2001) in the investigated remaining Dutch
“breeding” sites (n = 46) in 2010 and proportion of larvae
detected in 2010
Negative factor (SBPK)
Number of
sites
Sites with
larvae in
2010
24
5
pH < 6
4
0
Fish present (2010)
10
2
Surface < 500 m
2
Unclear water (muddy)
9
0
Aquatic vegetation (< 5 % floating AND < 5 % submerged)
16
6
Hypertrophic
1
0
Considerable shade
6
3
Number of sites with over one
negative factor
35
9
Table 3. Criteria for defining the status of 46 “breeding” sites
(based on SBPK criteria; Crombaghs & Creemers, 2001) and
proportion of investigated sites (n = 46) in each status cate
gory in 2010
Number of
larvae in
2010
Number of
negative
factors present
Percentage
of investigated waters
(n = 46)
Optimal
> 10
0
6.5 %
Marginal
1–10
0
2.2 %
Threatened
> = 1
> = 1
19.6 %
Very threatened
0
> = 1
60.9 %
Status not
defined
0
0
10.9 %
Figure 1. Status of the common spadefoot toad (Pelobates fus-
cus fuscus) within its European distribution range.
Red: recently extinct; orange: threatened; yellow: vulnerable; grey: status
unknown; green: not threatened; white: outside the range (based on
national red data books and expert comments).
or (nearly) metamorphosed toads have been released in
the Dutch countryside (Crombaghs et al., 2015). A large
number of volunteers and professionals are involved in
collecting eggs and breeding larvae. A positive outcome
of all the efforts is that Pelobates fuscus males that had
originated from captive or semi-captive breeding and had
been released were calling in aquatic sites in 2015. These
actions increased the probability of survival for Pelobates
fuscus in the Netherlands because there are juveniles now.
However, the actual causes for the decline have not been
alleviated. The breeding and releasing will have a similar
effect as an aspirin would have on a woodpecker after
it has been hitting a stone wall because it has not been
provided with a tree full of life. Changes in the Dutch
management of Pelobates fuscus populations are urgently
needed to provide the tens of thousands of young adults
with a suitable habitat. The following presents a reflection
on the status of the species and its habitat on the basis
of research done during the DRAGONLIFE project (for
background, methods and results see: Rannap et al., 2011
and in press) and on the basis of 15 years of research on
80
60
40
2013 (%; n=146)
20
2014 (%; n=181)
2015 (%; n=105)
0
a
ta
fo
lis
us
gs
ris
ae
na atus aria
ita ridis
re
bi
r
bu ulen lam
t
fro fusc ulga sson arva rbo
o
vi
s
m
o
i
n
p
o
a
s
v
sc a ca
cr
fo
uf
le ana
w
e
b
m
s
a
e
u
t
B
s
o
l
e
a
a
B
u
ru
n
R
br oba
na Buf
Hy bin
at
ur
itu
Ra
l
Ra
an
rit
Tr
m
T
Pe
R
Bo
gs
ee
gr
ro
nf
Amphibian species
Figure 2. Results of a threeyear EPMAC amphibian monitoring in northeastern Poland. Proportions of sites in which each species was detected during June samplings (www.epmac-europe.com)
this species in optimal or remaining habitats or land
scapes in the northern and western distribution range of
Pelobates fuscus (W. De Vries, 2007 to 2015; Briggs et al.,
2009; Rannap et al., 2011, 2012, 2015 & in press; Kielgast
et al., 2012; Damm et al., 2009; Buro Bakker, 2004; Adra
dos et al., 2002; Janse & De Vries, 2000; Loo & De Vries,
2000).
Research on habitat requirements
and status in the Netherlands
The DRAGONLIFE research, done simultaneously in
Estonia, Denmark and the Netherlands, included 46
known Dutch Pelobates fuscus breeding sites. The meth
ods, backgrounds and results of this study are reflected
in Rannap et al, 2011 and in press. In each of the selected
sites in the Netherlands, calling males or larvae had been
recorded since the year 2000 (see Table 1). Already in
2010, ten of the country’s 29 population areas (referred
to as leefgebieden in the SBPK; Crombaghs & Creemers,
2001) did not have regular reproduction or sites with over
five calling males (data analysed for the study in ques
tion; similar to Bosman et al., 2015). The 46 preselected
sites were divided among 16 of the 19 population areas left
with a small remaining population.
In 2010, larvae were caught in 29 % of the investigated
survey sites. One negative factor or more were present in
35 of the 46 waters with a population (see Table 2). Less
than 10 % of the surveyed sites with a Pelobates fuscus
population had optimal or marginal conditions for suc
cessful breeding (see Tables 2 and 3).
No larvae were recorded in unclear or hypertrophic
waters or waters with a pH below six (slightly acid waters).
Fish were detected in ten sites and Pelobates fuscus larvae
in only two sites, together with small fish. In six popula
tion areas no larvae were caught; two had two breeding
sites and eight just one breeding site with larvae. A short
summarizing conclusion: extremely unsuitable conditions
for successful breeding after over a decade of intensive
habitat restoration and improvements for the species.
Importantly, the DRAGOLIFE research concluded
that in Estonia, Denmark and the Netherlands, the com
mon spadefoot toad bred especially well in (larger) waters
Pelobates fuscus
Detection (percentage of surveyed sites % with
recordings of the species)
Results EPMAC-AMPHIBIAN monitoring
bialowieza/narew northeastern poland
48
with an extensive flood zone without fish (Rannap et al.,
2011 & in press). Other conclusions of the research are
that the species prefers to breed in more natural waters,
with clear water and a rich vegetation structure. The
results of the investigation in the Netherlands showed
that the breeding sites and terrestrial habitat in the
remaining areas with surviving specimens of Pelobates
fuscus were far from optimal for the species in terms of
the habitat criteria as defined in the SBPK (Crombaghs &
Creemers, 2001) and the DRAGONLIFE research (Ran
nap et al., 2011 & in press).
Study tour 2014
The results of the 2010 research were communicated to
the organizations involved in the management of the
species in the Netherlands. During the study tour of
2014, experts visited four areas and surveyed the larvae.
The results were surprisingly negative, even while taking
into account that 2015 was not a very good year for the
reproduction of the species in many regions (De Vries
& Van de Loo, 2015). During the repeat investigation of
2014, larvae were caught only in the last remaining large
population of the species. In the area of the river Vecht,
no larvae were caught, even though the flood zone of old
meanders did have larvae of the fish Misgurnus fossilis
(indicating positive spring flooding conditions). Inten
sive farming with the injection of dung is still ongoing in
and alongside this site. A second area, at the river Waal
(Ewijk), has had road construction and an amphibian
fence installed after 2010. The amphibian fence is located
between a large shallow flooding and the higher sandy
soils of the dike and the bridge. This site used to have one
of the largest Pelobates fuscus populations. Water quality
does not seem to be an issue, as other species requiring
highquality water were present (Hirudo medicinalis and
Triturus cristatus). It would be speculative to state that
this population is on the brink of extinction because of
the construction work or the location of the amphib
ian fence, which could block migration to the terrestrial
habitat. If there had been specific research on the habitat
that the community had actually used before the road
work and mitigation actions were undertaken, the strong
decline might have been avoided. A third area where two
breeding sites were surveyed again in 2014 is close to the
river IJssel in an area with ecological cropseed produc
tion. One of the sites had become fully shaded by trees
in 2014 and small ecological cropfields had overgrown in
the vicinity of the second site. No larvae were recorded
anymore. In the fourth surveyed area near the city of
Nijmegen, no larvae were caught in 2014. One of the
breeding sites in the area had now unclear water. A sec
ond site had clear water, but no larvae had been caught in
2010 either, even though there are breeding adults; finally,
a third site has fish and reproduction success has not been
documented in recent years.
At the same time that we observed the ongoing dete
rioration of the habitat and reduced reproduction success,
nearly 100,000 eggs and larvae were raised and released
within about 200 kilometres from their original site.
The areas in which larvae and juveniles are released are
selected and designed using criteria that are mostly based
on references on the last surviving (now actually dying!)
populations in the Netherlands.
Limitations and future for the populations
in the Netherlands
The limitations for Pelobates fuscus in the Dutch country
side could be due to the disappearance of landscape that
can provide large populations in and around existing sites
with calling males. The few remaining small populations
depend(ed) on one or two sites. The intensification of
agriculture and intensive management of water dynam
ics have caused the more suitable breeding and terrestrial
habitats to disappear. In much, if not all of the range, this
species has very large populations in areas and landscapes
with vast areas of temporary waters. Depending on the
region and climatic conditions, these waters are not even
formed every year or not suitable for breeding every year.
An illustrative example comes from northeastern Poland
and is taken from the EPMAC monitoring (Figures 2 and
3; De Vries & Van de Loo, 2015). This landscape is similar
in structures to the Dutch lowland, featuring agricul
tural areas, forests and river valleys. The most important
difference is that there is a more natural hydrology; the
climate is slightly more continental than in the Nether
lands. Importantly, there is very low to nonexistent input
of chemical pesticides and fertilizers. The results of three
years of the EPMAC amphibian monitoring demonstrate
that Pelobates fuscus is one of the dominating species in
this landscape. In 2013, the species was present in over
40 % of surveyed sites, including in all flood areas of the
Narew River, in inundations in fields and on meadows
Pelobates fuscus
An example of an optimal reproduction site: large, shallow,
sunexposed and without fish, open sandy soils in the immediate surroundings and the site itself located far from intensive
agriculture. There are years without any surface left. Ewijk,
the Netherlands.
and in large flood zones around permanent ponds. In
2014 and 2015, the species was detected in 20 % and 10 %
of surveyed sites respectively. The years in question had
much less surface water due to two years with low pre
cipitation (incl. snowfall). In 2015 and 2014, the landscape
and hydrological conditions were similar to those in all
years in western European landscapes: dry areas with
water left in ponds, lakes, ditches, channels and rivers.
Even in Poland, temporary inundations and extensive
flood zones had no or very little water in the latter two
years and no to few larvae. If we used these landscape
and hydrological conditions as a reference for describing
Pelobates fuscus breeding sites, we would conclude that
Pelobates fuscus is a rare species that lives in ponds. How
ever, in the wet years (as was the case especially in 2013),
the species actually has a much wider range of habitats
and breeds with great success, yielding, on a regular basis,
Pelobates fuscus, once a characteristic species of the Dutch
agricultural landscape with longlasting floods and vast wetlands in wet years, has now become a very rare and threatened species on the brink of extinction. Estonia, 2012.
tens of larvae per catch in temporary inundations. These
inundations dominate the Polish landscape and used to
cover extensive areas in the Netherlands. Where these
inundations surrounded sandy soils, the species found
optimal conditions. This was the case along larger rivers
50
Missing tail tips on larvae from a large breeding population
that lives together with sticklebacks; the coexistence might
be explained by the high population density of Pelobates fuscus and fast growth of larvae. Agnietenberg, the Netherlands.
Dying Pelobates fuscus larvae in 3 cm deep water in dark
mud in a naturally drying lake with a very large population.
While many larvae die in some years, a large number of dying specimens is a sure indication of the presence of a large
population. Estonia, 2007.
(e.g. Maas, Waal, and IJssel), stream valleys (e.g. Dommel,
Hunze, and Reest), marshes (Wieden) and on fertilized
agricultural sandy plains (higher sandy soils). Histori
cally, ponds have not been an important water element
in this landscape in the springtime, when the species
reproduces, but the core breeding areas have actually
been formed by the temporary waters and large flood
zones around beaver floods, lakes and rivers. This can still
be observed in the Estonian (e.g. De Vries, 2007–2014),
Lithuanian (e.g. Van de Loo & De Vries, 2000; De Vries,
2013) and Polish landscapes (e.g. Adrados et al., 2002;
De Vries & Van de Loo, 2015; Janse & De Vries, 2000). In
fact, the remaining large populations over much of the
range have survived in places where such waters are still
or were until recently present (also in Belgium, France,
Denmark; pers. observation).
The last surviving populations in the Dutch areas
where Pelobates fuscus survived until the 1990s, when
conservation measures increased, used larger temporary
waters and permanent waters around those. Fortunately,
nature conservationists have recently realised that con
servation actions have not always provided more suit
able conditions for the species (Bosman et al., 2015). The
surviving populations had been using larger temporary
waters or waters that (nearly) dried in some summers.
As we can see in Poland and Estonia, Pelobates fuscus
tadpoles are often dying in these waters by the hundreds
in the month of June in some years (see photo). Nature
conservationists have reacted to this by deepening the
waters. Consequently, the habitat has become suitable for
another species spectrum and different densities; spe
cies that are more adapted to permanent waters: larger
dragonflies, beetles, Triturus species and fish. Most sites
became populated by fish within ten years and Pelobates
fuscus became (almost) extinct. In other sites on higher
grounds, organic matter was removed, which lowered
buffering capacity and increased acidity (causing the eggs
to die). Even today, naturalists find it difficult to fathom
that Pelobates fuscus is actually not a pondbreeding spe
cies, like newts and green frogs, but a species characteris
tic of temporary waters, including river flood zones.
Returning to the actual status of the species in the
Netherlands, I would like to express my gratitude to all
who have already put so much effort into the conserva
tion of the common spadefoot toad in the Netherlands.
All this input has created a better understanding,
which makes this the perfect moment to shift the spe
cies management strategies towards a living landscape
approach. Earlier this year, Ottburg et al. (2015) published
a reflection on the future management of the species
populations comes from Sweden, where Nystromm (2008)
has recuperated populations in landscapes less influenced
by intensive farming, featuring complexes of breeding
sites. In conclusion, the DRAGONLIFE research on habi
tat requirements included populations from the Neth
erlands, Denmark and Estonia. On the basis of research
results (Rannap et al., in press), the optimal conditions for
breeding sites were defined and used to successfully create
or optimise breeding sites in Denmark and Estonia (this
publication). These positive conclusions and results from
the DRAGONLIFE project can also be implemented in
the Netherlands.
References
Adrados, L. C., L. Briggs, W. de Vries, M. Elmeros & A. B. Madsen (2002). Via Baltica, solutions
to conflicts between amphibians, mammals and roads. Technical report number 9 for
the project Fauna passages under selected roads in Poland; education, monitoring and
construction – part A.
Bosman, W., R. Struijk, M. Zekhuis, F. Ottburg, B. Crombaghs, D. Schut & P. Van Hoof (2015).
De Knoflookpad in Nederland: ondergang of ‘slechts’ een bottleneck? / Pelobates fuscus in
the Netherlands, towards extinction or “just” a bottle-neck? De Levende Natuur. Jrg. 116, nr.
1. Blz. 2–6.
Buro Bakker (W. de Vries) (2004). Onderzoek naar noodzakelijke maatregelen voor het
behoud van de Knoflookpad (Pelobates fuscus) in Drenthe. / Management requirements for
the conservation of Pelobates fuscus in the Province of Drenthe, the Netherlands. + Bijlagenrapport. Publication Buro Bakker.
Briggs, L., W. de Vries & F. Biebelriether (2009). Vorläufige Potenzialanalyse des Natura 2000
Gebietes Strothe/Almstorf (LK Uelzen) für die Rotbauchunke (Bombina bombina). AmphiConsult (2008). In German (Preliminary analyses of the potential for the firebellied toad
(Bombina bombina) in the Natura 2000 areas Strothe/Almstorf (region Uelzen)).
Crombaghs, B. H. J. M. & R. C. M. Creemers (2001). Beschermingsplan Knoflookpad
2001–2005. Species Conservation Plan for Pelobates fuscus in the Netherlands 2001–2005.
Rapport Directie Natuurbeheer nr. 2001/19. Ministerie van Landbouw, Natuurbeheer en
Visserij, Wageningen.
Crombaghs, B., I. van Bebber, J. van der Zee, D. Schut, P. van Hoof, J. Janse, R. Zollinger,
F. G. W. A. Ottburg, M. Zekhuis, J. van der Weele & H. A. H. Jansman. Kweek- en uitzetprogramma van knoflookpaddenlarven. Captive and release programme of Pelobates fuscus in
the Netherlands. De Levende Natuur jr. 116. Nr 1. January 2015. The Netherlands.
Damm, N., W. de Vries & L. Briggs (2009). Pelobates fuscus in Vejle County Denmark, results of
survey 2009. Amphi Consult. Technical Report.
De Vries, W. (2007–2014). Triturus cristatus and Pelobates fuscus in mainland counties of
Estonia. Results of survey and suggestions for management for 1–2 provinces. Annual
technical reports. MTÜ Põhjakonn & Natura Cerca.
De Vries, W. (2012). Brief results of amphibian survey ECONAT (LIFENAT/LT/581) – Lithuania,
1st week July 2012. Technical report. Amphi Consult.
De Vries. W. (2013). First results of EPMAC Poland, 2013. Educative and Participative Monitoring for Amphibian Conservation. October 2013. Technical report. Natura Cerca.
De Vries, W. (2013a) http://www.naturacerca.es/knoflookpad.html. On the habitat of Pelobates fuscus in Europe.
De Vries, W. & M. van de Loo (2015). On the results of landscape monitoring regarding
amphibians in northeastern Poland. www.epmac-europe.com
Delft, van J. J. C. W., R. C. M. Creemers & A. Spitzen-van der Sluijs (2007). Basisrapport Rode Lijsten
Amfibieën en Reptielen volgens Nederlandse en IUCN-criteria. – Stichting RAVON, Nijmegen.
Janse, J. & W. de Vries (2000). Amphibians in part of the Upper Narew River Valley and surrounding area. In: Toad Talk, the Herpetological Bulletin No. 2. pp. 5–9.
Kielgast, J., L. Iversen, M. Hesselsøe (2012). Fieldwork: J. Kielgast, P. F. Thomsen, W. de Vries,
P. Klit Christensen, M. Larsen, L. Chr. Adrados & L. Iversen. Evaluering af eDNA-detektion til
overvågning af vandhulsarter. Pilotstudie af konventionelle feltmetoder og eDNA-baseret
artsovervågning for stor vandsalamander, løgfrø og stor kærguldsmed. Amphi Consult. 2012.
In Danish (Evaluation of environmental DNA detection for pond dwelling species. Pilot study
on conventional methods versus eDNA for Triturus cristatus and Pelobates fuscus).
Loo, M. van de & W. de Vries (2000). On the amphibians in Veisiejai Natural Park and Meteliai
Regional Park in Lithuania. Amphi Consult report.
Nyström, P. & M. Stenberg (2008). Åtgärdsprogram för lökgroda 2008–2011 (Pelobates
fuscus). / Species programme for Pelobates fuscus in Sweden. Naturvårdsverket, Stockholm.
Rapport 5826.
Ottburg, F., B. Crombaghs, W. Bosman, M. Zekhuis, D. Schut, P. van Hoof, R. Struijk,
R. Westrienen, R. Zollingen, H. Jansman & R. Snep (2015). Kan de knoflookpad op termijn
van de intensive care af. / Can we remove Pelobates fuscus from intensive care soon? De
Levende Natuur jr. 116; nr. 1. Januari 2015.
Rannap, R., A. Lõhmus & L. Briggs (2009). Restoring ponds for amphibians: a success story.
Hydrobiologia (2009) 634:87–95.
Rannap, R., T. Kaart, L. Briggs, W. de Vries, L. Iversen (2011). Habitat requirements of Pelobates
fuscus and Leucorrhinia pectoralis. Project report “Securing Leucorrhinia pectoralis and
Pelobates fuscus in the northern distribution area in Estonia and Denmark.” LIFE08NAT/
EE/000257, Tallinn.
http://www.keskkonnaamet.ee/public/galleries/dragonlife/Habitat_requirements_of_P.
fuscus_and_L.pectoralis.pdf. Tallinn, 2011.
Rannap, R., W. de Vries & L. Briggs (2012). Criteria for assessing the favourable conservation
status of Pelobates fuscus. Project Report, DRAGONLIFE LIFE08NAT/EE/000257 “Securing
Leucorrhinia pectoralis and Pelobates fuscus in the northern distribution area in Estonia and
Denmark”. Tallinn 2012.
Rannap, R., T. Kaart, L. Iversen, W. De Vries & L. Briggs (In press). Geographically varying habitat
characteristics of a wide-ranging amphibian, the Common Spadefoot Toad (Pelobates
fuscus), in northern Europe. Herpetological Conservation and Biology.
Rannap, R., A. Lõhmus, L. Briggs (2009). Niche position, but not niche breadth, differs in two
coexisting amphibians having contrasting trends in Europe. Diversity and Distributions 15(4):
692–700.
Rannap, R., M. Markus & T. Kaart (2013). Habitat use of the common spadefoot toad (Pelobates fuscus) in Estonia. Amphibia-Reptilia 34(1) 51–62.
Pelobates fuscus
in the Netherlands in the Dutch special edition of the
national magazine De Levende Natuur. They opened the
discussion, and this reflection together with the ongoing
shifts, the enormous amount of people and organizations
involved and concerned with the species, indicates that
there must be a future for the surviving populations of
this species in the Netherlands.
In the case of many amphibian species, it has been
possible to shift population tendencies from near extinc
tion towards strong metapopulations, by facilitating
suitable habitat conditions (Rannap et al., 2009). Another
positive example of the recuperation of nearly extinct
52
Pelobates fuscus
Yellow-Spotted
Whiteface
Leucorrhinia pectoralis
54
Habitat requirements
of Leucorrhinia
pectoralis
L
eucorrhinia pectoralis is distributed across Central
and Eastern Europe. Its range spans from South
ern Finland in the north to Central Turkey in the
south, and from Mongolia in the east to France in
the west. Despite its wide distribution range, most of the
populations are considered fragmented and isolated (Fos
ter, 1996). Due to habitat destruction, the species is now
considered endangered in many of the EU Member States,
where only small and isolated populations persist (e.g.
Wildermuth, 1991). This has led to the inclusion of the
species in Annexes II and IV of the EU Habitats Directive
(92/43/EEC).
Material and methods
In order to explore the habitat characteristics essential
for L. pectoralis, both the aquatic and terrestrial habitats
of the species were included in the study. We used data
from Estonian project sites only (91 water bodies in total),
because in Denmark the species was found in less than
five water bodies.
We selected the sites in each study area at random
without any prior knowledge of the presence of the spe
cies studied. Sites were omitted if directly interconnected
by waterways with a site already examined. We used the
standard dip-netting method (Iversen et al., 2015) to record
breeding sites. We actively searched for the larvae of L. pectoralis during 45 min at each site by sweeping a handheld
dipnet (frame measurements 40 × 40 cm) through vegeta
tion and surface sediment. We also searched the riparian
vegetation for larvae exuviae. In the process, we recorded
the species as either present or absent at each site and noted
the number of larvae/exuviae.
Along with collecting species data, we also compiled
habitat descriptions. Instead of recording fluctuating
water chemistry variables, we focused on more stable
physical and biological variables. We assessed relevant
habitat characteristics at each study site in relation to the
known habitat dependencies of L. pectoralis (summarized
in Foster, 1996; Sternberg et al., 2000).
0.2
0
-0.2
-0.4
-0.6
Pond type
Pond characteristics
Sediment
Water
Nr ponds
Habit. 50 m (%)
Habit. 500 m (%)
Figure 1. Distribution of different types of water bodies according to the presence of L. pectoralis larvae
number of ponds
Type of water body and aquatic characteristics
The larvae/exuviae of the species were found in 26 % of
the studied ponds in Estonia. Our study demonstrated
that L. pectoralis preferred to breed in lakes and avoided
man-made ponds as reproduction sites (Fig. 1; 2). Lakes
were larger, deeper and with an extensive area of shallow
littoral zone – features which associated positively with
the abundance of larvae. At the same time, the steep
ness of the slopes and shade were negatively related to
breeding site selection (Fig. 2). Breeding site selection
also depended significantly on the sediment type of the
water body: the dragonflies preferred peaty bottom and
avoided muddy bottom. Additionally, water bodies with
clear brownish water and low conductivity were favoured,
while those with muddy water and high conductivity were
avoided for breeding (Fig. 2). Like P. fuscus, L. pectoralis
also avoided shady water bodies for breeding. The larval
abundance of L. pectoralis was positively associated with
vegetation cover (< 0.001). The presence of water mosses
(Sphagnopsida and Bryopsida) also had a positive effect
(r = 0.47, p < 0.0001 and r = 0.39; p < 0.001 respectively)
on L. pectoralis’ breeding habitat selection.
40
30
7%
93%
57%
20
10
With larvae
Without larvae
13%
87%
43%
40%
60%
0
Lake
Man made
Natural
depression
Beaver
flooding
Figure 2. Spearman rank correlations between larval abundance of L. pectoralis and pond characteristics; the stars
denote the statistically significant (p < 0.05) relationships.
Landscape features in the vicinity of breeding ponds
The number of other water bodies in the vicinity of breed
ing sites affected breeding habitat selection and larval
abundance positively. Thus, a dense network of water
bodies is essential for L. pectoralis. Larger lakes and bogs
have to be included in the wetland network. The presence
of bogs and forest in the close vicinity of breeding ponds
was vital for the dragonflies, and shorter distance from
yellow-spotted whiteface
0.4
Natural depression
Lake
Pond
Beaver flooding
Lenght
Width
Area
Shallow area
Max depth
Mean buffer
Average slope
Shadow
Peat
Mud
Clay
Sand
Brown
Clear
Muddy
pH
Conductivity
< 100 m
100–200 m
200–800 m
Dist. to nearest forest
Fields
Ponds
Buildings
Forest
Roads
Bushes
Open area
Meadows
Bogs
Fields
Ponds
Buildings
Forest
Roads
Open area
Meadoes
Bogs
Spearman correlation coefficients
0.6
56
Small natural lakes and beaver floods are optimal breeding habitats for the yellow‑spotted whiteface Leucorrhinia
pectoralis
the forest was also favoured (Fig. 2). At the same time,
buildings and large open areas, such as meadows and
fields, had a negative impact on the dragonflies.
Suggestions for habitat management
In determining the habitat requirements of L. pectoralis,
we used only data from Estonia, because in Denmark we
found only three sites with L. pectoralis larvae during the
inventory in 2010. This dragonfly species has declined
sharply in the westernmost parts of its range and its pre
sent distribution is very patchy (Sahlén et al., 2004). Thus,
knowledge on the habitat demands of L. pectoralis gained
from Estonia would be very useful for planning active
habitat management in Denmark and other Western and
Central European countries (e.g. Germany, France, the
Netherlands, Belgium, etc.).
In Estonia, L. pectoralis preferred larger natural lakes
with extensive shallow littoral zones and large swampy
edges of moor vegetation for breeding. At the same
time, L. pectoralis refrained from reproducing in artificial
man-made ponds created by local people as fish, garden
watering or sauna ponds, which were generally small
and had steep banks. In many areas in Europe natural
lakes surrounded by bogs and swamps have completely
vanished or their number has decreased rapidly. If such
sites still exist, it would be important to preserve them
in as natural a state as possible. On the other hand, when
planning actions for L. pectoralis habitat management,
we should consider creating large wetlands and restor
ing large permanent depressions with depth variation
and extensive littoral zones. In addition, a dense network
of natural water bodies (lakes, bogs, beaver floods, river
flood plains, etc.) is essential for harbouring viable L.
pectoralis populations. Therefore, aquatic habitats should
be created and restored in clusters.
Leucorrhinia pectoralis preferred to reproduce in water
bodies with peaty sediment and avoided water bodies
with mud. Sediment type proved essential for the spe
cies probably due to its influence on water chemistry and
macrophyte communities. Sediment type also indicates
the species’ preference for natural clean water bodies and
avoidance of eutrophicated waters. Thus, when restoring
or creating breeding sites for this species, sediment type
should be taken into account, and agricultural pollu
tion as well as nutrient influx should be prevented. In
accordance with earlier studies, L. pectoralis’ breeding
site selection was strongly associated with the presence
of macrophytes in the water body (Schindler et al., 2003;
Sahlén et al., 2004). Vegetation cover of less than 1 m in
height as well as the presence of Sphagnopsida and Bryopsida mosses associated positively with L. pectoralis’ larval
abundance. Aquatic vegetation has various important
functions for adults and larvae: among other aspects, it
conceals from predators (Askew, 1982), constitutes a sub
strate for egg deposition and larval habitat, and provides
perches for mating and feeding (Buchwald, 1992; Schin
dler et al., 2003). The presence of forest and bogs in the
close vicinity of breeding sites was essential for L. pectoralis, and shorter distance from the forest was favoured.
Forest provides shelter for the adults. At the same time,
open areas and buildings had a significantly negative
influence on breeding site selection. As demonstrated by
Chin and Taylor (2009), dispersal ability in the genus Leucorrhinia was limited by open areas, particularly at short
distances, whereas forest shelters acted as dispersal routes
for the adults. Thus, breeding sites should be created near
woodlands, and large open areas as well as urban areas
should be avoided.
References
• Askew R. R. 1982. Resting and roosting site-selection by coenagrionid damselflies. Advances
in Odonatology 1: 1–8.
• Buchwald R. 1992. Vegetation and dragonfly fauna – characteristics and examples of biocenological field studies. Vegetation 101: 99–107.
• Chin K. S. and Taylor P. D. 2009: Interactive effects of distance and matrix on the movements
of a peatland dragonfly. Ecography 32: 715-722
• Foster, G. N. 1996. Leucorrhinia pectoralis (Charpentier, 1825). – In van Helsdingen, P. J. et
al. (eds). Background information on invertebrates of the Habitats Directive and the Bern
Convention. Part 1 – Crustacea, Coleoptera and Lepidoptera. – European Invertebrate Survey
Leiden: 40292-307
• Iversen L. L., Rannap R., Briggs L. & Sand-Jensen K. (2015): Variable history of land use
reduces the relationship to specific habitat requirements of a threatened aquatic insect.
Population Ecology (In press).
• Sahlén, G., Bernard, R., Rivera, A. C., Ketelaar, R. and Suhling, F. 2004. Critical species of Odonata in Europe. International Journal of Odonatology 7: 385–398.
• Schindler, M., Fesl, C. and Chovanec, A. 2003. Dragonfly associations (Insecta: Odonata) in
relation to habitat variables: a multivariate approach. Hydrobiologia 497: 169–180.
• Sternberg K. and Buchwald R. (2000): Die Libellen Baden-Württembergs Bd. 2, Eugen Ulmer.
• Wildermuth, H. 1991. Verbreitung und Status von Leucorrhinia pectoralis (Charp., 1825)
in der Schweiz und in weiteren Teilen Mitteleuropas (Odonata: Libellulidae). Opusc. zool.
flumin. 74: 1–10.
58
Criteria for the
favourable
conservation status
of Leucorrhinia
pectoralis
L
eucorrhinia pectoralis is distributed across Central
and Eastern Europe. Its range spans from South
ern Finland in the north to Central Turkey in the
south, and from Mongolia in the east to France
in the west. Despite its large distribution range, most of
the populations are considered fragmented and isolated
(Foster, 1996). During the 20th century, L. pectoralis has
decreased dramatically throughout Europe mainly due to
loss of freshwater habitats (Sahlén et al., 2004). Within the
EU, the species is now considered endangered in many
Member States, where only small and isolated popula
tions persist (e.g. Wildermuth, 1991). This has led to the
inclusion of the species in Annexes II and IV of the EU
Habitats Directive (92/43/EEC).
Determining the criteria for assessing the favourable
conservation status of L. pectoralis in Estonia and Den
mark has been one of the targets of the LIFE-Nature pro
ject “Securing Leucorrhinia pectoralis and Pelobates fuscus in
the northern distribution area in Estonia and Denmark”
(LIFE08NAT/EE/000257). The LIFE-Nature project has
generated a substantial amount of information on the
Favourable conservation status
The following description of the favourable conservation
status of L. pectoralis is based on the presence of the species in relation to the aquatic and terrestrial habitat, and
on population structure (metapopulations or source-sink
populations).
During the DRAGONLIFE project, we observed two
different types of population structure of L. pectoralis:
1. Source-sink populations consisting of breed-
ing sites that produce a large number of individuals
that disperse out into neighbouring habitats. These are
found together with breeding sites with a smaller effective population size, which produces a small number of
individuals that rarely disperse. Unpolluted larger natural
lakes (> 1 ha) were the most common source populations
in these areas. In Estonia, beaver floods could also hold
large populations of L. pectoralis. The “sink” breeding sites
typically consisted of small ponds and water bodies.
2. Local metapopulation structures and isolated populations, where the species is distributed across landscapes
occupying a small number of breeding habitats. In these
population structures, the large source lakes were missing
and L. pectoralis only persisted in smaller water bodies. Due
to the species’ great dispersal potential, local populations
were within the potential migration distance from other
local populations. This means that they should not be
regarded as isolated populations per se, but rather as local
populations within a larger regional metapopulation.
The criteria for assessing the favourable conservation status of L. pectoralis differ according to the type of
population structure.
Source-sink populations
In source-sink populations, the large breeding sites are the
most important component. Adults succeed in dispersing
from these sites to the surrounding habitats, and the long-
ecological requirements of the species. This information is
applied in the specific conservation actions conducted by
the project. Additionally, the knowledge has great value
in determining the factors that the conservation efforts of
the species should address in order to achieve favourable
conservation status across the EU.
In the framework of the LIFE project, Estonian and
Danish experts have been working simultaneously towards
developing the criteria for assessing the favourable conservation status of L. pectoralis. This work is based on several
activities already carried out by the project. The results of
the evaluation of aquatic and terrestrial habitat characteristics gave a better understanding of the species’ habitat
requirements. This action provided new knowledge on the
preferable breeding sites and terrestrial habitat components
of L. pectoralis, which are closely connected to the criteria for
assessing the favourable conservation status of L. pectoralis.
60
term persistence of the species is secured within the sites.
The small sites also act as breeding sites by themselves, but
might be dependent on receiving individuals from neigh
bouring source sites. These sites act as stepping-stones
between source sites and as potential refuge areas.
• The population must have annual stable breeding suc
cess in at least two larger source lakes (lakes or beaver
floods > 1 ha).
• There should be at least four smaller breeding sites
within the vicinity of a source lake.
• Breeding sites should be interconnected within the
common dispersal distance of the species (e.g. should
not be more than 2 km apart).
• Breeding waters must have naturally clean water (low
conductivity) and an extensive shallow zone (water
depth up to 30 cm) of sunexposed vegetation along the
banks. Maximum water depth should be at least 1.5 m,
and the preferred sediment type for L. pectoralis is peat.
• Terrestrial habitat must contain forest in the nearby
surroundings and in the vicinity of the breeding pond.
Forest acts as shelter for breeding adults and a feeding
area for maturing individuals.
• Intensive agriculture in the close surroundings of
breeding sites must be avoided.
• Habitat components must be safeguarded in the area
where the population occurs.
• According to information gained from the LIFE proj
ect, the effective population size should be at least 400
adults, which means that a population must count at
least 800 adults.
Local metapopulation structures
and isolated populations
In these populations, the large stable source sites for
breeding are absent. A population persists in a closely
interconnected network of smaller breeding ponds. The
turnover rate of these sites is high and the species persists
with a lower number of individuals since the large source
lakes are missing. This implies that there has to be much
exchange of individuals between breeding sites, which is
enhanced by high connectivity between the sites.
• Each sub-population must have annual stable breed
ing success in at least 4–5 ponds.
• The distance between interconnected breeding sites
should not exceed 500 meters.
• Breeding waters must be large with naturally clean
water (low conductivity) and an extensive shallow
zone (water depth up to 30 cm) of sunexposed vegeta
tion along the banks. Maximum water depth should
be at least 1.5 m, and the preferred sediment type for
L. pectoralis is peat.
• Terrestrial habitat has to contain forest in the nearby
surroundings and in the vicinity of the breeding pond.
Forest acts as shelter for breeding adults and a feeding
area for maturing individuals.
• Intensive agriculture in the close surroundings of the
breeding sites must be avoided.
• According to the information gained from the LIFE
project, the effective population size within a subpop
ulation must be at least 200 adults, which means that
the population must count at least 400 adults.
Effects of habitat
management on
Leucorrhinia pectoralis
Riinu Rannap, Lars L. Iversen, Timo Torp
L
eucorrhinia pectoralis is the largest of the five
European species in the genus and is distributed
throughout Central and Northern Europe (Dijk
stra and Lewington, 2006). The species primarily
inhabits sun-exposed mesotrophic and slightly eutrophic
waters with well‑developed riparian and aquatic vegeta
tion (Schorr, 1990; Sternberg et al., 2000). The larvae are
aquatic with adult emergence between spring and early
summer (Dijkstra and Lewington, 2006). During the 20th
century, L. pectoralis has dwindled dramatically mainly
because of the destruction of freshwater habitats (Sahlén
et al., 2004). Currently, the populations of the species are
small and isolated, often depending on small freshwater
ponds and lakes. Thus, the species is listed in Annexes II
and IV of the EU Habitats Directive (92/43/EEC). Despite
the declining population trend and the ongoing habitat
destruction, the species has received little attention from
nature conservationists so far and large-scale habitat res
toration is yet to be carried out for the species in Europe.
The sites selected for the project were Natura 2000
sites, covering the majority of the L. pectoralis’ distribution
range in Estonia and the northeastern distribution range
in Denmark. In the very first year of the project, we con
ducted a large‑scale inventory in all project sites to detect
the breeding sites of the species. Based on the results of
the pond inventory, we concluded that L. pectoralis was a
rather common and numerous species in southern and
eastern Estonian project sites (in Karula NP, on Piirissaar
Island and in Emajõe‑Suursoo NR). Therefore, we target
ed pond construction in these sites mainly at P. fuscus. The
species was less numerous in the project sites in northern
62
57,78
57,76
57,74
57,72
57,70
57,68
57,66
26,35
26,40
26,45
26,50
26,55
26,60
Figure 1. Distribution of
inventoried water bodies.
Red circles – water bodies
without larvae/exuviae of
L. pectoralis; black crosses
–water bodies with larvae/
exuviae of L. pectoralis
(Karula NR is zoomed in).
Estonia, and there we targeted pond construction mainly
at L. pectoralis. In Denmark, we found L. pectoralis breeding
ponds in two isolated project sites, where the species was
present in very low numbers. Thus, habitat management
in Denmark focused on boosting and securing the two
existing breeding sites by pond management efforts. In
addition, pond management was conducted in the project
sites situated in‑between the two existing populations in
order to create potential breeding sites for L. pectoralis. The
goal was to create new breeding sites for the species and
stepping-stones between the two isolated populations in
northeastern Denmark.
× 40 cm) through vegetation and surface sediment.
We also searched the riparian vegetation for larval
exuviae. In the process, we recorded the species as either
present or absent at each site.
Based on the results of the pond inventory, we con
cluded that L. pectoralis was a rather common and numer
ous species in southern and eastern Estonian project sites
(in Karula NP, on Piirissaar Island and in Emajõe‑Suur
soo NR). Therefore, we targeted pond construction in
these sites mainly at P. fuscus. The species was less numer
ous in the project sites in northern Estonia, and there we
targeted pond construction mainly at L. pectoralis.
Habitat management conducted
during the project
During the pre-restoration inventory in June 2010, one
trained entomologist checked 91 natural and man-made
ponds, including small lakes, natural depressions, beaver
ponds, cattle ponds, garden ponds, sauna ponds and
ponds historically used for flax soaking.
The standard dip-netting method (Iversen et al., 2015)
was used to record breeding sites. We actively searched
for the larvae of L. pectoralis during 45 minutes at each site
by sweeping a handheld dip‑net (frame measurements 40
We conducted pond management (pond restoration or
creation) in the autumns of 2010–2014 (after the repro
ductive period of most water organisms). In Estonia, a
total of 117 ponds were restored or created anew: 63 in
Karula NP, 10 on Piirissaar Island, 7 in Emajõe-Suursoo
NR, 12 in Mõdriku-Roela and Porkuni LR, 5 in Neeruti
LP, 6 in Lasila NR, 11 in Lahemaa NP and 3 in Varangu.
In Denmark, a total of 54 ponds were restored or created
In 2010, the larvae/exuviae of the species were found in
26 % of all studied water bodies in Estonia. After pond
construction, the species reproduced in 17.5 % of the
restored or created water bodies in project sites. We
established during the post-restoration inventory that
L. pectoralis preferred to breed in lakes and beaver floods.
The lakes were larger, deeper and with extensive areas of
shallow littoral zone – features which associated posi
tively with the abundance of larvae. The shallow vegeta
tion growing along the lake perimeter acts as both larval
feeding habitat, larval emergence site, and resting and
Yellow‑spotted whitefaces breeding
egg-laying site for the adults (Sternberg et al., 2000; Wil
dermuth, 1992). Therefore, this vegetation type supports
the major stages and activities of the species’ life cycle.
As there was a large variety of natural water bodies, such
as small lakes, beaver floods and meanders available in
our project sites, L. pectoralis used the constructed ponds
more as stepping-stones. However, it is known that in
areas without larger natural water bodies and wetlands,
L. pectoralis can sustain viable populations within systems
of exclusively smaller ponds in several areas (Toth, 1983;
Dolný and Harabiš, 2012).
References
Dijkstra, K.-D. & Lewington, R. (2006) Fieldguide for identifying dragonflies of Great Britain
and Europe. British Wildlife Publishing, Dorset.
Dolný, A. & Harabiš, F. (2012) Underground mining can contribute to freshwater biodiversity
conservation: Allogenic succession forms suitable habitats for dragonflies. Biol Conserv, 145,
109–117.
Iversen L. L., Rannap R., Briggs L. & Sand-Jensen K. (2015): Variable history of land use reduces
the relationship to specific habitat requirements of a threatened aquatic insect. Population
Ecology (In press).
Sahlén, G., Bernard, R., Rivera, A. C., Ketelaar, R. & Suhling, F. (2004) Critical species of Odonata
in Europe. Int J Odonatol, 7, 385–398.
Schorr, M. (1990) Grundlagen zu einem Artenhilfsprogramm Libellen der Bundesrepublik
Deutschland. Ursus Scientific Publishers, Bilthoven.
Sternberg, K., Schiel, F.-J. & Buchwald, R. (2000) Leucorrhinia pectoralis. Die Libellen BadenWürttembergs. Band 2 Großlibellen (Anisoptera), (eds. Sternberg, K. & Buchwald, R.), pp.
415–427 Literatur. Verlag Eugen Ulmer, Stuttgart.
Toth, S. (1983) Libellen und ihre Biotope im Bakony-Gebirge. Folia musei historico-naturalis
Bakonyiensis, 1983, 45–54.
Wildermuth, H. (1993) Populationsbiologie von Leucorrhinia pectoralis (Charpentier) (Anisoptera: Libellulidae). Libellula, 12, 269–275.
at sites designated for L. pectoralis (5 in Allerød, 24 in Hill
erød and 25 in Gribskov).
Since the majority of the Danish management actions
were conducted in 2013 and 2014, we expect that the
effect on the Danish populations of L. pectoralis will be
seen, at the earliest, by the summer of 2016 and onwards.
This is partly due to: (1) the time needed for adequate
vegetation to develop after pond management; (2) the fact
that the larvae of L. pectoralis take two years to develop.
Hence, potential breeding success in new ponds can only
be assessed a minimum of two years post management;
in addition, some of the Danish sites were considered
as stepping‑stones / new breeding areas, and the colo
nisation of these areas is expected to happen post the
completion of the DRAGONLIFE project. Therefore, we
evaluated the effects on habitat management using only
the results gained from the Estonian project areas.
When constructing the ponds, we restored and cre
ated water bodies no more than 1 km from the existing
source (e.g. a lake, meander, beaver flood). Land cover
in the surroundings of constructed ponds was mainly to
consist of a mosaic of (semi)natural grasslands and forest.
Experienced experts also guided each pond construction
in the field. We used excavators for pond digging. After
construction, the ponds filled with rainwater, and we
allowed colonization and succession to take their course.
The post‑restoration monitoring took place in 2014–2015.
As L. pectoralis lays eggs in ponds with submerged vegeta
tion (Sternberg et al., 2000; Wildermuth, 1992), the moni
toring included ponds that were at least three years old.
Thus, 40 ponds were investigated. Each pond was visited
once and examined for 45 minutes, using visual counting
of adults, dip-netting of larvae and searching for exuviae.

Protection of the yellow-spotted whiteface and the common

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