ibex report_DEF_rid - Safari Club International Italian Chapter

The “Marmolada Alpine ibex Project”
Safari Club International-Italian Chapter
Amministrazione provinciale di Belluno
Corpo Forestale dello Stato
Regione Friuli-Venezia Giulia
Dipartimento di Produzioni Animali Epidemiologia Ecologia di Torino
Dipartimento di Scienze Animali di Padova
Research report:
may 2006-may 2009
Cover picture by: Maurizio Ramanzin
The “Marmolada ibex project” started in 2006 with the aim of helping the Marmolada colony
to recover after a population crash due to a sarcoptic mange epidemic. 14 adult males coming
from the Jôf-Fuart Montasio(Giulie Alps) colony, which had survived a previous scabies
epidemic, were translocated in 2006 and 2007. The following institutions/corporations took
part in the project:
Safari Club International-Italian Chapter
Financing of monitoring and scientific activities
Amministrazione provinciale di Belluno
Captures and translocation of the ibexes, logistic support
Corpo Forestale dello Stato
Captures and translocation of the ibexes, logistic support
Regione Friuli Venezia Giulia
Supply of ibexes, cooperation in captures
Department of Animal science. University of Padova
Scientific supervision of the project and post-release monitoring
Department of Animal Production, Epidemiology and Ecology. University of Torino.
Scientific supervision of the project and ibex captures; cooperation in ibex monitoring
This report was written by L. Scillitani, E. Sturaro and M. Ramanzin
The following persons took part to field activities and/or data analysis:
Scientific supervison
Maurizio Ramanzin – Department of Animal Science, University of Padova
Luca Rossi – Department of Animal Production, Epidemiology and Ecology. University of
Torino.
Field work supervision
Enrico Sturaro – Department of Animal science, University of Padova
Luca Dal Compare – Department of Animal science, University of Padova
Laura Scillitani – Department of Animal science, University of Padova
Chiara Viale – Department of Animal science, University of Padova
Statistical analyses
Laura Scillitani- Department of Animal science, University of Padova
Enrico Sturaro – Department of Animal science, University of Padova
Data collection
Field assistants: Andrea Aimi, Guido Farenzena, Chiara Viale, Ilaria Angelini
Students: Valentina Berardo Gioli. Luca Carrel, Maria Cavedon, Tommaso Corazza, Daniele
De Barba, Davide De Zotti, Enrico Formentini, Filippo Frasson, Marco Gobbo, Lara Guerra,
Giovanni Orlando, Mattia Pamelin, Vittorio Poli, David Rech, Alberto Saddi, Matteo Sessi,
Luca Schiavon, Daniele Vadagnini, Andrea Zanella.
Logistic support and captures:
Corpo di Polizia Provinciale di Belluno
Corpo Forestale dello Stato
Index
Introduction
1
Captures and characteristics of the sample
1
Monitoring
4
Spatial Behaviour
6
Post-release dispersal
6
Home range size
6
Distribution and movements of ibexes within the study area
10
Distribution of ibexes within the study area
10
Movements between sub-areas
12
Site Fidelity
13
Social Behaviour
15
Group size
16
Group size experienced by males
17
Inter-individual association index between individuals
18
Inter-individual association index between males and females
19
Conclusions and products of the research
20
References
21
Introduction
The Marmolada ibex colony was established in 1978 with the introduction of 6 ibexes coming
from the Gran Paradiso National Park. In 2003 the estimated population size was of about
500 ibexes, but during the winter 2003-2004 the combined effects of a sarcoptic mange
epidemic and harsh weather conditions provocked a dramatic population crash (Monaco et al
2004, Rossi 2006). The Belluno Province and Corpo Forestale dello Stato started a
management action with the scientific supervision of from the Department of Animal
Production, Epidemiology and Ecology of the University of Torino (Prof. Luca Rossi).
Scabietic ibexes were captured and farmacologically treated. In summer 2006 only 110 ibexes
were counted, but the epidemic was almost eradicated.
In 2006 a restocking project, the “Marmolada Alpine ibex project” was started, with the aim
of improving the long term viability of the colony. To this purpose, the translocated ibexes
were all adult males, able to reproduce successfully, with the specific aims of:
1. improving genetic variability. The Marmolada-Monzoni colony was founded by a
small group of animals, which is a well known cause of loss of genetic variability.
Recent studies (Maudet et al. 2002) suggest that the introduction of even a small
number of animals can improve the level of heterozygosity within a population;
2. enhancing resistance to sarcoptic mange. Scabies resistance could be an inheritable
trait (Guberti e Zamboni 2000, Leung e Grenfell 2003). The translocated ibexes came
from the Tarvisio colony, which has recovered from a previous scabies epidemic and
it presently increasing, despite the illness is still present in an endemic phase.
Several different institutions and societies took part in this project. Funding for monitoring
and scientific activities was provided by the Italian Chapter of Safari Club International.. The
Belluno province and Corpo Forestale dello Stato ensured capturing ibexes and logistic
support for field activities. The Regione Friuli Venezia Giulia supplied ibexes to be
translocated and supported their capture. The Department of Animal Science of the University
of Padova and the Department of Animal Production, Epidemiology and Ecology of the
University of Torino supervised the project and ensured post-release monitoring
We provide here the results obtained from a three years post-release monitoring of the spatial
and social behaviour of the translocated ibexes, in comparison with that of local individuals,
in order to describe their process of adaptation to the new area.
This gives an assessment of the short term oucome of the project. In the next years, with a
sufficient time span and adequate sampling, we will be able to verify whether the colony has
improved its genetic variability and its resistance to scarcoptic mange.
Captures and characteristics of the sample
Ibexes were captured from the colony of the Jôf Fuart-Montasio massif, near Tarvisio (UD).
This colony survived and recovered fast from a previous sarcoptic mange epidemic (Rossi,
2006).
Captures were performed using darting guns by trained personnel of Corpo di Polizia
Provinciale di Belluno e del Corpo Forestale dello Stato, under the medical supervision of
veterinarians from Department of Animal Production, Epidemiology and Ecology of the
University of Torino and from Centro di Ricerca e Gestione della Fauna Selvatica
(Ce.Ri.Ge.Fa.S.). Support for handling and transporting ibexes was also provided by
personnel of regione Friuli Venezia Giulia, Department of Animal Science of Padova,
1
Department of Animal Production, Epidemiology and Ecology of the University of Torino
and Italian Chapter of Safari Club International.
All sedated males were blindfolded, aged (from annual horn growth), subjected to
measurement of body morphology, examined for health status and blood sampled by the
veterinarian. They were then ear-tagged, equipped with a radio-transmitter, placed on a
stretcher and carried to the nearest vehicle to be transported into individual wooden cages to
to a stable, where they were housed until transportation to the release site. Images of handling
and transportation are given in figure 1.
b
a
c
d
e
f
Figure 1: Captures of the ibexes in tarvisio: stretcher with a sedated and tagged male a), carrying to the vehicle
b), individual wooden cages and vehicle for transportation to the stable c); ear-tagging d) measurements e) and
release f). (pictures by M. Ramanzin (a, b, c, f), L. Scillitani)
2
Between 19-23 May 2006 9 adult males (5 to 9 years old) were captured on the Jôf FuartMontasio massif. On the 25th of May they were released near “Malga Ciapela” (46° 26’ 13.
05’’ N 11° 51’ 21. 21’’ E) near Rocca Pietore (BL), at about 1,600 m a.s.l. (figure 2). On 15
May 2007 other 5 adult males were released in the same place.
On the 6th and the 7th of August 2007 8 adult local males were captured and radio tagged on
the “Cime dell’Auta” area (Figure 2). Capture procedures were the same as above described,
except that in this case the animals were released on site after tagging.
Figure 2: Study area: the blue star indicates the release site of reintroduced ibexes; the yellow star the capture
site of local animals
Characteristics of captured (translocated and local) ibexes are given in table 1. In addition to
these individuals, 11 other adult males, which had been tagged in a previous project of the
Trento province (Monaco et al 2005), and for we were able to collect a consistent number of
observation, were included in the monitoring (characteristics of these individuals are not
given in table 1).
We recorded no stress related
mortality due to capture and
transportation.
During
the
winter 2008-2009, which was
characterized by exceptional
snow precipitations (figure 3)
two translocated males died
engulfed by avalanches.
Snow depth (cm)
140
120
100
80
60
40
20
0
123456
2006
1011121 2 3 4 5 6
2007
101112 1 2 3 4 5 6 101112
2008
Figure 3: average monthly depth of snow cover. Months are
indicated as January = 1, February = 2, ecc.). Months between
July and September are excluded
Monitoring efficiency was
affected by malfunctions of
some collars, which were
replaced with new ones during
2008 and 2009 (table 2).
3
We hereafter name “local” all local males, “TAR1” the ibexes translocated in 2006, and
TAR2 those translocated in 2007.
Table 1: Ibexes radio-equipped during 2006-2007
ID
MTAR1
M
24/05/06
7
Yellow
MTAR2
M
24/05/06
7
Blue
MTAR3
M
24/05/06
7
Blue
Red
Red
.685
collar replaced
6
Light blue
Green
Blue
.600
collar replaced
Blue
Green
.650
M
24/05/06
Collar
Ear-tag
Frequency
Notes
Left
Right
Yellow Yellow . 420
collar replaced; killed by avalanche
Blue
Blue
.750
MTAR4
Sex Capture date Age
MTAR5
M
24/05/06
9
Blue
MTAR6
M
24/05/06
5
Blue
Yellow Red
.200
brocken collar
MTAR7
M
24/05/06
7
Light blue
Red
Blue
.100
collar replaced
Yellow Blue
.400
MTAR8
M
24/05/06
9
Blue
MTAR9
M
24/05/06
8
Light blue
Yellow Green
Green
MTAR10
M
17/05/07
7
Blue
MTAR11
M
17/05/07
6
Blue
Blue
MTAR12
M
17/05/07
7
Blue
Red
.800
Yellow .050
Yellow .701
collar replaced
brocken collar
MTAR13
M
17/05/07
7
Black
MTAR14
M
17/05/07
8
Blue
Bianco .450
Yellow Orange .275
Green
Green .350
Red
M5
M
07/08/07
7
Black
M18
M
07/08/07
5
Light blue
Blue
killed by avalanche
Blue
collar replaced
Blue
.975
Yellow . 826
Blue
.555
Red
collar replaced
M19
M
07/08/07
5
Black
M25
M
07/08/07
4
Light blue
Bianco
Orange
M31
M
07/08/07
3
Black
M43
M
07/08/07
3
Light blue
Orange
.180
Orange .075
Green .830
M44
M
07/08/07
7
Black
Orange
Blue
M47
M
07/08/07
5
Black
Green
Bianco .726
collar replaced
.136
Monitoring
Monitoring of marked ibexes was conducted by the Department of Animal Science of Padova
University (researchers, PhD students, Master and Bachelor students, and professional field
workers) and from Bachelor and Master students from the Department of Animal Production,
Epidemiology and Ecology of Torino University, with the logistic support of Corpo di Polizia
Provinciale di Belluno and of Corpo Forestale dello Stato.
Ibexes were located by both triangulation or radio-assisted sightings (Kenward 2001), which
consist in following a signal toward its greatest strength to visually identify the animal.
However, in Alpine environments the presence of rocky peaks, cliffs and canals causes
reflection and refraction of radio waves, therefore locations obtained by triangulation
technique may be highly biased (Pedrotti et al., 1995). For this reason, triangulation was used
only in particular circumstances when sightings were impossible (for example when an
animal was into the forest or when visibility was poor due to clouds).
Each sighting was plotted in a orthophotograph of Veneto region (1:10000 scale) and
georeferenced in ArcView© 3.2. For each sighting we noted size and composition (age class
and sex of individuals) of the group in which the monitored ibex/ibexes was/were observed.
To help locating individuals we used binoculars, but individual identification was ensured by
a 60 x magnifier telescope.
4
Sampling effort
Up to 12/5/2009, we totalled approximately 800 days of fieldwork and collected 1618
sightings of marked ibexes in a total of 2639 ibexes sightings. Fieldwork was conducted all
year long, and we tried to obtain at least 5 sightings per month for each radio collared ibex.
The efficiency of monitoring, in terms of number of sightings was reduced during winter
months, because snow depth and/or the risk of avalanches often prevented fieldworkers from
reaching the areas where it was possible to sight ibexes. This problem was more pronounced
during the third year of research, characterized by an exceptional snow abundance (figure 4).
Table 2: number of sightings of radio-collared males
Total
2006
2007
2008
2009
Sightings
Local
TAR1
TAR2
Local
Sightings/individual
TAR1
TAR2
June
July
August
September
October
November
December
January
February
March
April
May
June
July
August
September
October
November
December
January
February
March
April
May
June
July
August
September
October
November
December
January
February
March
April
77
83
149
141
104
107
68
64
74
89
107
108
179
137
132
116
122
60
105
69
73
84
102
202
123
183
135
115
105
132
48
67
66
89
87
31
25
70
63
26
49
31
22
21
22
27
30
69
39
68
65
76
34
54
42
38
46
55
114
66
117
92
84
75
86
26
44
50
58
58
46
58
79
78
78
58
37
42
53
67
80
55
71
62
44
38
27
16
33
14
21
15
28
54
38
38
25
20
14
27
13
12
5
21
16
23
39
36
20
13
19
10
18
13
14
23
19
34
19
28
18
11
16
19
9
11
11
10
13
2,8
3,1
6,4
5,7
3,3
4,5
3,4
3,1
2,3
3,1
3,4
2,1
5,8
3,3
4,5
4,3
5,1
2,6
3,6
3,2
3,2
3,1
3,4
7,1
4,1
7,3
6,1
5,6
6,3
6,1
4,3
3,4
5,0
4,8
4,1
4,7
6,2
8,2
8,1
8,6
6,2
4,6
4,6
5,9
7,4
8,8
5,9
7,8
6,7
4,9
4
3
2
3,4
2
2,3
1,9
3,1
6
4,2
4,2
3
2,2
2,3
3,4
2,6
2
1
3
2,7
4,6
7,8
7,2
4
2,6
3,8
2,5
3,6
2,6
2,8
4,6
3,8
6,8
3,8
5,6
3,6
2,8
3,2
3,8
2,3
4
4
2,5
3,3
May
56
33
14
9
2,8
2,3
2,3
5
Spatial behaviour
Knowledge of how animals use space and how they use the habitat resources within that space
is fundamental to apply correct management and conservation strategies. Many animals
restrict their movement to specific home ranges (Burt 1943; White & Garrot 1990).
According to the classic definition by Burt (1943) the home range of an animal is the area
travelled by an animal for food gathering, reproduction and rearing of offspring. Therefore,
describing size and characteritics of home ranges is a basic question in wildlife biology. A
particularly interesting feature is site fidelity, which is the tendency of an animal either to
return to an area previously occupied or to remain within the same area for an extended period
of time (White e Garrot 1990). Estimating site fidelity is most interesting when dealing with
translocated animals, because it allows to investigate on the adaptation process to the new
environment.
We expected translocated ibexes to show different spatial strategies than local males, because
of their need to explore the new territory and find suitable areas. Quantifying this esploratory
phase was one of the main objective of this project, which we addressed by examining the
post-release dispersal from the release site and by comparing the size of annual and seasonal
home ranges, the patterns of home range use, and the site fidelity to home ranges exhibited by
translocated and local males. .
Post-release dispersal
Translocated animals may disperse from the release site (Maillard et al 1999, Dal Compare
2008 ) and in some cases may abandon it permanently, when the release area is poorly
suitable for the species and nearby better areas and/or populations attract them. In our case,
translocated ibexes showed a post-release spatial instability (see below), but they all
restrained their exploratory movements within the area used also by local males.
The study area was obviously suitable for the species, since the Marmolada ibex colony had
been thriving before the epidemics, but we believe that also the presence of the residual
population prevented the introduced ibexes from displaying wide exploratory movements.
This finding has important management implications, since restocking operations are
suggested as management tools for ibex conservation in the recent discussion on the
possibility of hunting the species in Italy (Tosi G., personal communication)
Home range size
We estimated annual (I year: June 2006 – May 2007; II year: June 2007-May 2008; III year:
June 2008 - May 2009) and seasonal (season 1, “summer”: June-August; season 2 “Autumn”:
September-November; season 3 “Winter and Rutting season”: December-February; season 4
“Spring”: March-May) home ranges .
We employed two home range estimators: Minimum Convex Polygon (MCP) and Cluster
(Kenward 2001, Millspaugh e Marzluff 2003). In both cases we used 95% of the total
locations (the outermost 5% of locations were excluded from the calculation of home range
size to avoid inflated estimates). Home range size was obtained with the Ranges VI software
(Kenward et al., 2003), while statistical comparisons were conducted with SAS 9.1(SAS,
1989). For the analysis we used data collected from June 2006 and April 2009.
6
We used the MCP estimator because it allows to describe the maximum area explored by an
animal and it permits comparisons with other studies. However, this method tends to
overestimate home range size, because it is constructed by drawing the line with the minimum
sum of linkage distances connecting the outermost locations (White and Garrot 1990). Cluster
estimators are built with a nearest neighbour joining rule, based on the distance between
locations (Kenward 2001), and can be really useful to describe the space use by ibexes which
generally use areas connected by corridors (Pedrotti 1995). A comparison between the two
estimators is given in figure 4.
Combining this two
methods allowed us to
obtain an estimate of
both the minimum
(Cluster)
and
the
maximum
(MCP)
areas used by the
ibexes.
Figure 4: A comparison between the two home range estimators employed in
this study: MCP (in red) and Cluster (in blue).
Details on statistical
comparisons are given
in box 1 for the
interested
readers,
while the results are
discussed
in
the
following sections.
Box 1: statistical analysis of home ranges
A preliminary analysis of variance (ANOVA) revealed a highly significant difference between the
two home range estimators both for annual home ranges (F1,282=14.31; p<0.001) and seasonal
home range (F1,371=20.55, p<0.0001). Therefore, all the following analyses were carried on
separately for MCP and Clusters.
Since different individuals can behave differently (Börger et al 2006), we used mixed models,
which took into account random effects due to individual variability (PROC MIXED procedure,
SAS 1999). These effects were, in all the analyses, an important source of variability.
The ANOVA’s of annual home range size showed a highly significant effect of the origin of the
ibexes (“TAR1” = ibexes translocated in 2006, “TAR2” = ibexes translocated in 2007, and
“Local” = males from the Marmolada colony) on both MCP (F2,36=12.30, p<0.001) and Cluster
(F2,36=4.08, p<0.05) estimates. The effect of research year was highly significant with MCP
(F2,56=13.54, p<0.001) and very close to significance with Cluster (F2,56=3,05; p=0,0554). The
interaction between animal origin and research year was highly significant for MCP (F7,53=8.66,
p<0.001) and significant for Cluster (F7,53=2.76, p<0.05).
The ANOVA of seasonal home range size showed significant effects of: season (MCP:
F3,165=29.24, p<0.001; Cluster: F3,165=28.59, p<0.001), research year (MCP: F2,165=20.74, p<0.001;
Cluster: F2,165=2.95, p=0.055), animal origin (MCP: F2,165=12.19, p<0.001; Cluster: F2,165=16.00,
p<0.001), and by the interaction between all this factors, which is highly significant (MCP:
F28,144=9.41, p<0.001; Cluster: F28,144=6.88, p<0.001).
7
Annual home ranges
Size of home ranges used by
local males remained fairly
constant during the three years of
monitoring (figure 5). Tarvisio
males used much larger home
ranges than local males during
2006 (year 1) and 2007 (year 2),
and only in 2008 (year 3)
reduced the size of the areas used
to values similar to those of local
males.
Seasonal home range
Local males occupied areas of
similar size through all the
seasons and in all the research
years (figure 6). During 2006
and 2007 (years 1 and 2 after
8
Area (ha)
2000
1500
1000
500
0
Local Tar1
Local Tar1 Tar2 Local Tar1 Tar2
Year 1
Year 2
Year 3
1200
Area (ha)
1000
800
600
400
200
0
Local Tar1
Local Tar1 Tar2 Local Tar1 Tar2
Y ear 1
Y ear 2
Y ear 3
Figure 5: annual home range size (ha) estimated by MCP (above)
and Cluster (below). Note the different scales of the Y-axis.
1800
Local
1500
TAR1
1200
TAR2
900
600
300
Year 1
Year 2
800
DecFeb
SepNov
JuneAug
Marc
h-
DecFeb
SepNov
JuneAug
Marc
h-
DecFeb
SepNov
JuneAug
0
Year 3
Local
TAR1
600
TAR2
400
200
0
JuneAug
SepNov
DecFeb
Marc
hJuneAug
SepNov
DecFeb
Marc
hJuneAug
SepNov
DecFeb
Annual home range sizes
determined in this study are
similar to those reported for
reintroduced populations of
Alpine ibex (Michallet 1994,
Terrier e Rossi 1994, Pedrotti
1995, Mustoni et al 2000), while
the areas estimated for local
males are comparable to those
reported by Parrini et al. (2003)
in the Gran Paradiso National
Park.
2500
area HR (ha)
Interestingly,
the
animals
released in 2006 (TAR1) roamed
over larger areas than local
males for two years, while the
males translocated in 2007
(TAR2) diminished their home
range size one year after release.
3000
area HR (ha)
Reintroduced populations are
often characterized by a marked
tendency to roam in large areas
in order to explore the new
environment (Terrier e Rossi
1994). This behaviour can cause
an increase in home range size
estimates,
especially
MCP
(Pedrotti, 1995; Tosi et al.,
1996), as is confirmed also by
our data.
3500
Year 1
Year 2
Year 3
Figure 6: seasonal home range size (ha) estimated by MCP
(above) and Cluster (below). Note the different Y-axis scales.
release) translocated ibexes used larger areas than local males in summer and Autumn, while
during the 2008 (year 3) they behaved similarly to local males. In all three years, winter and
spring home range sizes of Tarvisio ibexes were comparable to those of local males.
Several studies (Pedrotti 1995, Girard 2000, Parrini et al., 2003) report a seasonal variation in
home range size of Alpine ibex. During summer ibexes use larger areas, while in winter,
when snow cover limits movements and rutting season attracts both sexes in suitable areas,
they occupy smaller home ranges. In our case, however, the summer increase in home range
size was much more marked for translocated than for local ibexes. This indicates that postrelease exploratory movements are more pronounced when climate is favourable and food
resources abundant. As for annual home ranges, the ibexes released in 2007 seemed to settle
after one year from release, while those released in 2006 seemed to need two years.
Comments
Although the Tarvisio ibexes did not disperse outside the Marmolada colony, the analysis of
home ranges demonstrates
that they showed a postrelease spatial instability,
roaming over larger areas than
local males. However, this
exploratory behaviour was
seasonally restricted, being
displayed only in summer and
autumn, when climate is
favourable and food abundant.
In winter and spring, no
differences in home range size
between local and introduced
ibexes were observed.
Figure 7: different individuals adopt different spatial strategies: a
comparison between mTAR2 (above) and mTAR3 (below). In blue
home ranges occupied in 2006, in red those of 2007 and in green
those of 2008. Yellow dots show locations. Note that scales of the two
maps differ.
The Tarvisio ibexes stabilised
their home ranges to sizes
similar to those of local ibexes
within one or two years after
release. It is interesting to
notice how TAR2 ibexes
seemed to stabilize faster than
TAR1. There were no
differences in age and body
size,
the
main
factors
affecting social behaviour of
male ibex, between the
animals translocated in 2006
and those released in 2007.
Therefore we don’t have any
clear explanation for this
phenomenon. Two hypothesis
can be made, but none of
them has been adequately
tested in the field. The first
one is that TAR2 ibexes might
have associated faster with
local males because they
9
recognized the males translocated in the previous year. The second hypothesis is that TAR 2
males were individually more prone to adapt to a new environment.
Individual variability plays in fact an important role in spatial behaviour, as was highlighted
by the statistical analysis (see box 1), and as is exemplified by the behaviour of two different
males, mTAR2 and mTAR3, both released in 2006 (figure 7). mTAR2 in the summer
following the release occupied mainly the area between Piz Guda and Padon, while during the
second summer it explored also Franzedaz, Ombretta and Cime d’Auta. In the third summer
he went back to the places he attended the first year. On the contrary male mTAR3 occupied
the same areas during the first two summers (Ombretta, Franzedaz e Cime d’Auta). On the
third summer he chose to remain in the area of Cime d’Auta.
Distribution and movements of ibexes within the study area
Home range analysis showed how translocated ibexes tended to use larger areas, indicating a
spatial instability. In this paragraph we analyze more in detail the spatial strategies of ibexes,
by analyzing their rate of movement and quantifying the areas they use more frequently.
Distribution of ibexes within the study area
Ibexes (local and introduced) did not disperse uniformly throughout the study area, but they
showed a patchy distribution, where areas more intensively used were separated by areas
seldom or never used. Based on morphological and land use features that are known to affect
habitat suitability for ibex, and on the spatial distribution of sightings, we divided the total
study area in different sub-areas (figure 8). We determined 10 sub-areas in summer and 12 in
winter, when the presence of snow cover limits the connections between two sub-areas.
Figure 8: sub-division of the study area in the 10 sub-areas used in summer
10
We assigned each sighting to its sub-area (Geoprocessing extension in Arc view 3.2) and then
compared the sub-areas most used by local and introduced males during summer and winter
(figure 9).
Local
100%
Tar1
Tar2
80%
60%
40%
20%
Padon
Sasso Bianco
Piz Guda
Ombretta
Franzedaz
CimadellUomo
Auta
Sasso Bianco
Padon
Ombrettola
Ombretta
Year 2
Pianezze- Cime Pezza
Year 1
Franzedaz
Contrin
CimadellUomo
Auta
Other areas
Piz Guda
Padon
Ombrettola
Ombretta
Franzedaz
Auta
CimadellUomo
0%
Year 3
90%
80%
70%
60%
50%
40%
30%
20%
Year 1
Year 2
Pale del Menin
Ombretta
Franzedaz
Cime Auta- Becher
Piz Guda
Pianezze- Cime Pezza
Pale del Menin
Ombrettola
Ombretta
Franzedaz
Contrin
Cime Auta- Becher
Piz Guda
Pianezze- Cime Pezza
Pale del Menin
Padon
Ombretta
Franzedaz
Cime Auta- Becher
0%
Cima uomo
10%
Year 3
Figure 9: frequency of use (% of sightings) of different sub-areas by ibexes of different origins during
summer (above) and winter (below)
During summers of all years, local males strongly preferred the “Cime d’Auta” sub-area,
where wide alpine grasslands can be found (figure 10). The Tarvisio ibexes released in 2006
dispersed in a greater number of sub-areas, especially in the first summer after release, and
only in the subsequent years they tended to concentrate, although less strongly than local
males, in the “Cime d’Auta sub-area”. The Tarvisio ibexes released in 2007 showed a
preference for this sub-area already in the summer of the release year, and in 2008 they used it
almost exclusively.
11
During winter, use of the different areas by local and introduced males was similar. This
pattern is in accord with that above observed for home range size.
Figure 10: a group of local males in the “Cime d’Auta” alpine grasslands. Picture by L. Dal Compare
Movements between sub-areas
In addition to the tendency to use a
smaller or a greater number of subareas, another indication of spatial
instability may be obtained by
examining the frequency with which
an individual moves from a sub-area
to another.
To this purpose, we calculated the
number of times (rate of change)
each monitored ibex shifted from a
sub-area to another within each
season. Comparisons were made
using logistic regression models (see
figure 11 for some statistical details).
We first compared the rate of change
(in all seasons) of local with that of
translocated males (figure 12). Both
TAR1 and TAR2 ibexes tended to
change sub-area more often than
local males, although this tendency
did not reach statistical significance.
12
6
5
4
3
2
Local
1
0
Tar1
Tar2
Figure 11: relative probability of change of sub-area (odds
ratio) of the translocated ibexes in comparison to local
males. The rate of change of local ibexes is taken as
reference value and is = 1; higher values indicate a
proportionally higher probability of change. For instance, an
odd ratio = 2 indicates that average rate of change is double
than that of reference. Vertical bars indicate individual
variability. If they overlap 1 the difference in the average
odd ratios is not statistically significant
We then compared the rate of
change (all ibexes) between
seasons (figure 12), using summer
as the reference season.
2,0
1,5
Summer
1,0
0,5
0,0
Autumn
Winter
Spring
Figure 12: seasonal odds ratio for rate of change of sub-areas.
See caption of figure 11 for explanation
In winter and spring, ibexes
reduced significantly their rate of
change, i.e they tended to remain
longer in the same sub-area, as
respect to summer and autumn,
when
they
shifted
more
frequently between sub-areas.
Site fidelity
A common way of measuring site fidelity, e.g. the tendency of an individual to use the same
area over a certain period, is to calculate the overlap beyween subseuqnt home ranges of the
same individual. We computed the overlap between annual home ranges (overlaps betweens
years 1 - 2, years 2 - 3 and years 1 – 3) and summer home ranges (overlap between the home
ranges of the same season in years occupied in years 1 - 2, years 2 - 3 and years 1 – 3, if
available). The overlap was quantified by using the following equation:
S = C*100/(A + B – C)
where:
S = overlapping percentage
A = Home range A area
B = Home range B area
C = overlapping area between A and B
Given the non-normal distribution of data, even when subjected to log- and other
transformations, statistical comparisons were made by means of non-parametric tests
(interested readers may see box 2 for details).
Box 2: statistical analysis of percentage overlap of home ranges
The percentage of overlap between annual home ranges was strongly affected by origin of the
animals for Cluster (Kruskal-Wallis test: H = 10.65, df = 2, p = 0.005), but not for MCP estimates
(Kruskal-Wallis test: H = 1.37, df = 2, p = 0.50).
Using only Cluster estimates, the percentage of overlap was not affected by years compared for
local males (Kruskal-Wallis test: H = 2.31, df = 2, p = 0.315), while it was significantly affected
for TAR1 (Kruskal-Wallis test: H=6.195, df= 2, p=0.045). TAR2 ibexes were not examined
because they had only 1 combination of years (2-3).
We compared the overlap between summer home ranges in local and TAR1 males. The
differences between the two groups were significant, both for Cluster (Mann-Whitney test: U =
48.50, p < 0.001) and MCP (Mann-Whitney test: U = 128.00, p < 0.01. TAR2 ibexes were not
examined because they had only 1 combination of years (2-3).
13
60
75
50
overlap percentage
Overlap between annual home range
The overlap of annual MCP home
ranges did not differ between local and
translocated animals (data not shown).
With cluster home ranges, local males
had a higher inter-annual overlap than
TAR1, but a lower overlap than TAR2
(figure 13). However, the overlap
estimated for TAR2 refers only to years
2 and 3, while for local and TAR1 males
we had more data: the smaller sample
size of TAR2 could have affected the
results.
40
30
20
10
0
LOCAL
The median overlap between the home
ranges of the first and the third year has
an intermediate value between those of
years 1-2 and 2-3 overlaps, and the size
of the relative box in figure 15 indicates
that differences between individuals
were much higher.
This further emphasizes the importance
of
individual variability in spatial
behaviour, as above reported (see figure
8). Some individuals used the same subareas or explored neighbouring subareas in all 3 years, while other
individuals, in one or two years but not
in all years, roamed over larger and/or
distant areas.
14
TAR2
Figure 13: Overlap percentage between cluster (box
and whiskers diagram) in animals of different origin
60
43
50
overlap percentage
In the first two years after release,
TAR1 males roamed over larger areas
than in the third year, when they
stabilized in a smaller area. As a
consequence,
also
the
overlap
percentage of the third year with the
others decreased.
TAR1
animal's origin
40
30
20
10
0
Years 1-2
Years 1-3
Years 2-3
60
50
overlap percentage
Local males maintained a similar
overlap of their annual Cluster home
ranges from year 1 to year 3 (figure 14).
Therefore, their site fidelity did not
change with time. On the contrary,
TAR1 males (TAR2 were not included
in years comparisons because we had
only years 2 and 3 available) showed a
significantly higher overlap between
years 1-2 than between year 1-3 and 2-3
(figure 14).
40
86
30
20
10
63
0
Years 1-2
Years 1-3
Years 2-3
Figure 14: Overlap of annual Cluster home ranges (box
and whiskers diagram) in local (above) and
TAR1(below)
Overlap between summer home ranges
percentage of overlap
80
60
40
Summer is the season when ibexes
tend to increase their movements,
using larger home ranges (Pedrotti
1995, Girard 2000, Parrini et al.,
2003). This was also the season, as
above reported, when exploratory
movements of translocated ibexes
were more pronounced, causing a
very remarkable increase in home
range size.
20
We thus compared the overlap
between summer home ranges
(summers of years 1-2, 1-3 and 2-3)
0
of local and TAR1 males. With
LOCAL
TAR1
both MCP and Cluster estimates,
animal origin
local males showed a higher site
fidelity towards their summer
Figure 15: Percentage of overlap between summer home
ranges (box and whiskers diagram) observed in animals of
ranges than TAR1 males (figure 15
different origin.
gives the results for Cluster home
ranges; those of MCP were similar and not shown). Therefore, exploratory movements of
translocated ibexes were directed to different areas in different years.
Comments
Alpine ibex has been described as a species with a high site fidelity, which occupies stable
seasonal ranges (Girard 2000, Tosi e Pedrotti 2003). Our analyses of frequency of use of
different sub-areas, rate of movements between sub-areas, inter-annual overlap of annual and
summer home ranges) are in general accord with this pattern for local ibexes. On the contrary,
translocated ibexes showed a lower site fidelity in the first two yeas after release, which is
most probably due to exploratory movements, since in the third year they behaved more
similarly to local ibexes. These results, combined with those above described for home range
size, suggest that adaptation of spatial behaviour to the new environment in which
translocated individuals are released is a slow and gradual process.
All parameters linked to exploratory movements showed a seasonal pattern, with a marked
increase of spatial instability in summer/autumn, and a decrease in winter/spring, when there
were no differences between local and introduced ibexes. Evidently, animals do not face risks
and/or costs linked to the need of exploring the new area when climate is harsh and resources
scarce.
Social behaviour
As many other ungulate species, Alpine ibex is characterized by sexual segregation, and
outside the rutting season males and females segregate occupying different habitats (Mustoni
et al. 2002, Tosi e Pedrotti 2003). In addition, a feature of ibex social behaviour is the high
gregariousness of males, that may aggregate in groups of variable and often remarkable size,
in which social interactions are apparently regulated by age and body size (Willisch e
Neuhaus 2008).
We analysed the database obtained form the sightings collected during the three years of
monitoring with the objective of describing the gregarious tendency of the two sexes in the
15
colony, but mainly of understanding if translocated males integrated in the Marmolada
colony, interacting with local ibexes. Social interactions are important not only per se, but
also because they might influence the spatial behaviour and the length of the spatial instability
of the released animals.
To this purpose, we examined the group size experienced by ibexes of different origin and
how they associated individually with each other.
Group size
The observed group size in relation to group type in the Marmolada colony in the whole
research period is reported in figure 16. Male groups are composed by males of different ages,
females groups are formed by females with kids and yearlings, and mixed groups are
composed by females (also with kids
and yearlings) and males.
40%
The most frequent group size was 2 -5
1
2-5
6-10
11-20
>20
animals for female groups (58% of
30%
observed groups), 1 individual for male
groups (47%), and again 2-5 individuals
for mixed groups (41.5%). Toïgo et al
20%
(1995), in the colony of Belledonne
massif (France) reported a similar
10%
distribution for female groups, but
observed less frequently solitary males
and more frequently mixed groups of 60%
10 individuals. However, group size in
Females
Males
Mixed
ibex is also related to variation in
Figure 16: Group size of three types of groups: allpopulation density (Toigo, 1996), and female, all-male and mixed
our result is probably affected by the
“altered” social behaviour exhibited by translocated ibexes, as we will discuss later.
Group size shows also seasonal
variations (Toigo et al., 1995; Pedrotti
1995) which may differ between sexes
due to sexual age class segregation
(Francisci et al., 1985; Villaret e Bon
1995; Girard, 2000).
18
16
14
12
10
8
6
4
2
0
Females
Males
Also in the Marmolada we observed a
Summer
Autumn
Winter
Spring
seasonal variation in group size (figure
17). Solitary females were easy to Figure 17: Seasonal variation in mean group size in
groups of female and groups of males in the Marmolada
encounter in late spring, when they colony
withdraw in secluded sites to give birth
(35% of sighted females in may-june were alone), while 71% of males were seen alone in
December-January, during rutting season when they become solitary in relation to mate
competition (Mustoni et al, 2002). The largest groups were recorded, in both sexes, during
summer.
16
Group size experienced by males
The frequency distribution of observed group types, although it accurately describes the
perception of the human observer, does not describe the size of a group in which an average
individual lives (Jarman, 1974; Putman, 1996). According to Jarman (1974), the group size
experienced by an average individual (“typical group size”) is better described by calculating
the frequency distribution of all sightings of a given sex/age category (e.g. male or female) in
groups of different size, regardless of the group type. We therefore calculated the group size
experienced by TAR1, TARr2 and local males (of the same age class as TAR1 and TAR2).
All the statistical comparisons were made with a χ2 test with Bonferroni confidence intervals.
70%
60%
50%
40%
30%
20%
10%
0%
1
2-5
6-10
11-20
>20
I year
a
70%
60%
50%
It is interesting to notice how TAR2
ibexes behaved differently from
TAR1: although they used less
frequently than local males large
size groups, they were less often
solitary, and joined more often
large groups.
40%
30%
20%
10%
0%
1
2-5
6-10
11-20
During the first year after release,
translocated TAR1 males tended to
join small groups (2-5 components)
or to be solitary, while local males
used more frequently groups
formed by 11 to 20 individual, and
were often observed in groups
composed by more than 20
individuals (figure 18a). This lower
gregarious tendency of TAR1 was
observed also in the second and
third year after release (figure 18
b), although they showed an
increased use of groups composed
by more than 10 individuals.
>20
II year
We recorded an increase in size of
all males groups from 2006 to 2008
70%
.Alpine ibex group size is correlated
60%
with population density and has
50%
been used as an estimator of
population size (Toïgo, 1996). The
40%
Marmolada colony experienced a
30%
severe demographic decline, due to
20%
the outbreak of sarcoptic mange in
10%
winter 2003-2004, which also
0%
caused a decrease in group size
1
2-5
6-10
11-20
>20
(Monaco et al., 2005). The
III year
observed tendency toward an
c
Figura 18: Group size experienced by ibexes released on the
increase of the group size could
first (TAR1- grey bar) and the second (TAR2- blue bar)
therefore be an encouraging signal
research year and by local males (in white) during the three
of the growth of the colony. To this
years of research.
purpose, block counts gave an
extimated number of 114 individuals in 2006, 151 in 2007, and 185 in 2008.
b
17
Inter-individual association index between males
Having individually marked animals, it is possible to calculate their individual tendency to
associate with each other. We compared the tendency of TAR1 and TAR2 individuals to
associate within themselves or with local individuals. The tendency of local ibexes to
associate within themselves was used as a reference pattern.
Associations were quantified, for each month, by means of a modified Ginsberg e Young
(1992) association index:
Iab=x/(x+ya+yb)
where:
x=number of sightings in which a and b were together in a given month;
ya= number of sightings of a without b in a given month;
yb= number of sightings of b without a in a given month.
The index varies from 0 (two animals never associate with each other) to 1 (two animals are
always in the same group).
Local males (figure 19 a) were
almost never observed together
with
other
males
from
November to January, around
the rutting season.
The
tendency
to
join
other
individuals increased then
progressively to reach a
maximum in summer-early
autumn (June-October). The
association
index
never
reached, on average, values
higher than 0.4. This indicates
that individual associations,
and hence group composition,
are not stable.
TAR 1 ibexes almost did not
associate with local males
throughout the first summer
after release (figure 19 b), and
started to group together with
them from the following
spring/summer. Afterwards, we
did not observe a preferential
association of TAR1 with
TAR1 as respect to local
ibexes.
Loc al-loc al
0,4
0,3
0,2
0,1
0
6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4
2006
2007
0,4
TAR1-TAR1
2008
2009
TAR1-Local
0,3
0,2
0,1
0
6 7 8 9 10 1112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 1011 12 1 2 3 4
2006
0,6
2007
TAR2
2008
2009
TAr2-Local
0,5
0,4
0,3
0,2
0,1
0
6 7 8 9101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4
Once again TAR2 males
behaved differently than TAR1
(figure 19 c). Although they
tended to associate more within
themselves than with local
18
2006
2007
2008
2009
Figure 19: association indexes of local with local ibxes (a); of TAR1
with TAR1 and with local ibxes (b), and of TAR2 with TAR” and
local ibexes (c).
males during the first year after release, this difference was slight. In addition, they started
joining local males much sooner after release than TARl. This result can explain why we
recorded an higher percentage of TAR2 males in large groups than TAR1 males.
Association index between males and females
In order to obtain an estimate of association tendency between males (both introduced and
local) and females, we used a simplified index computed as follows:
Y= x/(x+n)
where:
x=number of sightings of collared males with females in a given month;
n=number of sightings in which collared males were alone in a given month.
We used the simplified index because the sample of ear-marked females in the population
wassmall and most sightings were of unmarked (and therefore individually unrecognizable)
females. The index varies from 0 (no association) to 1 (always associated). Results are
reported in figure 20.
indice di associazione
The
general
pattern
observed corresponds to
Local
TAR1
TAR2
that usually described for
0,7
the
species
(Bassano,
0,6
2006). Alpine ibex is
0,5
characterized by a strong
0,4
sexual segregation: adult
0,3
males and females occupy
0,2
different habitats and are
0,1
separated for most part of
the
year,
and
they
0
5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3
aggregate in the same herd
-0,1
2006
2007
2008
2009
only during the rutting
year. Mixed groups can still Figure 20 Association indexes of local and translocated males with
be observed after the females
rutting season, when food resources are available in restricted areas. Also in low density
populations, such as recently reintroduced colonies, mixed sex groups can be observed
outside the rutting season (Mustoni et al., 2002), as was also the case for the Marmolada
colony..
During the first year post-release, TAR1 males tended to associate with females less than
local males. The maximum index value was 0.35 (observed in December 2006) in the first
rutting season, while during the same month the value observed for local males was 0.65. In
the second year this difference vanished. TAR2 males associated with females similarly to
local males since their first rutting season in Marmolada.
Comments
Our results on group size experienced and association indexes suggest that social integration
of male ibexes introduced in an established colony is a slow process, that may require one to
two years to be completed. As compared to local males, newly translocated males initially
tended to be more solitary or to associate more among themselves than with local males. This
behaviour was observed particularly in the TAR1 ibexes released in 2006, while the TAR2
integrated faster in the new colony. The pattern of progressive normalisation of social
19
behaviour matches closely the patterns, above described, of progressive stabilisation of spatial
behaviour.
The association of translocated males with local females proceeded faster than that observed
with local males. Only during the first year TAR1 tended to associate less than local males
with females. A high association index indicates that males were not prevented from joining
females, but it doesn’t mean that they have successfully reproduced. During pre-rutting
season males fights to define a hierarchy (based on body and horns size), which regulate the
priority of access to females in the rutting season (Bassano 2006,Willisch e Neuhaus 2008);
only bigger males usually reproduce (Bassano2006, Toïgo et al. 2007).
Observing matings is really difficult in this species, and we did not collect a sufficient number
of observations. In any case, male reproductive success may be assessed with accuracy only
using a genetic approach. Up to now several genetic samples has been collected, and the
genetic analysis will be one of the tasks of the next years of research in Marmolada.
Conclusions and products of the research
Three years after the release of Tarvisio males in the Marmolada massif, we can state that the
restocking was successful. None of the translocated males abandoned the colony, and all
survived showing no capture/transport related stress.
However, their integration into the colony appeared to be a complex process. The released
ibexes needed one or even two years to conclude explorative movements, stabilise spatial
behaviour and fully associate with local males. It is interesting how the subjects released in
the second year adapted faster their spatial and social behaviour than those released in the first
year. We cannot distinguish whether this resulted from a facilitation by ibexes released in the
previous year, or from an individual attitude. In any case, in all spatial and social parametrs
we parameters we observed a very remarkable individual variability, which couldn’t be
explained by age and boy mass differences.
The experience and knowledge gained by monitoring the post release behaviour of ibexes
translocated in Marmolada might be very useful in designing future restocking interventions
aimed at reinforcing small and isolated colonies. This is particularly relevant for the Eastern
Alps, where the distribution of Ibex is still far from that suggested by habitat suitability
evaluations, and is fragmented into colonies often of a very small size. Restocking
programmes have also been suggested as a management tool in the recent discussion of the
possibility of hunting the species in Italy (Tosi G., personal communication).
Obviously, a three-year monitoring of post-release spatial and social behaviour can only
address the short term outcomes of the translocation. This time interval is largely insufficient
to obtain information on the effects the translocations might have exerted on the long term
viability of the colony. To this purpose, we need first to know whether and how the epidemic
and the subsequent crash have affected the genetic variability within the colony, and whether
and how it has been influenced by the translocation. Tissue/blood samples of individuals
perished in the epidemic were already stored at the beginning of the project, and in these three
years we have started collecting samples from survivors and individuals born after the crash
and after the release of Tarvisio ibexes. But more time and samples are needed, and assessing
whether translocated males have reproduced successfully and how they have influenced the
genetic structure of the population is an important task for the next years. Time will also be
20
needed to test the demographic effects of the sarcoptic mange epidemics on the survival of the
colony, and to verify whether it has acquired resistance to this illness.
Therefore, this project was important also because it laid the foundations for a long-term
study on the ecology and demography of the colony. In addition to starting the genetic
databank, we gained a deep knowledge of the spatial behaviour, seasonal distribution and
habitat use of the colony, which will help improving counts and monitoring procedures. In
addition to males, a large proportion of which are now individually marked, we were able to
direct our interest also to females. Presently, 11 females are radiocollared and other 23 are ear
tagged. With an increase in sample size, in the next years we hope to be able to investigate
survival and reproductive success of the population.
Finally, the results obtained in the project have been (and will be) presented in the following
scientific meetings:
1. Rossi L., Menzano A., Sommavilla G.M., De Martin P., Cadamuro A., Rodolfi M.,
Coleselli A. e Ramanzin M. 2006. Actions for the recovery o fan Alpine ibex herd
affected by epidemic scabies: the Marmolada case, Italy. 3rd International Conference
on Alpine ibex, 12-14 October 2006. Pontresina, Switzerland
2. Dal Compare L, Sturaro E., Rossi L, Sommavilla GM, Ramanzin M.. Restocking of
male ibex (Capra ibex): post-release behaviour in the Marmolada colony (Eastern
Italian Alps). II Congreso Internacional del Genero Capra en Europa. 20-23 November
2007, Granada, Spain
3. Scillitani L., Sturaro E., Rossi L., Menzano A. e Ramanzin M.. The Marmolada ibex
project: status of the research and future perspectives. 11-12 Dicember 2008, Ceresole
Reale, Italy
4. Scillitani L., Sturaro E., Rossi L., Menzano A. e Ramanzin M. .Spatial and social
behaviour of adult male Alpine ibex (Capra ibex ibex) after a restocking intervention
in the eastern Italian Alps. 10-14 Novembre 2009, Granada, Spain
They have also produced a chapter (Ramanzin M., Rossi L. and Caldesi L. Fighting the
invisible enemy: an ibex conservation project in the Dolomite Alps, Italy, in press) in a book
being edited by Safari Club International. In the next year they will be summarised in at least
three scientific papers submitted to international journals, and will support a PhD thesis in the
Department of Animal Science at Padova University.
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21
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