The Monito Island Experience

The Monito Island Experience

Department of Natural and Environmental Resources
• M.A. García
• R. López
• F. Nuñez

U.S. Fish and Wildlife Service
•
•
•
•

J.P Zegarra
I. Llerandi-Román
J.A. Cruz-Burgos
O. Monsegur
University of Puerto Rico-Río Piedras
• C. Figuerola
• Puerto Rico Department of Natural Resources and
Environment
• Toledo Zoo (USA)
• U.S. Fish and Wildlife-Caribbean Ecological Services
Field Office
• USA Coast Guard
• University of Puerto Rico
• Island Conservation
• Alberto Álvarez/Carlos Diez
Eddie Ventosa
• Orca Too Crew
Monito Island
16 ha (40ac)
uninhabited
Mona Island
5,519 ha
uninhabited
• Limestone Island completely surrounded by cliffs.
• Inaccessible compared to the rest of the islands of the archipelago.
• Located about 4.7 km (3 miles) northwest of Mona Island and
about 80 km (50 miles) off the western coast of Puerto Rico.
• Covered with xeric scrub vegetation within the Subtropical Dry
Forest Life Zone.
• Endemic Gecko (Sphaerodactylus micropithecus)
• Harrisia portoricensis (endemic columnar cactus
restricted to Mona, Monito and Desecheo)
• Yellow-Shouldered Blackbird (Agelaius xhantomus)
• Important sea bird nesting colonies
• Bobbies (masked, brown, red footed)
• Frigatebirds
Omar Monsegur USFWS
• High Biodiversity of Habitats and Species
• High Percentage of Endemic Species
Raised reef
• High Extinction
Rates
Mangrove islands
Lowland dry limestone
Volcanic & sedimentary
• To provide a summary of the restoration
implemented-a rat eradication program
• To provide a summary of the 15 year posteradication evaluation
• To outline the results and next steps after the
post-eradication evaluation
• First eradication campaign-October 1992-April 1993
Two poisoning episodes:
– Maki mini blocks (Bromadiolone 0.05%)
– Ca. 297 kg rodenticide
– 10 m fixed baiting points (no baiting station)
– 1 rat survey transect (120 m)
– 100 % human resources (no helicopters)
• Project stopped on March 1993 due to a
“Violation” to the Federal Insecticide,
Fungicide and Rodenticide Act (FIFRA)
“Potential poison ingestion by the Monito Island Gecko”
A bioessay was conducted and showed that geckos
were not attracted to poison
First poisoning
Six months later
Project stopped
2nd Eradication Program
• Second eradication campaign-October 1998
Three poisoning episodes:
– Talon G (brodifacoum)
– Ca. 408.6 kg rodenticide
– 20 m fixed baiting stations
– 3 rat survey transects (100 m each one)
– Helicopter and human resources
• Five rat surveys conducted in 1999
• No rats were caught on snap traps
• Low rat presence was detected even before
poisoning
• No rats detected after poisoning
• Interagency effort (PRDNER, USFWS, UPR-RP)
• Conducted by 8 wildlife biologists
• Two nights – 3 days effort
• Rat surveys
• 27 snap traps (20 m apart) = 540 m long transect
• 70 plastic chewing pieces (10 m apart)
• All snap traps and chewing sticks were verified
around 6:30 AM every morning (2 nights).
• All snap traps that were triggered still had bait on them
• Food items were intentionally left out around the
camp area during the night.
• No rats trapped on any trap or chewing stick, no rats
observed around the Island
• All evidence indicates that Monito Island has
been rat free probably since September 1999.
• García et al. 2002-Rat Surveys September 1999,
rats not detected/observed.
• Anderson and Steeves 2000- Bird Surveys, rats not
detected/observed (this was not a rat survey).
• R. López (PRDNER) 2005- visited the Island to
conduct sea bird study and did not see rats.
• Monito Island Gecko
• Marine Birds
• Higo Chumbo- Harrisia cactus
DATE
RESULTS (# geckos)
REFERENCE
24-25 August 1982
18
Dodd and Ortiz 1983
1-2-3 May 1984
4
Hammerson 1984
1988
0
September 1992
4
October 1992
3
February 1993
13
July 1993
0
García (unpublished report)
• Surveys were conducted the first and third
nights of the trip.
• Surveys consisted on actively searching all the
habitats and substrates.
• The majority of the geckos detected were seen
on exposed substrates and not hidden under
rocks or litter.
Date
Number of Monito geckos
detected
Day 1
6-7
Day 2
1
Day 3
23
Type of Habitat
Rocky substrate
Soil substrate
Rocky substrate
Rocky substrate
Rocky substrate
Mixed substrate (leaf litter under a
ficus mixed with rocks)
Total Birds Detected
Masked booby
(Sula dactylatra)
Brown booby
(Sula leucogaster)
Red-footed booby
(Sula sula)
Frigatebird
(Fregata magnificens)
Yellow-shouldered
blackbird
(Agelaius xanthomus)
Total
Age Class
Adult
Juvenile
Fledgling & Hatchling
Adult
Juvenile
Fledgling & Hatchling
Adult
Juvenile
Fledgling & Hatchling
Adult
Juvenile/Hatchling/Fledgling
All classes
Number Birds Detected
430
155
36
430
414
97
290
34
8
79
278
47
2,298
• The island was divided in 3 parcels (Parcel #1 - West,
Parcel #2 - Center, Parcel #3 - East).
• All the parcels were surveyed at the same time
(5pm – 7pm) by 7 biologists.
• All the birds detected perched were included in
the sample.
• Birds that were flying were not included in the
sample. Therefore, we acknowledge marine bird
populations were slightly underestimated during
the survey.
Green dots indicate tagged individuals or clusters of
individuals.
Red polygon: area where the individuals were not
tagged (# individuals was estimated from the nearest
highest point.
• Basically absent in areas with vegetation cover greater than 2 m
and areas occupied by the core of the seabird colony (center of the
island)
• We counted approximately 136 individuals [98 adults and 38
juveniles]. No seedlings were documented
• 58 tagged individuals height and # of branches data for 60
individuals
• The majority (85%) of the tagged individuals taller than 1 m with
an avg. height of 1.6 m (indicating a population structure composed
mostly by mature “old” individuals)
• About 90 % of the tagged individuals with evidence of
undetermined lesions due to fungi or bacteria (higher severity of the
lesions associated to the taller individuals)
• There was not evidence of Harrisia cacti mealybug
• To Conduct Monito Gecko Population Surveys /
Estimates
• To Conduct Marine Birds Population Censuses
• Monito Gecko downlisting to threatened in the
next two years and eventual delisting in 5 years?
• Post-delisting monitoring surveys during the next
5 years