The Monito Island Experience

Transcription

1 The Monito Island Experience

2 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

3 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

4 Monito Island 16 ha (40ac) uninhabited Mona Island 5,519 ha uninhabited

5 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.

6 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

7 High Biodiversity of Habitats and Species High Percentage of Endemic Species High Extinction Raised reef Rates Lowland dry limestone Mangrove islands Volcanic & sedimentary

8 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

9 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)

10 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

11 First poisoning Project stopped Six months later

12 2 nd Eradication Program Second eradication campaign-october 1998 Three poisoning episodes: Talon G (brodifacoum) Ca kg rodenticide 20 m fixed baiting stations 3 rat survey transects (100 m each one) Helicopter and human resources

13 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

14 Interagency effort (PRDNER, USFWS, UPR-RP) Conducted by 8 wildlife biologists Two nights 3 days effort

15 Rat surveys 27 snap traps (20 m apart) = 540 m long transect 70 plastic chewing pieces (10 m apart)

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17 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

18 All evidence indicates that Monito Island has been rat free probably since September García et al Rat Surveys September 1999, rats not detected/observed. Anderson and Steeves Bird Surveys, rats not detected/observed (this was not a rat survey). R. López (PRDNER) visited the Island to conduct sea bird study and did not see rats.

19 Monito Island Gecko Marine Birds Higo Chumbo- Harrisia cactus

20 DATE RESULTS (# geckos) REFERENCE August Dodd and Ortiz May Hammerson September October García (unpublished report) February July

21 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.

22 Date Number of Monito geckos Type of Habitat detected Day Rocky substrate Soil substrate Rocky substrate Day 2 1 Rocky substrate Day 3 23 Rocky substrate Mixed substrate (leaf litter under a ficus mixed with rocks)

23 Total Birds Detected Age Class Number Birds Detected Adult 430 Masked booby Juvenile 155 (Sula dactylatra) Fledgling & Hatchling 36 Brown booby (Sula leucogaster) Red-footed booby (Sula sula) Adult 430 Juvenile 414 Fledgling & Hatchling 97 Adult 290 Juvenile 34 Fledgling & Hatchling 8 Adult 79 Juvenile/Hatchling/Fledgling 278 All classes 47 Frigatebird (Fregata magnificens) Yellow-shouldered blackbird (Agelaius xanthomus) Total 2,298

24 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.

25 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.

26 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

27 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

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30 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

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