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Evidence that eradicating black rats ( Rattus rattus ) has boosted the

Antiguan Racer Conservation Project, Antigua. Evidence that eradicating black rats ( Rattus rattus ) has boosted the recovery of rare reptiles and seabirds on Antiguan islands. Jenny C. Daltry Fauna & Flora International Karron J. James , Andrea Otto , and Toby N. Ross

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Evidence that eradicating black rats ( Rattus rattus ) has boosted the

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  1. Antiguan Racer Conservation Project, Antigua Evidence that eradicating black rats (Rattus rattus) has boosted the recovery of rare reptiles and seabirds on Antiguan islands. Jenny C. Daltry Fauna & Flora International Karron J. James, Andrea Otto, and Toby N. Ross Environmental Awareness Group

  2. Antiguan Racer Conservation Project, Antigua Study area: The Offshore Islands of Antigua

  3. Antiguan Racer Conservation Project, Antigua • More than 30 islands • Range from <0.1 to 184 hectares. Study area: The Offshore Islands of Antigua

  4. Antiguan Racer Conservation Project, Antigua • More than 30 islands • Range from <0.1 to 184 hectares. • Mix of private and state-owned • Nearly all colonised by Black Rats (Rattus rattus) Study area: The Offshore Islands of Antigua

  5. Antiguan Racer Conservation Project, Antigua Black or Ship Rat (Rattusrattus) Omnivorous Native to India/Central Asia

  6. Antiguan Racer Conservation Project, Antigua Antiguan Racer (Alsophisantiguae) Critically Endangered Endemic to Antigua

  7. Antiguan Racer Conservation Project, Antigua • Vanished from mainland Antigua after Asian mongooses were introduced (1890s). • By 1980s, the snakes were only on Great Bird Island (8.4 hectares) Great Bird Is. Antiguan Racer (Alsophisantiguae) Critically Endangered Endemic to Antigua

  8. Antiguan Racer Conservation Project, Antigua Great Bird Island Mark-recapture study in 1995 found 50 ± 7 individuals. More than 50% of the snakes had injuries consistent with rat bites.

  9. Antiguan Racer Conservation Project, Antigua Methods: • Cut grid (10x10m or 20x20m) across each island (4-6 weeks). • Placed brodifacoum briquettes (KleratTM) on grid intersections (3 weeks). Rat eradication programme began in 1995. Forestry staff and NGO volunteers eradicated rats from Great Bird Island and neighbouring islands.

  10. Antiguan Racer Conservation Project, Antigua Methods: • Cut grid (10x10m or 20x20m) across each island (4-6 weeks). • Placed brodifacoum briquettes (KleratTM) on grid intersections (3 weeks). • 100% effective on every island. Rat eradication programme began in 1995. Forestry staff and NGO volunteers eradicated rats from Great Bird Island and neighbouring islands.

  11. Antiguan Racer Conservation Project, Antigua x x Black Rats were eradicated from 12 islands between 1995 and 2006. (Two islands were re-invaded by rats).

  12. Antiguan Racer Conservation Project, Antigua Methods: • Use commercial bait stations for rats. • Stations raised off ground to exclude crabs. • Contain KleratTM 0.005% brodifacoum • 80 stations, checked every 5-6 weeks. Permanent bait stations in use since 2001. Designed to detect and kill invading rats.

  13. Antiguan Racer Conservation Project, Antigua Methods: • Standard mark-recapture study every 1-2 years. • Snakes marked using PIT tags. • Use Begon’s (1979) Weighted Mean estimator. Antiguan Racer population more than doubled within two years of eradicating rats from Great Bird Island.

  14. Antiguan Racer Conservation Project, Antigua • Rabbit Island (1999) • Green Island (2002) • York Island (2008) • All three colonies are breeding well. Great Bird Is. Rabbit Green Is. York Is. Antiguan Racers have been re-introduced from Great Bird Island to 3 islands (after eradicating rats).

  15. Antiguan Racer Conservation Project, Antigua 10 x incease in snake population since rat eradication programme began.

  16. Antiguan Racer Conservation Project, Antigua Seabirds and pigeon colonies have been monitored by the authors and local volunteers.

  17. Antiguan Racer Conservation Project, Antigua Breeding pairs of birds on Great Bird Island and the Galley Islands Massive increase in seabird and pigeon colonies after eradicating rats.

  18. Antiguan Racer Conservation Project, Antigua Breeding pairs of birds on Rabbit, Redhead and Lobster Islands Massive increase in seabird and pigeon colonies after eradicating rats.

  19. Antiguan Racer Conservation Project, Antigua • Antigua’s offshore islands were designated an Important Bird Area in 2009. • The seabird colonies are becoming a tourist attraction. Could these increases be due to factors other than removing rats?

  20. Antiguan Racer Conservation Project, Antigua • Seabird survey conducted in June 2010: • 6 islands with rats present. • 9 islands cleared of rats by OICP • 9 very small islets never known to have rats. • Standardized methods used for every species. A rapid survey was conducted in 2010 to compare islands with and without rats.

  21. Antiguan Racer Conservation Project, Antigua Breeding pairs of seabirds on offshore islands, June 2010 RATS PRESENT NEVER HAD RATS? RATS REMOVED 1998 1995 1998 1998 1998 1995 1995 2006 2001 No breeding seabirds were found on the rat-infested islands.

  22. Antiguan Racer Conservation Project, Antigua • Other bird species • Marine turtles • Lizards • Land snails Anecdotal evidence that other species are more abundant on rat-free islands. More research needed.

  23. Antiguan Racer Conservation Project, Antigua • Direct predation of eggs, young, even adults. • Depletion of prey/ food sources. • Gross changes to habitats. How do rats affect animal populations?

  24. Antiguan Racer Conservation Project, Antigua Great Bird Island 1995 – Just before rats were eradicated Great Bird Island 2005 – After 10 years without rats. Birds

  25. Antiguan Racer Conservation Project, Antigua Some Lessons Learned: 1. Black rats do have seriously harmful impacts on Antiguan biodiversity. 2. Rats can be controlled, even in public areas, and the recovery of native species can be very rapid. 3. Ideally, monitoring of flora and fauna should begin before rats are eradicated.

  26. 4. Restoring islands also has a powerful social impact: This project has motivated many people from diverse backgrounds to become conservationists.

  27. Antiguan Racer Conservation Project, Antigua Acknowledgements Project Partners Forestry Unit, Ministry of Agriculture Environmental Awareness Group (EAG) Fauna & Flora International (FFI) Island Resources Foundation Durrell Wildlife Conservation Trust Black Hills State University Co-sponsors Disney Worldwide Conservation Fund Mohammen bin Zayed Conservation Fund Syngenta (donate KleratTM) USFWS – Critically Endangered Animals Conservation Fund USFWS – Neotropical Migratory Birds Conservation Act

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