issg Database: Management and Information Links for Cricetomys gambianus

Cricetomys gambianus (mammal)

Ecology Distribution Management
Info Impact
Info References
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         Management Information

Preventative measures: In 2007 Cricetomys gambianus was added to the list of Prohibited Species in Florida based on risks to Florida agriculture, native rodent species and human health (Hardin, 2007).
Potential sites for transfer of the rats to the mainland, such as transfer stations and highways, should be monitored to prevent or limit dispersal to new sites (Engeman et al., 2006).
Development of methods to detect and survey Gambian pouched rats is essential for measuring distribution and abundance, detecting incursions and assessing the effectiveness of control methods. Motion-triggered digital cameras with a lure of mineral oil and peanut butter provide an effective monitoring method, but cost and theft/vandalism are limiting factors. Tracking methods, which are more cost effective but more labour intensive provide a useful complement to cameras in areas where theft may be a problem (Engeman et al. 2006).
Chemical: Based on initial toxicant bait testing the two most effective baits were: the first generation anticoagulant, 0.005% diphacinone (Ramik minibars) and the acute 2% zinc phosphide bait (mixed with peanut butter and horse sweet mix). The Ramik bait needs to be consumed several times to be effective, whereas a small amount of the acute zinc phosphide bait is lethal (Engeman et al., 2006). Delivery of bait via bait stations made from PVC pipe ensure that native species are excluded (Engeman et al. 2006). Recommendations include prebaiting for three days to help prevent ‘bait-shyness and bait station spacing at grids of no more than 50x50 m spacing (Engeman et al., 2006).
A pilot eradication was conducted on Crawl Key before attempting eradication on larger, heavier infested Grassy Key. A 40x40 m grid of bait stations was established using zinc phosphide bait. Preliminary camera surveys found no evidence of rats remaining, although further monitoring required to confirm eradication success (Engeman et al., 2007).
A similar effort was carried out on Grassy Key between May-June 2007. Zinc phosphide bait was used placed at 40x40 m grid in known areas with rats, and 50x50 m grid in all other areas, giving a total of 1000 bait stations. However this eradication was unsuccessful with rats detected soon after baiting (Engeman et al., 2007). The lack of success was attributed to several factors: not all landowners would allow baiting on their properties which may have provided refuge from bait (Engeman et al., 2007), use of bait stations which may have excluded some rats, or bait shyness (Witmer et al., 2010b).As the eradication on Grassy Key was unsuccessful there has been further research into evaluating different rodenticide baits and attractants. Zinc phosphide and brodifacoum were found to be the most effective poisons (Witmer et al., 2010b). The most effective attractant for detection and eradication of Gambian pouched rats from those tested was a blend of faeces and urine from conspecifics. Use of faeces and urine in combination with a second attractant such as peanut butter, anise extract, ginger or FAS (fatty acid) extract may be even more successful. Further testing should help to identify additional and potentially better attractants for Gambian rats (Witmer et al. 2010a).
Physical:Trapping has been used on Grassy Key, Florida for detection and removal, providing information on distribution and evaluating trapping techniques and impacts. While Gambian pouched rats are easily trapped using, large numbers of non-target species are captured, reducing the effectiveness of trapping (Engeman et al., 2007).
Trapping as an eradication method should probably only be used if Gambian pouched rats were discovered on keys within the range of endangered rodents, such as the Key Largo woodrat (Neotoma floridana smalli, as live traps allow safe release of non-target species (Engeman et al., 2006).

         Location Specific Management Information
Crawl Key (Florida Keys)
A pilot eradication was conducted on Crawl Key before attempting eradication on the larger, heavier infested Grassy Key. A 40x40 m grid of bait stations was established on Crawl Key using zinc phosphide bait. Preliminary camera surveys found no evidence of rats remaining, although further monitoring required to confirm eradication success (Engeman et al., 2007).
Florida (USA)
In 2007 Cricetomys gambianus was added to the list of Prohibited Species in Florida based on risks to Florida agriculture, native rodent species and human health. Thus they may only be possessed by accredited public exhibitors or by research institutions with an approved research plan (Hardin, 2007).
Grassy Key (Florida Keys)
An eradication attempt was carried out on Grassy Key between May-June 2007. Zinc phosphide bait was used placed at 40x40 m grid in known areas with rats, and 50x50 m grid in all other areas, giving a total of 1000 bait stations. However this eradication was unsuccessful with rats detected soon after baiting (Engeman et al., 2007). The lack of success was attributed to several factors: not all landowners would allow baiting on their properties which may have provided refuge from bait (Engeman et al., 2007), use of bait stations which may have excluded some Gambian pouched rats, or bait shyness (Witmer et al., 2010). An intensive 2-week trapping and remote camera session in June 2010 revealed no rats so the invasive species may have been eradicated from Grassy Key (G. Witmer, pers. comm.). Additional monitoring is planned to assure a successful outcome.

         Management Resources/Links

1. Christina L. Hutson, Kemba N. Lee, Jason Abel, Darin S. Carroll, Joel M. Montgomery, Victoria A. Olson, Yu Li, Whitni Davidson, Christine Hughes, Michael Dillon, Paul Spurlock, James J. Kazmierczak, Connie Austin, Lori Miser, Faye E. Sorhage, James Howell, Jeffrey P. Davis, Mary G. Reynolds, Zachary Braden, Kevin L. Karem, Inger K. Damon, and Russell L. Regnery, 2007. Monkeypox zoonotic associations: insights from laboratory evaluation of animals associated with the multi-state US outbreak. Am. J. Trop. Med. Hyg., 76(4), 2007, pp. 757–767
2. Engeman, Richard M., Gary W.Witmer, and Jean B. Bourassa, John W.Woolard, Bernice Constantin, and Parker T. Hall, Scott Hardin, Neil D. Perry, 2007. The path to eradication of the Gambian pouched rat in Florida. In Managing Vertebrate Invasive Species: Proceedings of an International Symposium (G. W. Witmer, W. C. Pitt, K. A. Fagerstone, Eds). USDA/APHIS/WS, National Wildlife Research Center, Fort Collins, CO. 2007.
        Summary: Available from: http://etmd.nal.usda.gov/bitstream/10113/17526/1/IND44083364.pdf [Accessed 5 August 2010]
3. Engeman, Richard; Woolard, John W.; Perry, Neil D.; Witmer, Gary; Hardin, Scott; Brashears, Lawrence; Smith, Henry; Muiznieks, Britta; Constantin, Bernice, 2006. Rapid assessment for a new invasive species threat: the case of the Gambian giant pouched rat in Florida. Wildlife Research. 33(6). 2006. 439-448.
4. Higgins, Alison; Serbesoff-King, Kristina; King, Matthew; O'Reilly-Doyle, Kathy, 2007. The power of partnerships: Landscape scale conservation through public/private collaboration. Natural Areas Journal. 27(3). JUL 2007. 236-250.
5. Jenkins, Peter, 2007. The failed regulatory system for animal imports into the United States and how to fix it. In USDA National Wildlife Research Center Symposia Managing Vertebrate Invasive Species
        Summary: Available from: http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1018&context=nwrcinvasive [Accessed 5 August 2010]
6. Perry, Neil D.; Hanson, Britta; Hobgood, Winston; Lopez, Roel L.; Okraska, Craig R.; Karem, Kevin; Damon, Inger K.; Carroll, Darin S., 2006. New invasive species in Southern Florida: Gambian rat (Cricetomys gambianus) Journal of Mammalogy. 87(2). APR 2006. 262-264.
7. Scott Hardin, 2007. Managing non-native wildlife in Florida: State perspective, policy and practice. In USDA National Wildlife Research Center Symposia Managing Vertebrate Invasive Species
        Summary: Available from: http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1013&context=nwrcinvasive [Accessed 5 August 2010]
8. Smith, K. F., K. Acevedo-Whitehouse & A. B. Pedersen, 2009. The role of infectious diseases in biological conservation. Animal Conservation, Volume 12, Issue 1 (p 1-12)
9. Witmer, Gary W.; Snow, Nathan P.; Burke, Patrick W., 2010a. Potential attractants for detecting and removing invading Gambian giant pouched rats (Cricetomys gambianus). Pest Management Science. 66(4). APR 2010. 412-416.
10. Witmer, Gary W.; Snow, Nathan P.; Burke, Patrick W., 2010b. Evaluating commercially available rodenticide baits for invasive Gambian giant pouched rats (Cricetomys gambianus). Crop Protection Volume 29, Issue 9, September 2010, Pages 1011-1014
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The Global Invasive Species Database is managed by the Invasive Species Specialist Group (ISSG) of the IUCN Species Survival Commission. It was developed as part of the global initiative on invasive species led by the Global Invasive Species Programme (GISP) and is supported through partnerships with the National Biological Information Infrastructure, Manaaki Whenua-Landcare Research and the University of Auckland. Conditions of use.