Palatability and efficacy of rodent baits for eradicating house mice (Mus musculus) from Gough Island, Tristan da Cunha
R. J. Cuthbert A C , P. Visser A , H. Louw A and P. G. Ryan BA Royal Society for the Protection of Birds, The Lodge, Sandy, Bedfordshire, SG19 2DL, United Kingdom.
B DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, University of Cape Town, Rondebosch 7701, South Africa.
C Corresponding author. Email: richard.cuthbert@rspb.org.uk
Wildlife Research 38(3) 196-203 https://doi.org/10.1071/WR11016
Submitted: 25 January 2011 Accepted: 21 March 2011 Published: 13 July 2011
Abstract
Context: Introduced house mice (Mus musculus) are a serious predator of seabird chicks at Gough Island, resulting in declining populations of several threatened species. This has prompted the preparation of plans to eradicate mice from Gough and other islands. However, relatively little is known about the palatability and efficacy of rodent baits for house mice, as most studies have focussed on rats (Rattus spp.).
Aims: The study’s aim was to test the palatability of non-toxic forms of two commercially available rodent pellet bait formulations (Pestoff® 20R and Final®) and a new pellet bait formulated specifically for mouse control (Pestoff® 20M) to house mice on Gough Island. We also tested the efficacy of toxic Pestoff 20R and Final pellets containing 20 and 25 ppm of the anticoagulant toxin brodifacoum.
Methods: Five trials with 50 mice housed in individual cages and kept at ambient temperature and light cycles, were undertaken during the year. Palatability of bait pellets was measured over five days and compared with a non-toxic control food (standard ‘rodent pellets’ sourced from a pet food supplier). Toxic bait trials were run for 25 days with bait administered at 1, 2 and 10 g for a 24-h period and at 20 g per day for 72 h.
Key results: All three baits were highly palatable; however, mice showed the greatest preference for Pestoff 20M and 20R, consuming a larger mass of bait. Estimated oral LD50 values of brodifacoum for Gough mice were 0.44 mg kg–1 and the average time to death following exposure was 5.5 days (range 0–16 days). Two mice (~1% of those tested) survived after apparently ingesting doses of brodifacoum estimated to be 5 and 10 times the oral LD50 values, potentially indicating a lower susceptibility to brodifacoum in some individuals, although subsequent exposure at higher doses resulted in mortality.
Conclusions: The results of this study confirmed that house mice on Gough Island find bait pellets highly palatable and that brodifacoum is an effective toxin with LD50 values and time to death within the same range (0.4 to 0.52 mg kg–1 and 5.2 days) as other studies, indicating no major difference in the susceptibility of Gough mice to this poison.
Implications: We recommend that bait manufacturers produce formulations designed to be attractive to mice and consider the use of higher concentrations of brodifacoum to increase the likelihood of all mice obtaining a toxic dose when small quantities of bait are consumed, although higher toxin concentrations must be balanced against the increased risks to non-target species. Eradication operations targeting mice should undertake more than one bait drop to ensure any individuals surviving the initial drop have access to sufficient toxic bait to cause mortality upon second or subsequent exposure.
References
Angel, A., and Cooper, J. (2006). ‘A Review of the Impacts of Introduced Rodents on the Islands of Tristan da Cunha and Gough.’ (Royal Society for the Protection of Birds: Cape Town.)Billing, J. (2000). The control of introduced Rattus rattus L. on Lord Howe Island. II. The status of warfarin resistance in rats and mice. Wildlife Research 27, 659–661.
| The control of introduced Rattus rattus L. on Lord Howe Island. II. The status of warfarin resistance in rats and mice.Crossref | GoogleScholarGoogle Scholar |
Clapperton B. K. 2006
Cleghorn, M., and Griffiths, R. (2002). ‘Palatability and Efficacy of Pestoff 20R Bait on Mice from Mokoia Island, Roturua.’ DOC Science Internal Series 25. (Department of Conservation: Wellington, New Zealand.)
Cuthbert, R., and Hilton, G. (2004). Introduced house mice Mus musculus: a significant predator of endangered and endemic birds on Gough Island, South Atlantic Ocean? Biological Conservation 117, 483–489.
| Introduced house mice Mus musculus: a significant predator of endangered and endemic birds on Gough Island, South Atlantic Ocean?Crossref | GoogleScholarGoogle Scholar |
Cuthbert, R., Sommer, E., Ryan, P. G., Cooper, J., and Hilton, G. (2004). Demography and conservation of the Tristan albatross Diomedea (exulans) dabbenena. Biological Conservation 117, 471–481.
| Demography and conservation of the Tristan albatross Diomedea (exulans) dabbenena.Crossref | GoogleScholarGoogle Scholar |
Cuthbert, R. J., Visser, P., Louw, H., Rexer-Huber, K., Parker, G., and Ryan, P. G. (2011). Preparations for the eradication of mice from Gough Island: results of bait acceptance trials above ground and around cave systems. In ‘Island Invasives: Eradication and Management’. (Eds C. R. Veitch, M. N. Clout and D. R. Towns.) (IUCN: Gland, Switzerland.) In press.
Eason, C. T. (1996). An evaluation of difference rodenticides for use on Lord Howe Island. Landcare Research Contract Report LC9596/102, Lincoln, New Zealand.
Fisher, P. (2005). ‘Review of House Mouse Susceptibility to Anticoagulant Poisons.’ DOC Science Internal Series 198. (New Zealand Department of Conservation: Wellington, New Zealand.)
Godfrey, M. E. R. (1985). Non-target and secondary poisoning hazards of ‘second generation’ anticoagulants. Acta Zoologica Fennica 173, 209–212.
Griffiths, R., and Towns, D. (2008). ‘Rangitoto/Motutapu Pest Eradication Feasibility Study.’ (Department of Conservation: New Zealand), unpublished report.
Hayes, J. P., and Shonkwiler, J. S. (2001). Morphological indicators of body condition: useful or wishful thinking? In ‘Body Composition Analysis of Animals: A Handbook of Non-destructive Methods’. (Ed. J. R. Speakman.) pp. 1–8. (Cambridge University Press: Cambridge.)
Howald, G., Donlan, C. J., Galvan, J. P., Russell, J. C., Parkes, J., Samaniego, A., Wang, Y., Veitch, D., Genovesi, P., Pascal, M., Saunders, A., and Tershy, B. (2007). Invasive rodent eradication on islands. Conservation Biology 21, 1258–1268.
| Invasive rodent eradication on islands.Crossref | GoogleScholarGoogle Scholar | 17883491PubMed |
Jacobs, W. (1994). Pesticides federally registered for control of terrestrial vertebrate pests. In ‘Prevention and Control of Wildlife Damage’. (Eds S. Hygnstrom, R. Timm and G. Larson.) pp. G1–G22. (University of Nebraska, Cooperative Extension Service: Lincoln, NE.)
MacKay, J. W. B., Russell, J. C., and Murphy, E. C. (2007). Eradicating house mice from islands: successes, failures and the way forward. In ‘Managing Vertebrate Invasive Species: Proceedings of an International Symposium’. (Eds G. M. Witmer, W. C. Pitt and K. A. Fagerstone.) pp. 294–304. (USDA/APHIS/WS, National Wildlife Research Center: Fort Collins, CO.)
Moors, P. J., and Atkinson, I. A. E. (1984). Predation on seabirds by introduced animals, and factors affecting its severity. ICBP Technical Publication No 2, 667–690.
Morris, G. A. (2007). Suceptibility of Rangitoto and Motutapu island house mice to 20R brodifacoum baits. Landcare Research Contract Report LC0607/155. (Landcare: Lincoln, New Zealand.)
Morris G. A. O’Connor C. E. Airey A. T. Fisher P. 2008
O’Connor, C. E., and Booth, L. H. (2001). Palatability of rodent baits to wild house mice. In ‘Science for Conservation’. Vol. 184. (Department of Conservation: Wellington, New Zealand.)
Parkes, J. (2008). A Feasibility Study for the Eradication of House Mice from Gough Island. RSPB Research Report No. 34. (Royal Society for the Protection of Birds: Sandy, Bedfordshire, UK.)
Thomas, M. D. (2008). ‘Palatability of a New Mouse Bait Manufactured by Animal Control Products Ltd.’ (Pest Control Research Research: Wanganui, New Zealand.)
Torr, N. (2002). Eradication of rabbits and mice from subantarctic Enderby and Rose islands. In ‘Turning the Tide: The Eradication of Invasive Species’. (Eds C. R. Veitch and M. N. Clout.) pp. 319–328. (IUCN SSS Invasive Species Specialist Group: Gland, Switzerland.)
Wanless, R. M., Angel, A., Cuthbert, R. J., Hilton, G. M., and Ryan, P. G. (2007). Can predation by invasive mice drive seabird extinctions? Biology Letters 3, 241–244.
| Can predation by invasive mice drive seabird extinctions?Crossref | GoogleScholarGoogle Scholar | 17412667PubMed |
Wessa, P. (2008). Multiple Regression (v1.0.26) in Free Statistics Software (v1.1.23-r4), Office for Research Development and Education, URL. Available at http://www.wessa.net/rwasp_multipleregression.wasp/ (Accessed 12 December 2009).
Witmer, G. (2007). ‘Efficacy of Commercially Available Rodenticide Baits for the Control of Wild House Mice.’ Unpublished final report, No. QA-1304. (USDA/APHIS/WS-National Wildlife Research Center: Fort Collins, CO.)
