Rat Control
Rats are among the most successful invasive species on the planet. Cayman’s tropical climate provides excellent conditions for rodents in the wild so consistent rodent management with a focus on prevention is essential throughout the year to keep populations under control.
DoE research scientists started placing rat traps in remote forests during cat and iguana surveys and from 2022 to 2024 we saw some fluctuations in the number of rats but overall there wasn’t a notable change compared to 2022 baseline levels.
It’s common for rodent populations to spike and then fall back in response to the seasonal availability of food and water. Rat populations fluctuate between the rainy season (October to December) when rats breed more rapidly in response to the increased water and wild food availability, and the dry season when resources diminish.
And while cats do hunt rats in addition to birds, small reptiles and insects, global research shows the impact cats have on a rat colony’s overall population is minimal because there are easier things to hunt – and our rat and feral cat surveys confirm this. The DoE recently conducted a rat population study before and after feral cat control in Little Cayman. We found no significant change in the rat population after the feral cat population was reduced. What we did see what that the population increased in the rainy summer and a decreased in the dry season confirming other findings that rodent populations fluctuate in response to seasonality in the environment, not to the presence or absence of cats.
So what’s really impacting our rat populations? The number one factor is household waste. Unmanaged garbage and illegal dumping provide rats with perfect conditions to live and breed.
We recommend contacting DEH or a pest control service for rodent control including advice on reducing the presence of rats on your property.
The Department of Environmental Health (DEH) offers rodent control services (baiting) to all public buildings and property owners of private homes.
Contact DEH on 345-949-6696 (Grand Cayman) or 345-948-2321 (Sister Islands) or email: dehcustomerservice@gov.ky to discuss an environmental health assessment of your property.
Learn more about DEH Sanitation Surveillance Services
Download the DEH Rat Guidelines
_______________________________
Please be careful and responsible if you decide at your own risk, to tackle rodent control yourself. Many rat poisons are toxic to humans, pets and wildlife, and snap traps have powerful springs which cause injury.
_______________________________
All rodent control devices including baits and snap traps must always be secured in bait boxes to prevent harm to pets and native wildlife.
Snap Traps
Snap traps baited with peanut butter are very effective and safest if placed inside bait boxes to prevent non-target species from contact.
Rat Bait
Always use securely closed bait boxes to help reduce impacts to non-target species like crabs or birds and be sure to inspect daily.
References:
EPA-738-F-98-003. (1998). EPA R.E.D. Facts. U.S. Environmental Protection Agency | US EPA. https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_PC-088601_1-Jul-98.pdf
ERICSSON, R. J. (1982). ALPHA-CHLOROHYDRIN (EPIBLOC®): A TOXICANT-STERILANT AS AN ALTERNATIVE IN RODENT CONTROL. Gametrtcs Ltd., 180 Harbor Drive, Sausallto, Caltfomta 94965. https://escholarship.org/content/qt7g12w7hq/qt7g12w7hq_noSplash_0cc34c7f076b7e473320f4442a463857.pdf?t=q58hvf
Fagerstone, K. A., M. A. Coffey, P. D. Curtis, R. A. Dolbeer, G. J. Killian, L. A. Miller, and L. M. Wilmot. 2002. Wildlife fertility control. Wildl. Soc. Tech. Rev. 02-2, 29 pp.
Gupta, R. C. (2018). Zinc Phosphide. Science Direct. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/zinc-phosphide
Hommerding, H. (2022). Alpha-Chloralose Poisoning in Animals – Alpha-Chloralose Poisoning in Animals – MSD Veterinary Manual. MSD Veterinary Manual. https://www.msdvetmanual.com/toxicology/rodenticide-poisoning/alpha-chloralose-poisoning-in-animals
Hommerding, H. (2022b). Alpha-Chloralose Poisoning in Animals – Alpha-Chloralose Poisoning in Animals – MSD Veterinary Manual. MSD Veterinary Manual. https://www.msdvetmanual.com/toxicology/rodenticide-poisoning/alpha-chloralose-poisoning-in-animals
Hommerding, H. (2022c). Bromethalin Poisoning in Animals – Bromethalin Poisoning in Animals – Merck Veterinary Manual. Merck Veterinary Manual. https://www.merckvetmanual.com/toxicology/rodenticide-poisoning/bromethalin-poisoning-in-animals
Issa, M.Y., Nasser, W.S., Mikhail, M.W. et al. Comparative Rodenticide Activity of Three Agro Waste Materials in Combat of Rattus norvegicus Under Laboratory Conditions. Proc. Natl. Acad. Sci., India, Sect. B Biol. Sci. 91, 855–863 (2021). https://doi.org/10.1007/s40011-021-01271-w
Noh, A.A.M., Ahmad, A.H. & Salim, H. Efficacy of cholecalciferol rodenticide to control wood rat, Rattus tiomanicus and its secondary poisoning impact towards barn owl, Tyto javanica javanica. Sci Rep 13, 2854 (2023). https://doi.org/10.1038/s41598-023-29499-8
Plumlee, K. H. (2004). Science Direct. Pharmacology, Toxicology and Pharmaceutical Science. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/sulfaquinoxaline#:~:text=Sulfaquinoxaline%20is%20used%20as%20an,exhibit%20a%20broader%20antibacterial%20spectrum.
PPDB, P. P. D. B. (n.d.). Alpha-chlorohydrin (Ref: U 5897). AERU. https://sitem.herts.ac.uk/aeru/ppdb/en/Reports/1231.htm
Saravanan K, Kanakasabai R. Evaluation of secondary poisoning of difethialone, a new second-generation anticoagulant rodenticide to barn owl, Tyto alba Hartert under captivity. Indian J Exp Biol. 2004 Oct;42(10):1013-6. PMID: 15511007.
Saravanan K, Kanakasabai R, Thiyagesan K. Field evaluation of difethialone, a new second generation anticoagulant rodenticide in the rice fields. Indian J Exp Biol. 2003 Jun;41(6):655-8. PMID: 15266918.
Schlatter, J., Baar, A., DiNov, M., Lawrie, S., & Lorentzen, R. (1999). 3-CHLORO-1,2-PROPANEDIOL (JECFA Food Additives Series 48). INCHEM. https://www.inchem.org/documents/jecfa/jecmono/v48je18.htm
Sheri Ann Hild, Jerry R. Reel, Janice M. Larner, Richard P. Blye, Disruption of Spermatogenesis and Sertoli Cell Structure and Function by the Indenopyridine CDB-4022 in Rats, Biology of Reproduction, Volume 65, Issue 6, 1 December 2001, Pages 1771–1779, https://doi.org/10.1095/biolreprod65.6.1771
SPCA. (2024). Rodenticide restrictions made permanent in B.C. starting today. BC SPCA. https://spca.bc.ca/ways-to-help/take-action/urban-wildlife/humane-rodent-control/rodenticides/#:~:text=Rodent%20poisons%20or%20rodenticides%20come,(e.g.,%20brodifacoum,%20bromadiolone,
Suter, K.E. (1984). Effects of an Indenopyridine Derivative, Compound 20–438, on Spermatogonial Stem Cells of the Rat. In: Chambers, P.L., Preziosi, P., Chambers, C.M. (eds) Disease, Metabolism and Reproduction in the Toxic Response to Drugs and Other Chemicals. Archives of Toxicology, vol 7. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-69132-4_24
Trujillo, W. A. (1980). Determination of Warfarin and Sulfaquinoxaline in Rodenticide Concentrates by HPLC. Journal of Liquid Chromatography, 3(8), 1219–1226. https://doi.org/10.1080/01483918008064753
Urbano VR, Maniero MG, Guimarães JR, Del Valle LJ, Pérez-Moya M. Sulfaquinoxaline Oxidation and Toxicity Reduction by Photo-Fenton Process. Int J Environ Res Public Health. 2021 Jan 23;18(3):1005. doi: 10.3390/ijerph18031005. PMID: 33498745; PMCID: PMC7908259.
US EPA. (2006). EPA Pesticide Fact Sheet. U.S. Environmental Protection Agency | US EPA. https://www3.epa.gov/pesticides/chem_search/reg_actions/registration/fs_PC-117101_01-Dec-06.pdf
Wallace, D. (2020). Sodium Fluoroacetate, Handbook of Toxicology of Chemical Warfare Agents (Third Edition). Science Direct. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/sodium-fluoroacetate
Zhelev, G., M. Lyutskanov, V. Petrov, G. Mihaylov, P. Marutsov, K. Koev & Ts. Tsvetanov, 2013. Efficacy of a cellulose-based rodenticide for control of warfarin-resistant black rats (Rattus rattus). Bulg. J. Vet. Med., 16, Suppl. 1, 134–140