Witmer, Gary

Dr. Gary Witmer

Dr. Gary Witmer has been a Research Wildlife Biologist with NWRC since 1991. In the past, he worked on a wide array of wildlife species causing damage to forestry and agriculture. In recent years, however, he has focused heavily on rodent population and damage management, including both native and invasive rodent species. He has been involved in designing invasive rodent eradication strategies for islands, several of which have been successfully implemented in the Caribbean and Pacific regions.

NWRC Research Project: Development of Methods to Control Rodent Populations and Damage with an Emphasis on Invasive House Mice and Native Voles

Current Research
Rat toxicants
Mouse toxicants
Rodent barriers
Rat behavior
Gambian giant pouched rat toxicants
Gambian giant pouched rat attractants
Native rodent damage management
Education
Ph.D., Oregon State University, Wildlife Management, Forestry, Statistics
M.S., Purdue University, Wildlife Ecology
M.S., University of Michigan, General Biology
B.S., University of Michigan, General Biology
International Experience
Kenya (rodent management)
Costa Rica (carnivore predation)
Azores (rodent management)
Russia (forest wildlife damage management)
Cuba (rodent and invasive species management)
Australia and New Zealand (invasive rodent management)

Contact Information
  • Address: USDA/APHIS/Wildlife Services, NWRC, 4101 LaPorte Ave., Fort Collins, CO, 80521
  • Telephone: 970-266-6335
  • E-mail: Gary.W.Witmer@aphis.usda.gov

Recent Publications:

2017

Baldwin, R.A., R. Meinerz, and G.W. Witmer. 2017. Novel and current rodenticides for pocket gopher Thomomys spp. management in vineyards: what works?  Pest Management Science 73:118-122.  doi: 10.1002/ps.4307
               

Witmer, G.W., R.A. Baldwin, and R.S. Moulton. 2017. Identifying possible alternative rodenticide baits to replace strychnine baits for pocket gophers in California. Crop Protection 92:203-206.  doi:10.1016/j.cropro.2016.09.014  

Witmer, G.W., S. Raymond-Whish, R.S. Moulton, B.R. Pyzyna, E.M. Calloway, C.A. Dyer, L.P. Mayer, and P.B. Hoyer. 2017. Compromised fertility in free feeding of wild-caught Norway rats (Rattus norvegicus) with a liquid bait containing 4-vinylcyclohexene diepoxide and triptolide. Journal of Zoo and Wildlife Medicine 48(1):80-90.  doi: 10.1638/2015-0250.1
               

2016                                

Baldwin, R.A., R. Meinerz, and G.W. Witmer. 2016. Are chloecalciferol plus anticoagulant rodenticides a viable option for field rodents? Proceedings of the 27th Vertebrate Pest Conference 27:407-410. 

Baldwin, R.A., R. Meinerz,  and G.W. Witmer. 2016. Cholecalciferol plus diphacinone baits for vole control: a novel approach to a historic problem.  Journal of Pest Science 89:129-135.  doi:  10.1007/s10340-015-0653-3   

Eisemann, J.D., R.S. Moulton, and G.W. Witmer. 2016. The use of forced gas rodent burrow fumigation systems and the potential risk to humans. Proceedings of the 27th Vertebrate Pest Conference 27:411-418.

Pyzyna, B., S. Whish, C.A. Dyer, L.P. Mayer, G. Witmer, and R. Moulton. 2016.  Free ranging wild-caught Norway rats have reduced fecundity after consuming liquid oral fertility bait containing 4-Vinylcyclohexene Diepoxide and Triptolie. Proceedings of the 27th Vertebrate Pest Conference 27:314-316. 

Witmer, G.W. 2016. Evaluation of foraging preferences and their corresponding nutritional content for northern pocket gophers (Thomomys talpoides). Proceedings of the 27th Vertebrate Pest Conference 27:322-324.

Witmer, G.W., N.P. Snow, and R.S. Moulton. 2016. Retention time of chlorophacinone in black‐tailed prairie dogs informs secondary hazards from a prairie dog rodenticide bait. Pest Management Science 72(4):725-730.  doi:  10.1002/ps.4045   

Witmer, G. W. and R.S. Moulton. 2016. Design of a self-resetting, low-maintenance, long-term bait station for rodent control. Proceedings of the 16th Wildlife Damage Management Conference 21-25.    

Witmer, G.W., R.S. Moulton, and J.L. Swartz. 2016. Evaluation of a food bait block for potential chemical delivery to black-tailed prairie dogs (Cynomys ludovicianus). Proceedings of the 16th Wildlife Damage Management Conference 26-32.

Witmer, G.W., R.S. Moulton, and R.A. Baldwin. 2016. An evaluation of potential repellents for botta's pocket gopher. Proceedings of the 27th Vertebrate Pest Conference 27:325-331. 

Werner, S.J., S.T. DeLiberto, R.A. Baldwin, and G.W Witmer. 2016. Repellent application strategy for wild rodents and cottontail rabbits. Applied Animal Behaviour Science 185:95-102.  doi:10.1016/j.applanim.2016.10.008 

2015

Baldwin, R. A., R. Meinerz, H.E. Jantz, and G.W. Witmer. 2015. Impact of capture and transportation methods on survival of small rodents during relocation events. The Southwestern Naturalist 60(4):385-389.  doi:  10.1894/0038-4909-60.4.385  

Witmer, G.W., N.P. Snow, and R.S. Moulton. 2015. Efficacy of potential chemical control compounds for removing invasive American bullfrogs (Rana catesbeiana). SpringerPlus 4(1):497.  doi: 10.1186/s40064-015-1319-6

2014

Pitt, W.C., and G.W.Witmer. 2014. Invasive vertebrate species and the challenges of management. Proceedings of the 26th Vertebrate Pest Conference 26:12-14.  

Witmer, G.W., W.C. Pitt, and G. Howald. 2014. Invasive rodent ecology, impacts, and management with an emphasis on the United States. Proceedings of the 26th Vertebrate Pest Conference 26:15-20.  

Witmer, G.W., and R.S. Moulton. 2014. Improving invasive house mice control and eradication strategies via more effective rodenticides. 2014. Proceedings of the 26th Vertebrate Pest Conference 26:67-72.  

Witmer, G.W., R.S. Moulton, and R.A. Baldwin. 2014. An efficacy test of cholecalciferol plus diphacinone rodenticide baits for California voles (Microtus californicus Peale) to replace ineffective chlorophacinone baits. International Journal of Pest Management. doi: 10.1080/09670874.2014.969361.

Witmer, G.W., N.P. Snow, and R.S. Moulton. 2014. Responses by wild house mice (Mus musculus) to various stimuli in a novel environment. Applied Animal Behaviour Science 159:99-106.  doi: 10.1016/j.applanim.2014.07.007.

Shiels, A.B., W.C. Pitt, R.T. Sugihara, and G.W. Witmer. 2014. Biology and impacts of Pacific Island invasive species. 11. The Black Rat, Rattus rattus (Rodentia: Muridae). Pacific Science 68(2): 145-184. doi: 10.2984/68.2.1.

Pitt, W.C., G.W. Witmer, S.M. Jojola, and H. Sin. 2014. Potential citric acid exposure and toxicity to Hawaiian hoary bats (Lasiurus cinereus semotus) associated with Eleutherodactylus frog control. Ecotoxicology 23(3): 429-436. doi: 10.1007/s10646-014-1208-8.

Witmer, G.W. Evaluating habitat manipulations and rodenticides to protect seedlings from rodent damage at restored landfills in New York. 2014. Restoration Ecology 22(2): 178-184. doi: 10.1111/rec.12056.

Witmer, G., K. Horak, and R. Moulton. 2014. New rodenticides: an update on recent research trials. Proceedings of the Wildlife Damage Management Conference 15: 79-85.

2013

Witmer, Gary W., N.P. Snow, R.S. Moulton. 2013. The effects of vitamin K1-rich plant foods on the efficacy of the anticoagulant rodenticides chlorophacinone and diphacinone, used against Montane Voles (Microtus montanus). International Journal of Pest Management 59(3): 205-210. doi: 10.1080/09670874.2013.816453

2012

Savidge, J. A., M. W. Hopken, G. W. Witmer, S. M. Jojola, J. J. Pierce, P. W. Burke, and A. J. Piaggio. 2012. Genetic evaluation of an attempted Rattus rattus eradication on Congo Cay, U.S. Virgin Islands, identifies importance of eradication units. Biological Invasions 14:2343-2354.

Witmer, G. 2012. Eradication of invasive rodents on islands of the United States. Pages 91-92 in S. N. Frey, editor. Proceedings of the 14th Wildlife Damage Management Conference. The Wildlife Damage Management Working Group of The Wildlife Society, Nebraska City, NE. Wildlife Damage Management Working Group of The Wildlife Society.

Witmer, G. and P. Fuller. 2012. Vertebrate species introductions in the United States and its territories. Pages 85-86 in S. N. Frey, editor. Proceedings of the 14th Wildlife Damage Management Conference, Nebraska City, NE. The Wildlife Damage Management Working Group of The Wildlife Society.

Witmer, G., and W. Pitt. 2012. Invasive rodents in the United States: ecology, impacts, and management. Pages 47-75 in J. Blanco and A. Fernandes (Eds.), Invasive Species: Threats, Ecological Impacts and Control Methods. Nova Science Publishers, Inc., NY.

Witmer, G., T. R. Sheffels, and S. R. Kendrot. 2012. The introduction, impacts, and management of a large, invasive, aquatic rodent in the United States. Pages 49-89 in D. C. Abreu, and S. L. De Borbon, editors. Marshes : Ecology, Management and Conservation. Nova Science Publishers, Inc.

Witmer, G.W., N.P. Snow, R.S. Moulton, and J.L.Swartz. 2012. An assessment of seedling damage by wild house mice (Mus musculus) and wild deer mice (Peromyscus spp.). Canadian Journal of Forest Research 42:1168-1172. DOI: 10.1139/x2012-065.

2011

Fall, M. W., M. L. Avery, T. A. Campbell, P. J. Egan, R. M. Engeman, D. Pimentel, W. C. Pitt, S. A. Shwiff, and G. W. Witmer. 2011. Rodents and other vertebrate invaders in the United States. Pages 381-410 in D. Pimentel, editor. Biological invasions, 2nd edition. CRC Press, Boca Raton, Florida.

Snow, N. P., and G. W. Witmer. 2011. A field evaluation of a trap for invasive American bullfrogs. Pacific Conservation Biology 17:285-291.

Witmer, G. W. 2011. Rodent population management at Kansas City International Airport. Human-Wildlife Interactions 5:269-275

Witmer, G. W., and P. L. Fuller. 2011. Vertebrate species introductions in the United States and its territories. Current Zoology 57:559-567.

Witmer, G. W. and P. Hall. 2011. Attempting to eradicate invasive Gambian giant pouched rats (Cricetomys gambianus) in the United States: lessons learned. Pages 131-134 in C. R. Vietch, M. N. Clout,and D. R. Towns, editors. Island invasives: eradication and management. IUCN, Gland, Switzerland.

Witmer, G. W., J. Pierce, and W. C. Pitt. 2011. Eradication of invasive rodents on islands of the United States. Pages 135-138 in C. R. Vietch, M. N. Clout,and D. R. Towns, editors. Island invasives: eradication and management. IUCN, Gland, Switzerland.

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