Why can't we just increase natural predators in town to control deer numbers?
Why can't we just increase natural predators in town to control deer numbers?
What animals prey on White-tailed Deer?
The major predators of white-tailed deer include coyotes, black bears, bobcats, foxes, grizzly bears, mountain lions, and wolves. Many of these, such as foxes and bobcats, prey primarily on fawns. Others, such as mountain lions and wolves, prey heavily on adult deer and may have a significant effect on controlling deer populations. Coyotes and black bears may take both fawns and adult deer, depending on the conditions and other predators present (Ballard, 2011). Only two of these predators - coyotes and foxes - are present in West Seneca, and neither appears to exert sufficient predation pressure on deer to control the population. Foxes are limited to preying on newborn fawns, and lack the potential to regulate the deer population. However, people often inquire about the feasibility of increasing coyote populations to control deer, or about the possibility of restoring or increasing populations of other native large carnivores, such as black bears, mountain lions, or wolves.
Mountain lions and wolves were extirpated from New York State in the 1800s. Although these species are native to New York and do have the predatory potential to impact deer populations, there is little habitat available to support them outside Adirondack Park and the Catskills region (Gilbert et al., 2017; NYSDEC, 2017). Similarly, black bear are absent from the area around West Seneca, except for the occasional transient bear moving through, because there is not sufficient habitat to support a population (NYSDEC, 2014).
Coyotes, on the other hand, are a common species throughout Western New York, including urban and suburban neighborhoods. They appear to cause significant mortality in fawns (Kilgo et al., 2012) and are known to hunt adult deer in some cases (Chitwood et al., 2014). However, data on the ability of coyotes to regulate deer population is mixed. A study of coyote predation on deer in the southeastern US suggested that deer population declines there may have been linked to recent colonization by coyotes, particularly through heavy predation on fawns, but noted that the evidence did not fully establish a cause-effect relationship between coyote presence and lower numbers of deer (Kilgo et al., 2010). Cherry et al. (2016) found that coyote predation may influence deer populations in indirect ways. They found that in addition to killing deer, coyote predation may actually lower reproduction rates in deer. However, a broader study examining deer and coyote population trends in six states over a period of more than 30 years concluded that coyotes do not appear to be controlling deer populations over large areas (Bragina et al., 2019).
Is it feasible to reintroduce large predators (or increase populations of those that are here) to control deer?
The short answer to this is no, it is not feasible to do this. One major reason for this is the lack of suitable habitat for these animals. Mountain lions and wolves have no suitable habitat in New York outside the Adirondack and Catskill regions. Even for large predators that are already found here, such as coyotes and black bears, habitat is a major limiting factor. However, the main reason that increasing populations of coyotes or other carnivores is not an option is simply the lack of human tolerance for having these species in their own backyards. As coyotes have increasingly spread into urban and suburban areas over recent years, the frequency of human-coyote conflict has risen as well. Coyote attacks on humans and pets appear to have increased - particularly in situations where coyotes have been fed by people. Fear of coyotes attacking children or pets are commonly cited as a reason for people's fear and desire to keep coyotes out of their neighborhoods (Hudenko et al., 2008, White and Gehrt, 2009). So while coyotes are present in West Seneca - and are likely having some impact on the deer population through predation on fawns (and even some adults) - focusing efforts on increasing coyotes would likely mean trading one human-wildlife conflict for another, and would not necessarily result in a significant reduction of deer.
References:
Ballard, W. 2011. Predator-Prey Relationships. In: Hewitt, D.G. (ed.). 2011. Biology and Management of White-tailed Deer. CRC Press, Boca Raton, FL. pp. 251-286.
Bragina, E.V., R. Kays, A. Hody, C.E. Moorman, C.S. DePerno, and L.S. Mills. 2019. Effects on White-Tailed Deer Following Eastern Coyote Colonization. Journal of Wildlife Management 83(4): 916-924. Accessed at https://www.jstor.org/stable/pdf/26689591.pdf?casa_token=Rr16FNnEA1gAAAAA:8csxNkXGKpuV8UyybyP1RTaEsceTlQkb5xSVCTSu6av8oVq1DCIWjaiHSjjWWfMrOOqSnLe_cgILtHt6cti5aycPnRv9SGdBeh1vxF8A5JL4Kzd_-2xA
Cherry, M.J., K.E. Morgan, B.T. Rutledge, L.M. Conner, and R.J. Warren. 2016. Can Coyote Predation Risk Induce Reproduction Suppression in White-tailed Deer? Ecosphere 7(10): e01481. Accessed at https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecs2.1481
Chitwood, M.C., M.A. Lashley, C.E. Moorman, and C.S. DePerno. 2014. Confirmation of Coyote Predation on Adult Female White-Tailed Deer in the Southeastern United States. Southeastern Naturalist 13(3): N30-N32. Accessed at https://bioone.org/journals/southeastern-naturalist/volume-13/issue-3/058.013.0316/Confirmation-of-Coyote-Predation-on-Adult-Female-White-Tailed-Deer/10.1656/058.013.0316.short
Gilbert, S.L., K.J. Sivy, C.B. Pozzanghera, A. DuBour, K. Overduijn, M.M. Smith, J. Zhou, J.M. Little, and L.R. Prugh. 2017. Socioeconomic benefits of large carnivore recolonization through reduced wildlife-vehicle collisions. Conservation Letters 10(4): 431-439. Accessed at https://conbio.onlinelibrary.wiley.com/doi/epdf/10.1111/conl.12280
Hudenko, H.W., W.F. Siemer, and D.J. Decker. 2008. Humans and Coyotes in Suburbia: Can Experience Lead to Sustainable Coexistence?HDRU Series No. 08-9, Cornell University Human Dimensions Research Unit, Ithaca, NY. Accessed at https://ecommons.cornell.edu/bitstream/handle/1813/40432/HDRUReport08-9.pdf?sequence=1
Kilgo, J.C, H.S. Ray, C. Ruth, and K.V. Miller. 2010. Can Coyotes Affect Deer Populations in Southeastern North America? Journal of Wildlife Management 74(5): 929-933. Accessed at https://www.jstor.org/stable/pdf/40665165.pdf?casa_token=cgGR3CsZ5UQAAAAA:5Jaf0ydJf_5Q6GrvImGUPkVenRbStsBNkVYj7RYe0OYrBE1b6LhyaLj-j6-9Pq9dzDQM4t3NrkksrbkmVnfpe6-3iSHem9VKE95t1QgTniwLmBuu7qSA
Kilgo, J.C., H.S. Ray, M. Vukovich, M.J. Goode, and C. Ruth. 2012. Predation by Coyotes on White-Tailed Deer Neonates in South Carolina. Journal of Wildlife Management 76(7): 1420-1430. Accessed at https://www.srs.fs.usda.gov/pubs/ja/2012/ja_2012_kilgo_002.pdf
NYSDEC. 2014. Black Bear Management Plan for New York State, 2014-2024. Accessed at https://www.dec.ny.gov/docs/wildlife_pdf/bearplan2014.pdf
NYSDEC. 2017. Species Status Assessment: Canis lupus. Accessed at https://www.dec.ny.gov/docs/wildlife_pdf/sgcnwolf.pdf
White, L.A. and S.D. Gehrt. 2009. Coyote Attacks on Humans in the United States and Canada, Human Dimensions of Wildlife, 14:6, 419-432. Accessed at https://www.tandfonline.com/doi/pdf/10.1080/10871200903055326?casa_token=fb8iQfSQOgsAAAAA:hXs_l7QutXirDTLg6xQbtbMa3UafhNkW3PONNkd6iUFsaFVL_vymJLS8C26-uKe_2QQ7HeJbB8RdQA