Does Predator Control Work on Coyotes?
Predator control can be a valuable wildlife management tool to improve ungulate populations. Though one predator has largely eluded management as it expands its range throughout the United States. Enter the Coyote (Canis Latrans), arguably the most vilified large mammal in North America. Despite nearly 150 years of trying to control (and sometimes completely remove) the coyote, the canine is doing increasingly well, and unfortunately that often means many ungulate populations suffer badly. So what are modern wildlife agencies doing to mange the coyote, and is it having a positive effect?
A recent study conducted by USDA Wildlife Services in South Carolina attempts to address some of the issues caused by the growing coyote population. The research team identified a section of the state known to have a declining white-tailed deer population. Coyotes were the dominant predator, gobbling up spring fawns at a rate that was unsustainable for the deer population. The team wanted to know how many coyotes would need to be removed to have a positive impact on fawn recruitment (the number of fawns per doe that grow to be 6 months old).
The research team monitored the deer population for four years prior to employing their strategy to establish a baseline. Following the monitoring period, they began removing as many coyotes as possible. The team removed 474 coyotes over a 300 square kilometer range, or roughly 78% of the coyote population within that area. During this treatment period, the team also collared 216 fawns to study changes in predation rates by coyotes.
The results showed a temporary increase in fawn recruitment following the aggressive removal of coyotes, but the effect rebounded shortly after. Even by removing 78% of the the coyotes in the study area, the deer population increase was not significant. The remaining 133 coyotes (474 is 78% of 607 total coyotes) had essentially the same impact on the deer that all 607 coyotes had at the beginning of the study.
Reasons for this bleak result may vary among regions, but recent studies seem to point to the Coyote’s amazing ability to positively adapt to intensive hunting pressure. Current research indicates that when coyotes are aggressively removed, neighboring coyote packs immigrate quickly into the vacant areas. Coyote females have also been shown to increase their litter size when under threat, and even long term predator control may not always produce desired results.
Despite the sobering conclusion, a few research projects have shown that removing coyotes immediately before and during the spring fawn drop can have positive effects on deer recruitment. Though the population of coyotes may bounce back soon after removal. Overall, it appears that traditional methods of predator control are struggling to address the issue of coyote predation on deer.
Works Cited in Order of Appearance
1. Kilgo, John C., Vukocich, Mark., Ray, H. Scott., Shaw, Christopher. (2014) Coyote removal, understory cover, and survival of white‐tailed deer neonates. Journal of Wildlife Management, Volume 78, Issue 7. Retrieved from: https://onlinelibrary.wiley.com/doi/full/10.1002/jwmg.764
2. Kilgo, John C., Vukovich, Mark., Shaw, Christopher., Conroy, Michael J. (2017) Reproductive characteristics of a coyote population before and during exploitation. Journal of Wildlife Management, Volume 81, Issue 8. Retrieved from: https://onlinelibrary.wiley.com/doi/full/10.1002/jwmg.21329
3. Rosen, Julia. (2017) The cost of the bighorn comeback. High Country News, May Edition. Retrieved from: https://www.hcn.org/issues/49.9/Wildlife-Services-mountain-lion-killing