Game populations across the country are generally the healthiest they have been in generations. However, for species such as elk that have experienced significant declines, some people argue that a single predator is driving the decline. Even when game populations are robust – as
Game populations across the country are generally the healthiest they have been in generations. However, for species such as elk that have experienced significant declines, some people argue that a single predator is driving the decline. Even when game populations are robust – as is the case with white-tailed deer, wild turkey, and waterfowl – there are perceptions that a single predator has a disproportionate impact on the population.
Predation rates vary from one area to the next based on habitat, human populations, and climate. It’s a complex ecological puzzle that scientists are slowly piecing together. Let’s separate myth from fact and look at what the current data tells us about predation of four popular game species.
White-tailed deer are America’s most widespread and popular big game animal. Whitetail numbers have rebounded strongly since the turn of the 20th century, when the U.S. population was estimated at less than a half-million deer. Today, whitetail numbers nationwide hover at around 30 million animals.
In many areas of the country, whitetails are intensely managed. Part of this management has involved the removal of key predatory species – specifically, the coyote. While there’s certainly evidence that suggests coyotes prey on deer, are they the whitetail’s primary natural predator?
In a 2010-2011 study of cause-specific mortality rates for white-tailed deer, researchers from the Wisconsin Division of Natural Resources and the University of Wisconsin determined that of the more than 300 deceased whitetails studied, the cause of mortality varied by location. In the northern region of Wisconsin – primarily forest area with low human population densities – 26 percent of deer mortalities were the result of non-human predation. Mature deer were killed by wolves (4 yearlings), bobcats (1 doe, 2 yearlings), black bears (1 doe), coyotes (1 yearling, 1 doe), and unknown predators (2 bucks). Fawns were lost to predation by black bears (5 fawns), bobcats (2), coyotes (1), unknown canids (2), and unidentified species (4).
In the more agricultural area of eastern Wisconsin, predation rates were much lower. There was not a single event of predation on radio-collared adult deer. More than 60 percent of the mature deer were taken by hunters and another 24 percent were killed as a result of vehicle collisions. Disease and starvation also factored into adult deer deaths. Fawn predation occurred here but at lower rates than in the northern forest: 4 were killed by coyotes, 1 by a black bear, and 1 by an unidentified predator.
A 2004 study in Pennsylvania showed disparity between primary predators in agricultural and forested areas as well. In that study, predation accounted for almost 70 percent of fawn deaths in forested areas and only 17 percent of fawn deaths in agricultural areas. Coyotes were the most prevalent predators on fawns in the forested areas tested, accounting for more than 60 percent of fawn deaths. Black bears killed 12.5 percent of radio-collared fawns in forest habitat, and bobcats were responsible for 7.3 percent of predation. By contrast, bears were responsible for 36.6 percent of predation events on fawns in the agricultural areas while coyotes accounted for 31.7 percent. (Bobcats did not kill any fawns in agricultural areas in the Pennsylvania study.)
Although coyotes are responsible for a high percentage of fawn deaths in some areas, they are not the only predators responsible for fawn losses. In northern areas, where they face greater competition from wolves, coyotes prey on deer less frequently. Some predators also target specific age classes of deer: Black bears primarily prey on young fawns while wolves tend to focus on yearlings. Bobcats seem to be more varied in their selection, killing both adult and young deer. While coyotes are common predators of fawns, they seem less likely to take on adult deer.
Like all ground-nesting birds, wild turkeys are particularly vulnerable to predation before chicks hatch. Even after birth, turkey poults are common prey for many mammalian and avian predators.
Cause-specific mortality – knowing exactly which predatory species is responsible for the death of a monitored game species – can be difficult to track. There’s little question that some predators have a higher rate of predation than others, though.
A 2010-2015 telemetry study of wild turkey hens in Pennsylvania found that 32 percent of mortalities were due to mammalian predation, 11 percent to avian predation, and 7 percent to unknown predation, reports Mary Jo Casalena, a wild turkey biologist for the Pennsylvania Game Commission. Identified predators ranged from hawks to bears.
The species that accounted for the most deaths was bobcats, having killed three hens during the nesting/rearin