Are Predators Hurting Our Deer Herd?

NR113_14_PredatorsIf you want to start a lively discussion on Pennsylvania wildlife, just mention coyotes.

There might be no other animal that so intrigues the state’s residents, and it’s easy to explain why.

The coyote is surrounded by mystery. It’s inhabited some parts of the state since the 1930s, but it’s a relative newcomer in others. Game Commission biologists are finding indications the coyote population is increasing in some areas of the state, yet even those who log endless hours in the Pennsylvania outdoors might go their lives without seeing one in the wild.

Add to that the false, recurring rumors coyotes were stocked by insurance companies, and the idea that coyotes ravage the deer populations so important to Pennsylvania hunters, and the reasons for coyote’s mystique become even clearer.

Wildlife biologists with the Pennsylvania Game Commission have met with leading biologists from across the country in an effort to better understand the influence of predators on deer populations.

“There are several predators in Pennsylvania that absolutely do kill deer, specifically young fawns,” said Chris Rosenberry, who heads the Game Commission’s deer and elk section. “Coyotes and bears top the list.”

In managing Pennsylvania’s deer populations, Rosenberry said, the agency annually monitors fawn production and has the ability to compensate for fawns lost to predators and other causes by controlling the number of antlerless deer licenses allocated.

Game Commissioner David Putnam, of Centre Hall, said adjusting the allocation is an effective tool.

“However, this does not answer what is on the minds of Pennsylvania’s hunters; what impact are predators actually having on the state’s deer herd?” Putnam said.

The Game Commission studied the effects of fawn predation back in 2001. The study found about half of all fawns born each spring survived to see the fall hunting seasons. Predators including coyotes, bears, bobcats and fishers were responsible for killing about 22 percent of the fawns that died.

Game Commissioner James J. Delaney Jr., of Wilkes-Barre, said deer and predator populations, as well as habitat conditions, all have changed since the last study.

“For most of my seven years as commissioner, I have heard the concerns of many sportsmen across the state with regard to the effects of predators on white-tailed deer,” Delaney said. “We’ve done some good research work on this subject in the past, but opinions about predator impacts on deer still vary. By pulling together some of the top researchers in the country, we’ve entered into a conversation that will yield even more valuable input on the matter.”

Leading biologists from the U.S. Forest Service, Penn State, the University of Georgia, Mississippi State University, the New York State Department of Environmental Conservation, the University of Alberta, and the Quality Deer Management Association were among those who provided input on evaluating the impact of predators on the state’s deer.

“These biologists have led research throughout the eastern United States looking at the impact of predation on deer,” said Game Commission Executive Director R. Matthew Hough. “Their experience and insight from their past and current research is of great interest to the agency, and to our hunters.”

One common opinion offered by some hunters is to use predator control to reduce predation on fawns. However, large-scale predator control repeatedly has been found not to work. For example, U.S. Forest Service researcher John Kilgo conducted research in South Carolina, which found that even when coyotes were taken in higher numbers, other coyotes quickly filled the void created by their absence.

“There is no doubt that predators such as bears and coyotes do prey on fawns,” Kilgo said. “Although some researchers have been able to find instances where increased coyote removal has improved fawn survival at a very local level, coyote removal on a large scale is impossible.”

Mark Ternent, the Game Commission’s bear biologist, said while the Game Commission’s last study on fawn mortality showed differences between separate areas that were studied, how those areas differed in terms of predator abundance was a great unknown.

“When the results suggested fawn predation was different in the two study areas, an explanation was difficult to tease out,” Ternent said. “We knew habitat was different, and bear abundance within those particular wildlife management units was different, but we knew little about the predator communities at a scale as small as the study areas because monitoring predator species was not part of the study.”

The previous study showed fawns might die for any number of reasons. Some die of natural causes, some are struck by vehicles, and one fawn in the study even fell down a well.

Of the fawns taken by predators, nearly equal proportions were taken by coyotes, bobcats and bears.

Ternent noted that Pennsylvania’s bear population is thriving.

“We know we have not seen the statewide population of bears decrease since the last study,” said Ternent.

And Matt Lovallo, who supervises the Game Commission’s game mammals section, noted population changes among other predators, as well.

“Predator communities in Pennsylvania have changed during the past several decades due to increased coyote populations, fisher reintroductions and fishers dispersing in Pennsylvania from West Virginia,” Lovallo said. “Management programs for bobcats and fishers also have targeted conservative harvests, allowing for growth in those populations.

“One area of interest biologists from the Game Commission and other agencies discussed is better understanding the community structure and relative abundance of forest predators in several areas of the state to provide insight on how these species compete for and partition prey resources,” Lovallo said.

Biologists also are evaluating techniques to allow them to estimate abundance of bears, coyotes, bobcats and fishers. In addition, advanced technologies now are available to help biologists gain more insight into fawn mortality.

“We know fawns are more vulnerable to mortality in the first week of life,” said Kip Adams, a wildlife biologist for the Quality Deer Management Association. “However, there are now small transmitters that can be implanted into captured does, and when a fawn is born, a signal is sent alerting researchers and leading them to the exact location, improving monitoring.”

The window within which fawns are preyed upon is relatively short. In actuality, the chances of fawns being preyed upon shrink with each passing day as fawns grow older and are more capable of fleeing from predators. Pennsylvania’s coyotes rarely take healthy adult deer, and ongoing monitoring has indicated predators have had a consistent rather than growing impact on fawns.

As a hunter, Hough said he understands the public’s interest in predators and the importance of tracking predator impacts on fawns. To hundreds of thousands of Pennsylvanians, deer hunting isn’t just a form of recreation, but a passion and a way of life, Hough said. And, like the Game Commission, those hunters want to ensure Pennsylvania’s important deer resource is managed to ensure healthy deer, healthy habitat and hunting opportunity.

“Like the saying goes, knowledge is power,” Hough said. “And the more we know about predator impacts on deer populations, the more empowered we are to comfortably manage deer populations to benefit all Pennsylvanians.”

To that end, the Game Commission is launching a new study into predator impacts on fawns.

The new study is a bit different than its predecessor. It will be conducted in conjunction with ongoing deer research, which, among other things, has helped to reduce costs. But, importantly, the connection to existing projects will help researchers to more efficiently and effectively carry out their work.

For example, the study calls for capturing does this winter to implant the transmitters that signal when fawns are
born. The job is made easier by the fact that some of those does already are fitted with GPS collars as part of a separate study on deer movements.

Likewise, the implanted transmitters will make fawns easier to find and equip with collars.

The new study differs from the original in a second way, too. It will measure the types of predators present in the study areas and their relative abundance, which will be useful for interpreting any differences in survival noted during the study.

Hough touted the strengths in scope of the new study and noted the changes in predator populations and wildlife habitat that have occurred more recently.

“The time has come for new research into predator impacts on deer, and we stand to learn much from this study our staff has worked hard to develop,” Hough said. “Hunters have made it clear: The question of how many fawns are lost to predators is on the minds of many, and this study could well help answer that question.”

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