Penn. game commission deer management program earns praise

HARRISBURG, Pa. — Results of collaborative research conducted by the Pennsylvania Game Commission and U.S. Geological Survey's Pennsylvania Cooperative Fish and Wildlife Research Unit at Pennsylvania State University were published in the scientific journals Behavioral Ecology and The Journal of Wildlife Management.

"Publication of these peer-reviewed papers demonstrates recognition of the scientific quality of wildlife research conducted in Pennsylvania," said Carl G. Roe, Game Commission executive director. "The findings of this important fieldwork have helped shape the Game Commission's deer management program.

"Additionally, publication of these papers demonstrates the value of the collaborative research being conducted by the Game Commission and the Pennsylvania Cooperative Fish and Wildlife Research Unit. It's a partnership that spans decades and one that we and Pennsylvania wildlife have been fortunate to have for so long. Neither the Game Commission nor the Cooperative Research Unit could have completed these studies individually."

The two recent articles report results from study of white-tailed deer bucks that occurred in Pennsylvania from 2001 to 2005 as part of the Game Commission's evaluation of changes in antler restrictions.

"As part of the buck study, the Game Commission and Cooperative Research Unit conducted a large-scale study where management actions were changed and results monitored," Roe said. "Although we regularly report harvest changes and results from this study in annual reports, which are posted on our Web site, www.pgc.state.pa.us, these articles report additional results that have increased our understanding of dispersal behavior and its implications to such practical issues as attempting to manage the spread of diseases, such as chronic wasting disease (CWD)."

Dr. Duane Diefenbach, who heads up the Cooperative Research Unit, said the two recently-published articles detail how field studies provide important findings that improved the science used to manage whitetails.

"The buck study was designed to evaluate the impact on Pennsylvania's deer population caused by the new antler restrictions that were put in place in 2002," Diefenbach said. "This research sheds new light on dispersal behavior of deer and provides insight for other practical management concerns such as disease spread."

In the "dispersal causes" paper, the Game Commission's new method of monitoring deer population trends formed the basis of the analysis.

"Publication of this paper demonstrates the scientific acceptability of the general procedures used in our modified population monitoring method," Roe said.

Roe pointed out that this is the third article in four years to validate methods used by the Game Commission to manage the Commonwealth's deer herd. In 2004, The Journal of Wildlife Management published a paper reviewing the Game Commission's deer harvest reporting rate and estimating procedures.

Diefenbach noted the article that appeared in The Journal of Wildlife Management provides another tool for deer managers facing the threat of combating wildlife diseases, such as CWD.

"This paper uses field data from Pennsylvania and Maryland to develop a predictive model of dispersal distances of yearling male white-tailed deer," Diefenbach said. "The benefit to this model is that it provides a simple tool managers can use in other areas to assess possible movements of deer in their area.

"As a result, wildlife managers can use the model to assess the potential spread of the disease rather than having to implement costly and time-consuming field studies. Critical decisions that might otherwise have to be based on 'best guesses' now can be based on real data."

With the presence of CWD in free-ranging deer herds across the United States, including New York and West Virginia, understanding how deer move across the land is important for managers attempting to understand and/or contain spread of diseases. Dispersal by yearling male white-tailed deer is one method of spreading disease.

"This work, based on research in Pennsylvania and in Maryland, developed a general management tool that managers across the eastern US can use to save considerable financial, personnel, and other resources if faced with detection of CWD," Diefenbach said. "Wildlife managers and researchers can now develop reasonable expectations of how far a disease is likely to spread due to dispersal.

"And, while CWD has not been detected in Pennsylvania deer or elk, this is important information in our efforts to prepare should CWD ever be found within our borders."

Dr. Christopher Rosenberry, Game Commission Deer and Elk Section supervisor, noted that the Behavioral Ecology paper — co-authored by Rosenberry, Diefenbach, Bret Wallingford, Game Commission Deer and Elk Section biologist; and Dr. Eric Long, a former graduate student at Pennsylvania State University — investigated changes in dispersal behavior that occurred when Pennsylvania changed its antler restrictions and increased antlerless harvests.

"These changes in hunting regulations increased the number of adult males in the population and decreased the number of adult females," Rosenberry said. "This resulted in changes in dispersal behavior of yearling male white-tailed deer.

"Each spring during the fawning season and each fall during the time leading up to the peak of the rut, 70 percent of yearling male white-tailed deer across Pennsylvania leave the areas where they were born. On average, these deer will move about three to six miles, but we have recorded movements greater than 30 miles."

Rosenberry noted that, in recent years, different studies have identified different causes of yearling male dispersal.

"For example, an early 1990s study in Virginia identified adult does as the cause for yearling male dispersal," Rosenberry said. "This became a part of deer management recommendations where increasing antlerless harvests could increase the proportion of bucks in a population.

"Later, studies that I conducted as a graduate student in Maryland identified competition among yearling males as a likely cause of dispersal. The present study demonstrated the likely involvement of both mechanisms in dispersal of white-tailed deer."

For more information on the Pennsylvania Game Commission's deer management program, visit the agency's Web site, www.pgc.state.pa.us and click on "Deer Program" in the "Quick Clicks" box in the right-hand column of the homepage.