Posted: May 6, 2016

A GPS study tracks deer damage to forests.


Innocent as they may seem, white-tailed deer can be agents of destruction.

"Deer are browsers," says Christopher Rosenberry, supervisor of deer and elk management with the Pennsylvania Game Commission. "Too much browsing may eliminate the small trees in the forest. If there's a timber harvest or an ice storm or something that removes the canopy, and those young trees do not exist under the canopy, you can potentially lose your forest."

Entering its third year, a study--led by Duane Diefenbach, adjunct professor of wildlife ecology, and Marc McDill, associate professor of ecosystem science and management--uses sophisticated global positioning system (GPS) technology to investigate the effects of deer browsing on forest vegetation. The Deer-Forest Study is a collaborative effort among Penn State, the Pennsylvania Game Commission, the Pennsylvania Department of Conservation and Natural Resources, and the Pennsylvania Cooperative Fish and Wildlife Research Unit.

The study involves outfitting deer in three areas--Rothrock, Bald Eagle, and Susquehannock state forests--with GPS collars that monitor each deer's location. The field researchers also collect data on vegetation levels in the locations visited by each deer.

"The objective of the research is to look at the simultaneous effects of deer browsing, competing vegetation, and soil conditions on vegetation" says Diefenbach, adding that the GPS technology has been instrumental in the success of the project. "The collars transmit data to a satellite, which then transfers that information to us via the Internet," he says. "Using this, we can get hundreds of locations per day on one animal. It's a game changer in understanding animal movements and how they respond to environmental factors and human activity."

According to Diefenbach, the GPS collars have provided insight into how adult male deer are able to avoid being killed by hunters. "Because we've been following their movements every 20 minutes during the hunting season, you can see they respond incredibly quickly to the hunters," he said. The researchers feel that their work is an important step in preserving forests for future generations.

"When we look at a forest, a lot of times we just see the big trees," says Rosenberry. "But in order for those big trees to exist, there had to be small trees at some point in the past. Those small trees that are growing today will be the forests of tomorrow." -- Rachel Garman

Hunters Can Help

Deer hunters have the greatest effect on deer populations. Researchers in the college would like to learn more about how deer respond to hunters and how harvests can affect deer populations in a local area. To better understand the role of hunters, the researchers need to know who hunts on the study areas.

Deer will be managed differently in four locations (two in Susquehannock State Forest) with the help of hunters. Forest conditions will be monitored to see how they respond to real-world deer and forest management activities.

To help, hunters can provide their name and hunting license CID#. After the hunting seasons, hunters will have an opportunity to share their hunting experiences and opinions.

Participate in the Study

Registration will open in mid-July.

Bald Eagle State Forest DMAP No. 2108

Rothrock State Forest DMAP Nos. 1881, 1883, 2109, 2110

Susquehannock State Forest DMAP Nos. 2101, 2102