About the Study

Researchers from Penn State, U.S. Geological Survey, Pennsylvania Game Commission, and Pennsylvania DCNR Bureau of Forestry will be monitoring deer populations and forest changes in Rothrock, Bald Eagle, and Susquehannock State Forests.

By carefully monitoring deer populations and diversity and growth rates of forests in these areas, this study will lead to a better understanding of the complex relationships between our state’s deer herd and the forest.

Deer are an important part of Pennsylvania’s forests. However, too many deer can change forests in ways we may not like — for example, by eating too many seedlings of some tree species.

But deer are not the only issue. Forest managers have to deal with problems such as invasive plants, insect outbreaks, soil acidity, and tree diseases.

Four study areas, ranging in size from 25 to 40 square miles, have been selected. One pair of study areas is in the center of the state, in the Rothrock and Bald Eagle State Forests, and one pair is in the north, in the Susquehannock State Forest.

Deer in these study areas will be managed differently with the help of hunters.  Forest conditions will be monitored to see how they respond to real-world deer and forest management activities.

During the study, researchers from Penn State, the U.S. Geological Survey, the Pennsylvania Game Commission, and the Pennsylvania DCNR Bureau of Forestry will carefully monitor deer populations and changes in the species mix and growth rates of plants in the study areas.

Study Objectives

The goals and objectives for this study address the information needs and research questions of each collaborator.

  • Test the assumption that FIA categorical deer impact levels accurately reflect the effect of deer browsing on forest conditions. Identify modifications that could improve the accuracy of monitoring programs of forest conditions in relation to deer browsing.
  • Evaluate the effectiveness of DMAP to increase antlerless harvest in a local area.
  • Monitor hunter behavior and attitudes in response to changes in deer abundance.
  • Test the ability of DCNR’s Vegetation Impact Protocol to detect changes in vegetation in response to changes in deer abundance.

Key Project Personnel

  • Duane R. Diefenbach, U.S. Geological Survey, Pennsylvania Cooperative Fish and Wildlife Research Unit,
  • Marc E. McDill, Pennsylvania State University, Department of Ecosystem Science and Management
  • Emily H. Just, DCNR Bureau of Forestry, Ecological Services Section
  • Christopher S. Rosenberry, Pennsylvania Game Commission, Deer and Elk Section 
  • Bret Wallingford, Pennsylvania Game Commission, Deer and Elk Section
  • Jeannine Fleegle, Pennsylvania Game Commission, Deer and Elk Section 


Fieldwork began in January 2013 with the capture and radio-collaring of deer. During May-August 2013, eight field technicians began collecting vegetation data on 200 permanent plots (50 per study area).  These permanent plots are revisited every other year.  Additional monitoring of areas with planned timber harvests began in 2014.

Current funding will support the project for the period 2013-2022. Preliminary findings are just starting to come about after 3-4 years of this study. Fortunately, this project will be continued beyond the initial 5-year study period in order to better understand how forest management conditions respond to management actions over many years.

Study Areas

Four study areas (see maps), ranging in size from 25 to 40 square miles, have been selected – one each in Rothrock State Forest and Bald Eagle State Forest and two in Susquehannock State Forest. The northern study areas (Susquehannock State Forest) represent northern hardwoods forest types and the southern study areas represent oak-hickory forest types.

Hunter input needed

Do you hunt deer on any of the study areas? If so, we want to hear about your deer hunting experiences. Please register to receive a questionnaire to share your hunting experiences.