National Capital Region Network 2007 Deer Monitoring Report

Bates, Scott

In 2000, the National Capital Region Inventory and Monitoring Network (NCRN) initiated a deer monitoring program to collect information on deer densities. The program is carried out through fall spotlight surveys in Antietam National Battlefield, Catoctin Mountain Park, Chesapeake and Ohio Canal National Historic Park- Gold Mine Tract, George Washington Memorial Parkway – Great Falls Park, Manassas National Battlefield Park, Monocacy National Park, National Capital Parks – East (Greenbelt and Piscataway units), Prince William Forest Park, and Rock Creek Park. Pellet-group counts are used in Harpers Ferry National Historic Park because of the lack of a road network. This report summarizes and analyzes the fall 2007 spotlight surveys and the 2007 fall-winter pellet-group count. Deer populations in the NCRN have become a significant negative factor adversely affecting native forest vegetation and other wildlife. The primary negative effect is a reduction of forest regeneration. This means that there will not be any young trees to replace the forest overstory if the overstory is removed by natural causes (fire, windthrow, disease, etc.). The accepted scientific threshold for densities to impact tree regeneration is 8 per square kilometer or 20 per square mile. The lack of shrubs and young trees results in little or no nesting cover for ground-nesting bird species. Information on deer density and sex ratios is collected during the survey. Both of these measures contribute information about the abundance and structure of the deer population, though density remains the single most important piece of information to indicate if the deer population may be impacting forest vegetation. All park units sampled except for Prince William Forest Park and the West Virginia sections of Harpers Ferry National Historic Park had densities indicating overpopulation. This is the first year that any NCRN park surveyed by spotlight counts had what is considered a normal population level. Prince William Forest Park also became the first park to show a statistically significant (decreasing) trend in their deer population. In 2007 there were fewer parks with buck:doe ratios and fawn:doe ratios that would indicate an overpopulation situation. Only one park had a low fawn:doe ratio. The number of parks with relatively high doe populations relative to bucks fell from 7 to 5. All NCRN parks currently have or have had deer density levels that indicate deer abundances that interfere with forest regeneration and associated wildlife habitat.

National Capital Region Network 2007 Deer Monitoring Report

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