DEER MANAGEMENT SERIES, NO. 17:

FLAWED HARVEST CLAIMS About 50 deer per square mile

would be needed to sustain PGC's high harvest claims.

By John Eveland

October 17, 2014


Since 2010, the author has scientifically assessed the Pennsylvania Game Commission's annual deer harvest estimates in order to determine their validity. In each of these four years, PGC has claimed increasingly higher annual statewide harvests: 316,240 deer in 2010, 336,200 in 2011, 343,110 in 2012, and 352,920 in 2013. This document provides an independent, scientific assessment of PGC's 2013 estimated deer harvest. It is intended to provide sportsmen and decision makers with sound scientific information toward making wise deer management decisions. Readers should remember that the projected herd sizes in this report do not represent the author's estimate of the actual number of deer that exist in Pennsylvania, but, instead, represent the number of deer that would be required in order for the PGC to sustain its claimed annual harvests. Two scenarios are considered: (1) a deer population and harvest dynamic that is uninfluenced by predation; and (2) separate calculations that include the impacts of predation. It should, also, be noted that the PGC does not consider the impact of predation in deer management decisions, stating, "We have no evidence to suggest that fawn survival rates we observed were preventing population growth."

Scenario 1: Predation Is Not Considered. If predation by coyotes and bears had no impact on fawn survival rates (as is claimed by the PGC), then 1,422,011 deer would be required in order for the PGC to harvest 352,920 deer – the agency's published 2013 harvest estimate. The associated densities of deer that would be required to produce a harvest of 352,920 deer would be: (1) 54 deer per square mile (dpsm) on all forested land within the state; (2) 40 dpsm on all forest and agricultural lands, combined; and (3) 32 dpsm on all land area throughout the state (including developed areas, towns, and city streets).

Scenario 2: The High Impact of Predation. A PGC/Penn State study in 2000-01 indicated that 22.5% of the total fawn crop succumbed to predation – about evenly by bears and coyotes and a few to bobcats. For decades, the bear population has remained relatively stable at 20-25 thousand bears, and it appears that prior to 2000 the deer population had been able to cope with the roughly 10% fawn loss attributed to bears. However, it is estimated that the coyote population has rapidly increased to as many as 250,000. The increasing impact by coyotes could exceed the reproductive capacity of the herd to grow and possibly even to remain stable. Other studies indicate that coyote predation throughout the East currently accounts for 50% of fawns, while in the Southeast coyotes inflict a 75% early impact on fawns. The Southeast study concluded that when combined with doe hunting, deer populations are unable to sustain themselves in the face of such heavy coyote predation.

Using the 22.5% predation rate from PGC's 2000-01 study, 1,739,746 deer would be required in the state in order to provide a sustained harvest of 352,920 deer, and 2.2 million deer at the 50% fawn-predation rate. The corresponding densities of deer would be, respectively: (1) 66-83 dpsm on all forested land in the Commonwealth; (2) 49-62 dpsm an all forest and agricultural lands, combined; and (3) 39-49 dpsm on all land area within the state.

Conclusion. A PGC study indicated that 14 years ago 22.5% of fawns were being lost to predation. Since then, studies throughout the East have discovered a 50% fawn-predation rate, indicating that it is fairly certain that fawn predation in Pennsylvania ranges from 22.5-50%. Considering that 66-83 dpsm would be required on all forested lands within the state in order for the PGC to have harvested their claimed 352,920 deer in 2013, or 39-49 dpsm on every square mile of land within the Commonwealth, it is virtually impossible that PGC's deer harvest claims are accurate. Therefore, PGC's improbably high 2013 harvest estimate of 352,920 deer and other recent annual harvest estimates cannot be justified by scientific analysis, and can only be explained by incompetence or deception.

 

 

 

 

©2011 • Unified Sportsmen of Pennsylvania