DEER MANAGEMENT SERIES, NO. 12:

THE DEER HEALTH FALLACY  Science Indicates that Deer Reduction

was not Justified on the Basis of Deer Health

By John Eveland

August 26, 2014


There are two critical questions that need to be addressed regarding the deer-reduction crisis. First, after 14 years of herd reduction toward satisfying the emotional wishes of foresters and environmentalists in PGC, DCNR, and Audubon, have the goals for deer health, forest health, and biodiversity been achieved? Secondly, did problems with deer health, forest health, and biodiversity ever actually exist, or were they simply fabrications to justify herd reduction? Let's scientifically assess the deer-reduction issue – the greatest conservation mistake in the over-one-hundred-year history of the Game Commission.

Regarding Deer Health. One of the principal justifications for herd reduction was to improve the health of deer. To investigate the question of deer health, from 2000-2008 PGC conducted a nine-year embryo-count study. Therefore, the study began in 2000 (the year that herd reduction was initiated), and was not completed until four years after the end of the five-year intensive deer-reduction period. Because the forest was assumed to be in poor health caused by too many deer, it was, also, assumed that deer would be in poor health. Both of these assumptions, however, were not to be the case.

Quoting Christopher Rosenberry from a PGC study, "For 2-year-old females, at least 1.5 embryos per doe was considered good and less than 1.1 embryos was considered poor." In other words, if an average of 1.5 fawns were born per adult doe, then does, fawns, and the deer herd were considered to be in good health. If the average number of fawns born to adult does declined to less than 1.1 fawns per doe, then does and the deer herd were in poor health – also indicating that the forest would be in poor health and unable to sustain the population at that level. Based on the work of Downing and Guynn (1985): "The target value of 1.50 was chosen because it corresponds to a population at maximum sustained yield."

Therefore, after the statewide deer herd had been drastically reduced for nine years between 2000-08 in an effort to improve the health of deer, in 2008 it was learned upon completion of a 9-year after-the-fact study that over each of the nine years of the study deer had always been in good health in every one of the state's 22 Wildlife Management Units – ranging from 1.51 to 1.61 embryos per adult doe throughout all nine years of the study, and averaging 1.57 embryos per doe.

Analyzing each year's data separately, in 2000 the average number of embryos per adult doe for all 22 WMUs combined was 1.61. For 2001 it was 1.59, 1.55 for 2002, 1.61 for 2003, 1.51 in 2004, 1.56 in 2005, 1.56 in 2006, 1.55 in 2007, and 1.60 in 2008. Averaging nine years of data for each WMU provided the following embryo-count results: 1.55 for WMU 1A, 1.61 for 1B, 1.46 for 2A, 1.61 for 2B, 1.50 for 2C, 1.57 for 2D, 1.63 for 2E, 1.45 for 2F, 1.51 for 2G, 1.51 for 3A, 1.44 for 3B, 1.43 for 3C, 1.47 for 3D, 1.57 for 4A, 1.69 for 4B, 1.57 for 4C, 1.53 for 4D, 1.65 for 4E, 1.49 for 5A, 1.72 for 5B, 1.71 for 5C, and 1.84 for 5D. Please keep in mind that for deer (and, therefore, the forest) to be in poor health, embryo counts needed to decline to less than 1.10 per adult doe. Such a low count did not exist - not even close - in any year or WMU. This indicated that before and during herd reduction, both deer and the forest had been in good health.

In 2011, Deer Section Leader Chris Rosenberry stated, "Annual herd reduction is based on accomplishing two goals: deer health and forest health. All WMUs are achieving deer health goals. Fawn/doe ratios have been stable and good since 2003." Thus, Rosenberry had indicated that a second deer-health study lasting from 2003 to 2011 verified that deer had been in good health. Therefore, based on the deer health issue, there is no scientific justification for herd reduction.

The forest health issue is addressed in the next Deer Management Series, No. 13.

 

 


 

 

 

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