Impact of hunting pressure on adult male white-tailed deer behavior

Abstract

The impact of hunting pressure on white-tailed deer behavior has been broadly studied, but specific examination of the interaction between adult males and hunters has not been conducted using global positioning system (GPS) technology. During 2006-2007 at Chesapeake Farms, a privately owned property in Kent County, Maryland, research focused on this interaction using GPS collars affixed to 19 adult male white-tailed deer. I looked for changes in home range and core area size, shifts in home range and core area, movement, activity, vulnerability, and refuge use using an analysis of variance (ANOVA) and Tukey’s honestly significant difference (HSD) test. Movement decreased during the dawn (F = 6.284, df = 24, P = 0.006) and day (F = 11.060, df = 24, P < 0.001) hours, and activity decreased during the day (F = 6.289, df = 24, P = 0.006). However, no other significant findings provided evidence that these changes were solely a function of Maryland’s 2-week hunting season and not a by-product of temporal correlation with decreases in male activity that would be expected during the post-breed season. I concluded that hunters on Chesapeake Farms did not exert sufficient hunting pressure to induce noticeable behavioral change in adult male white-tailed deer. Combining data gathered from the GPS-collared adult males with a previous study (Tomberlin 2007), I analyzed adult male excursions outside of their home range during the fall and winter months. Documenting 30 excursions, the majority of adult males (53%) engaged in at least one excursion during study periods. Twenty-two excursions (73%) were made during the pre-breed 2 or breeding periods, and breeding-season related motives seemed to be the driving force behind most adult male excursions. By comparing excursions during hunting season with known hunter locations, it is not likely that hunting was an instigating factor for excursions at Chesapeake Farms. In addition to the GPS collar research, a catch-per-unit-effort (CPUE) estimator was improved by converting FORTRAN code (Bishir et al. 1996) to JMP scripting language (JSL). The method was validated by comparing previous (1981-1991) FORTRAN estimates of the antlered male population at Chesapeake Farms, MD, to JMP estimates. Also, I tested the CPUE-JMP estimator’s effectiveness with regards to varying length hunting seasons and traditional versus quality deer management (QDM) paradigms. The new method improved estimates by 25%, and different season lengths and deer management regimes did not have a significant impact on estimates. Long-term trends produced by the CPUE-JMP estimator were sufficient for most harvested big-game population management applications. Lastly, I examined the natural mortality factor of intracranial abscessation in the adult male white-tailed deer population at Chesapeake Farms, MD. From 2003-2007, mortality was documented for and necropsies performed on 26 GPS-collared adult males. Adult male mortality due to intracranial abscessation was disproportionately high (35%) compared to the national average (9%), and if additive to other natural mortality factors and hunter harvests in the population could pose a serious obstacle to achievement of QDM objectives.