An evaluation of population estimators and forage availability and nutritional quality for white-tailed deer in Tennessee

Given the white-tailed deer’s (Odocoileus virginianus; deer) popularity and potentially negative impact on forested systems; Arnold Air Force Base (AAFB) in Tullahoma, Tennessee, USA has made minimizing negative deer impacts on biodiversity a priority. To address these management issues, I initiated a study on AAFB to investigate deer survey techniques and the effects of deer density on forage availability across vegetative communities.

Current use of infrared-triggered cameras (camera) for estimating deer populations does not provide a measure of precision critical for density estimation. I conducted a camera survey for deer in Wildlife Management Area (WMA) Units 1 and 2 at AAFB, August 2010 and used Program DENSITY to fit a spatial detection function of capture-recapture (spatial modeling) data from the camera surveys of bucks. Spatial modeling can provide reliable estimates of buck density and facilitate our understanding of biases associated with camera surveys for deer.

I compared population and precision estimates from spotlight, ground thermal infrared imaging (ground imaging), and aerial vertical-looking infrared (aerial imaging) surveys in the Security Area (SA) of AAFB, January–February 2010. All 3 techniques provided a precise estimate of deer density. However, the high cost of ground imaging does not justify its use. I also found the potential of road bias in distance sampling to invalidate the technique, unless random transects representative of the study area can be applied. Aerial imaging is less susceptible to road bias, but use should be restricted to large areas where high cost can be justified.

I evaluated the effects of 2 deer densities on forage availability and quality within 4 vegetative communities on WMA Units 1 and 2, and the SA of AAFB 2010. Forage availability was consistently greater during summer verses winter and within middle-aged and young pine stands at the low deer density site versus the high deer density site. Both crude protein and total digestible nutrient values were similar regardless of deer density. I recommend managers consider implementing management practices that would reduce deer density and increase forage availability when forage availability beings to decline and deer density estimates approach levels seen detrimental in literature.