White-tailed Deer on a Barrier Island: Implications for Preserving an Ecologically Important Maritime Forest

The white-tailed deer (Odocoileus virginianus) population on Bald Head Island has increased, threatening a unique maritime forest in southeastern North Carolina. Bald Head Island is ~620 ha and is characterized by live oak (Quercus virginiana) maritime forest, dunes, tidal marsh, and urban development. Preservation of maritime forest is important for barrier island conservation. Maritime forests are important coastal habitats that are under significant threat from development, and in the absence of reproductive controls, white-tailed deer can negatively impact ecosystems through over-browsing. Therefore, our objectives were to determine emigration, home range, cover type use and selection, and population density of whitetailed deer on Bald Head Island to provide baseline information which could impact deer management decisions. From 5 January through 31 March 2008 and 2 January through 31 January 2009, 12 females and one male were chemically immobilized and equipped with VHF radiocollars. From January 2008 through January 2010, a minimum of four visual locations were obtained per animal per month. We used a fixed kernel density estimator to calculate 90% (home range) and 50% (core area) utilization contours for radiocollared female deer (n = 11). To determine cover type use and selection, we used land cover data generated by the Southeast Gap Analysis Project and a chi-square (χ2) goodness-of fit test to determine differences between expected and observed use of cover types within home ranges. Significance levels for 95% confidence intervals were determined using the Bonferroni method. From May through August 2008 and 2009, spotlight surveys were conducted and used to generate population estimates with a Lincoln- Peterson index. No radiocollared white-tailed deer migrated from Bald Head Island during the course of the study and average home range and core areas were 60.73 ha (SE = 5.63) and 15.00 ha (SE = 1.37), respectively. Maritime forest/shrub comprised ~275 ha (44%) of available habitat on Bald Head Island and were used by radiocollared deer at levels greater than available, whereas dune/grasslands were used less than available. All other cover types were used in proportion to availability. Population densities of white-tailed deer were ~17 and ~15 deer/km2 for 2008 and 2009, respectively. Based on home range size and cover type selection, and until additional research is conducted, we recommend that white-tailed deer populations be managed at current levels to prevent degradation of important maritime forest habitat.

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