Can controlled bow hunts reduce overabundant white-tailed deer populations in suburban ecosystems?

Abstract

In the northern suburbs of NYC, land managers have begun implementing bow-only hunts to reduce overabundant white-tailed deer (Odocoileus virginianus) herds in an effort to promote forest regeneration. However, there have been no attempts to model the impact of bow hunting on deer population growth. Using harvest statistics from the Mianus River Gorge Preserve in Westchester County, NY we simulated the impact of bow hunting on a population of female deer exhibiting density-dependent growth and explored a range of carrying capacities, immigration rates, and harvest intensities. Simulated bow hunting (adult harvest≥1.8femaleskm−2) was capable of achieving deer densities believed necessary for forest regeneration (2.9femaleskm−2) in closed populations where carrying capacity=13.8femaleskm−2, representing the lower end of deer overabundance. At this carrying capacity and low immigration rates, the impact of bow hunting was more variable, producing population declines ranging from 20 to 70% contingent on harvest rates. Hours per harvest increased rapidly as the deer population declined requiring nearly 5 times the hourly effort as female density approached target levels. Sustaining harvests over multiple decades, particularly as effort per deer harvest increases, is one of the biggest challenges facing bow-only hunts. As controlled bow hunts are executed by volunteer sportsmen, reductions will be determined by hunters’ capacity or willingness to increase effort and efficiency. Bow hunting will therefore likely result in deer densities lower than historical peak values, yet higher than is currently assumed necessary for forest regeneration.