Avian response to plant community composition and structure in regenerating timber harvests protected by ungulate exclusion fencing

Forests of eastern North America have been negatively impacted by excessive white-tailed deer browsing for decades. Previous studies have shown how deer-driven changes to forest structure, plant species composition, and microhabitat negatively impact forest birds. However, most experimental studies used relatively small plot sizes with few replications, limiting the transferability of findings to operational-scale timber harvests and landscape-scale management. We studied the influence of white-tailed deer browsing on breeding bird communities in ten pairs of operational-sized fenced and unfenced regeneration timber harvests in northcentral Pennsylvania. Based on a previous study that examined correlations between bird and deer abundance in Pennsylvania, we developed species-specific predictions about how density would vary between fenced and unfenced harvests. We predicted six species would show a negative response to deer and three would show a neutral response. Overall, diversity and composition of breeding bird communities did not differ between fenced and unfenced harvests. However, four species showed a negative response to deer, four showed a neutral response to deer, and one showed a positive response to deer. Thus, six of nine focal species aligned with our predictions: Negative (n = 4) and neutral (n = 2). Densities of two remaining focal species were associated with vegetative features that also were consistent with our predictions. Our final focal species showed a strong positive association with unfenced harvests, contrary to our prediction. Our findings demonstrate that deer-induced impacts on vegetation in operational-scale timber harvests can have considerable influence on densities of some avian species. We conclude that the use of deer-exclusion fencing after timber harvests is an effective and sometimes necessary management tool to achieve maximum forestry and wildlife benefits.