Influence of landscape composition on northern bobwhite population response to field border establishment

Abstract

ABSTRACTSince the 1960s, habitat loss resulting from cleaner farming, increased urbanization, and maturation of early successional cover has caused range‐wide decline of northern bobwhite (Colinus virginianus). Although field borders increase bobwhite habitat and increase local populations, understanding how the surrounding landscape influences bobwhite response to this management practice is critical to efficient implementation. We determined the relative influence of landscape composition and field border implementation on bobwhite densities and occupancy dynamics around crop fields in North Carolina and South Carolina, USA. We used 10‐minute distance point counts to estimate density, occupancy, colonization, and extinction rates of male bobwhite around 154 agriculture fields, half of which had a fallow field border. We estimated percent of cropland, forest, pasture, early successional, and urban cover within 1‐km radius buffers (314 ha) surrounding all point count locations. We examined the influence of 6 predictor variables (landscape composition metrics and field border presence) on bobwhite density and occupancy dynamics. Bobwhite density increased with the presence of field borders. Conversely, bobwhite density decreased as the percentage of urban, pasture, and forest lands increased. The presence of a field border did not influence occupancy, colonization, or extinction rates. However, as the percentage of cropland increased within the landscape, bobwhite occupancy increased and as the percentage of pasture increased, bobwhite colonization decreased. As the percentage of forest and urban increased and cropland decreased, bobwhite extinction rate increased. Our results indicated that local establishment of field borders does not increase bobwhite occupancy rates, but field borders can increase densities in suitable landscapes where bobwhite are present. Habitat restoration for bobwhite will most effectively increase population densities if focused in landscapes dominated by suitable cover types, where bobwhite occurrence is high. © 2013 The Wildlife Society.