Winter use of early successional habitats by birds within the Alligator River, NWR and Pocosin Lakes, NWR: Evaluating the benefit of management scenarios
Abstract
Many bird species that require early successional habitats have declined dramatically throughout the Northeastern United States during the past four decades. Several of these species are temperate migrants that spend the winter months in the southeastern United States. Refuge lands that contain early successional habitats may play an important role in the life cycle of these species. Understanding the requirements of target species is a critical first step toward integrating these species into future conservation plans. The primary objective of this study was to investigate the community of avian species utilizing early successional habitats within Alligator River, NWR and Pocosin Lakes, NWR during the winter months. A secondary objective was to evaluate the benefit of alternative management scenarios. Fifty-four 500 m transects were established and surveyed three times for birds from January through March of 2002. Survey results were used to derive habitat-specific density estimates for 9 cover types. Density estimates were used along with a habitat inventory of Alligator River, NWR to generate population projections. The influence of various management scenarios on the number of birds supported was evaluated by shifting the allocation of cover types and recalculating population projections based on the new conditions. The farm unit within Alligator River, NWR currently supports an estimated 24,000 birds. The establishment of fallow filter strips under the Conservation Reserve Program appears to be a benchmark event for the winter bird community. The community has two dominant divisions including species that utilize grasslands and species that require bare ground. Population projections suggest that a shift in management to discourage the formation of dense forb stands within filter strips could more than double the number of birds supported within upland areas. More modest gains could also be achieved by altering management of active agricultural areas and moist soil units. For the latter, prioritization of target species will be required to allow for the develop a goal-oriented management program. Study areas within Pocosin Lakes, NWR supported a community of birds that was dominated by frugivores. The large standing crop of fruit supported by the vast tall pocosins across the refuge and broader peninsula likely has regional significance to temperate migrants that depend on fruit for the winter. These habitats may support very large portions of populations from throughout the Northeast. The strategic value of these habitats to birds during both migration and winter requires further evaluation.
