Many Nearctic-Neotropic migrant songbirds are experiencing long-term population declines in North America due in part to habitat fragmentation on the breeding grounds. However, bird responses to landscape-level complexity in the form of natural heterogeneity compared to habitat fragmentation is not well established. In addition, little research has been conducted that links the landscape level and also habitat and vegetation levels to multiple bird responses, such as species richness, individual abundance, and behavior. To accomplish this goal, we surveyed specific migratory birds at three edge types (residential edge, agricultural edge, and natural edge) to determine abundance and richness of songbirds in forest-edge habitats. Focal species for this study were Eastern Kingbird (Tyrannus tyrannus), Great Crested Flycatcher (Myiarchus crinitus), Red-eyed Vireo (Vireo olivaceus), Warbling Vireo (Vireo gilvus), Gray Catbird (Dumetella carolinensis), Yellow Warbler (Setophaga petechia), Common Yellowthroat (Geothlypis trichas), and Baltimore Oriole (Icterus galbula). In addition, we compared singing behavior for Common Yellowthroat, Warbling Vireo, Baltimore Oriole, and Yellow Warbler to establish if this more subtle measure is affected by edge type. Finally, we compared bird and song measures to landscape-level fragmentation and heterogeneity metrics to determine the scales at which these species respond. Four species responded to habitat categories, all more abundant at natural edges with greater wetland cover. In addition, all species except Eastern Kingbird responded differentially to fragmentation and heterogeneity at the landscape scale. Song rates for Common Yellowthroat, Baltimore Oriole, and Warbling Vireo also responded to landscape variables, a scale that has not been considered previously in other research. Information from this study will be valuable to elucidate differences among species and habitats during the breeding season to help in overall conservation of important songbirds in New England.
Program Report: Landscape effects on habitat use and singing behavior by edge-breeding bird species in Massachusetts
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