Responses of Bachman's sparrows and prairie warblers to fragmentation

Fragmentation of a species’ habitat and the loss of habitat-patch connectivity have been a major factor in the decline of many species. Increased risks (e.g., predation, parasitism) that threaten population persistence are associated with the loss and fragmentation of large blocks of contiguous habitat for a species. Longleaf pine (Pinus palustris) savannas of the southeastern United States have experienced high rates of fragmentation and loss of connectivity. Consequently, they are home to many federally endangered and declining species across a wide variety of taxa. We examined the effects of fragmentation of pine savannas in southern Georgia for Bachman's sparrows (Peucaea aestivalis) and prairie warblers (Setophaga discolor) using translocation experiments and radio-telemetry (Bachman's sparrows only). Bachman's sparrows, a pine savanna specialist, showed lower probability of return within 48 hours when confronted with pine savannas fragmented by open fields, whereas prairie warblers were less sensitive to this type of landscape. Results from radio-telemetry indicated that Bachman's sparrows avoided open agricultural fields on their return paths and primarily used pine savanna edges instead. Efforts to reduce fragmentation of existing pine savannas in the Southeast will likely benefit vegetation specialists such as Bachman's sparrow but be of lesser benefit to vegetation generalists such as prairie warbler.