Assessing the Value of Department of Defense Lands in Alaska to a Declining Species, the Rusty Blackbird

Abstract

Abstract : The Rusty Blackbird (Euphagus carolinus) has suffered one of the steepest declines of any bird species in North America with populations reduced by 90-98% since 1966. Despite this steep decline, the species' breeding habitat requirements and nesting ecology have remained poorly studied. In this study we evaluated the value of military installations in Alaska to breeding Rusty Blackbirds in terms of providing breeding habitats associated with high breeding occurrence, nest abundance, and reproductive success, and low incidence of disease and contaminants. Sampled sites included Elmendorf Air Force Base and Fort Richardson near Anchorage (Anchorage) and the Tanana Flats Training Area of Fort Wainwright (Tanana Flats). Because the species has not been the focus of breeding surveys outside of New England, we also evaluated methods for determining site occupancy and nest abundance in these very different wetland landscapes in Alaska, Anchorage with isolated and well defined wetland bodies within a primarily upland landscape; the Tanana Flats with a mosaic of poorly differentiated wetlands in the floodplain of the Tanana River. Military installations in this study clearly provided important breeding habitats for Rusty Blackbirds. This was evidenced by high breeding site occupancy rates both in Anchorage (51%) and Tanana Flats (91%); much higher than we expected based on previous general avian surveys conducted in these study areas. The particularly high occupancy rate on the Tanana Flats highlights how this training area provides prime breeding habitat for this species. Most sites with appropriate habitat were used by breeding birds in both study areas. This indicates that the widespread declines in this species have not yet resulted in local extirpations of this species from suitable breeding habitats on these military sites.