Breeding Ecology at Tamarac National Wildlife Refuge, Minnesota
University of Minnesota
Tamarac NWR is the westernmost study site in the US with ~1000 breeding Golden-winged Warblers (1-2% of the global population). It has a variety of early-successional habitats. We initiated our work here as it was a high-density population and thought to be likely one of the last locations to be influenced by Blue-winged Warblers. Our study has focused on breeding density and reproductive performance of Golden-winged Warblers in the presumed absence of Blue-winged Warblers. In two intensive study areas, we spot mapped territorial males as well as located and monitored nests. We subsequently assessed the habitat composition and structure within the territories and at nest sites. We also captured, banded, and collected blood samples from adults on the breeding territories.
Preliminary results demonstrate very high reproductive success within territories that averaged 0.9 territories / ha. We capture 53 birds for genetic analyses in 2009 and limited evidence of BWWA introgression was observed. Moreover, a Blue-winged Warbler was captured in 2010, although it is uncertain if it paired and produced young.
Funding for the project has been provided by the National Fish and Wildlife Foundation via the Golden-winged Warbler Working Group, the University of Minnesota, U of M’s Undergraduate Research Opportunities Program, and Tamarac National Wildlife Refuge.