Habitat Use by Postfledging American Black Ducks in Maine and New Brunswick

Abstract

We examined habitat use by 112 postfledging American black ducks (Anas rubripes) in eastern Maine and southwestern New Brunswick from September through early December of 1985, 1986, and 1987. Ducks were captured on Moosehorn National Wildlife Refuge (NWR), Maine. Palustrine Emergent Wetland was the most preferred habitat type. Riverine habitats were avoided in September, but were used more than, or in proportion to, their availability in November as ice formed on lentic habitats. Black ducks used a greater variety of habitat types during the day than at night, when ducks used mostly large (>30 ha) Emergent Wetland marshes. Managed impoundments of Moosehorn NWR were the most used wetlands (66% of all diurnal, 90% of all nocturnal locations). For black duck management, we propose maintaining large (30-50 ha) marshes containing dense emergent vegetation that are located near a complex of diverse wetland types. J. WILDL. MANAGE. 54(3):451-459 Habitat use by breeding American black ducks has been documented for northeastern North America (Coulter and Mendall 1968, Coulter and Miller 1968, Reed 1975, Ringelman 1980, Diefenbach 1988) and for mid-Atlantic saltmarshes (Stotts and Davis 1960). Most research on postbreeding ducks has involved adult birds during wing molt (Gilmer et al. 1977, Bowman 1987), whereas little is known of habitat use by young waterfowl after fledging. Data on habitat use by postfledging black ducks are lacking, and this period of the annual cycle might be critical to survival (Ringelman and Longcore 1980). Our objective was to describe daily and seasonal habitat use by postfledging black ducks. We thank field assistants B. E. Benedict, J. S. Henderson, R. A. Houston, J. D. Sayre, R. T. Speer, and D. B. Stotts. G. E. Horton, M. K. Meiman, and E. P. Schrading assisted with data entry. W. A. Halteman and S. M. Arthur provided statistical advice. D. G. Jorde and J. A. Spendelow reviewed the manuscript. Financial support was provided by the U.S. Fish and Wildlife Service through Cooperative Agreement No. 14-16-0009-1557, Research Work Order No. 2 with the University of Maine.