Anatidae brood records in Maine during studies of Anas rubripes (American black duck), 1977–94

This report describes a compilation of brood observations for Anatidae species breeding in Maine during an 18-year period (1977–94) that were made by the U.S. Geological Survey’s Patuxent Wildlife Research Center while it was operated by the U.S. Fish and Wildlife Service. During four focused studies, variables affecting the declining Anas rubripes (Brewster, 1902) (American black duck, hereafter black duck) population were assessed. Broods were observed on seven geographical study sites within four study areas located in three of Maine’s five biophysical regions. For combined studies, 168 wetlands were monitored for broods.

The 1,907 recorded broods were distributed among study areas: 185 in Dixmont, 241 in Cherryfield and Beddington, 411 in Moosehorn, Baring Unit and Edmunds Unit, and 849 in Aroostook County, Agricultural and Forested sites. Additionally, 221 broods were recorded in the 117-hectare Downing Bog wetland at the Cherryfield site during annual evening visits made between 1985 and 1991. Twelve Anatidae species, mostly black duck (676), Aix sponsa (Linnaeus, 1758) (wood duck; 265), Aythya collaris (Donovan, 1809) (ring-necked duck; 246), and Lophodytes cucullatus (Linnaeus, 1758) (hooded merganser; 163) were observed. Only 139 broods of Anas platyrhynchos (Linnaeus, 1758) (mallard) were found; all but 9 broods were at the Aroostook County, Agricultural site. Branta canadensis (Linnaeus, 1758) (Canada goose) broods were found at the Aroostook County, Agricultural site (58) and Moosehorn, Baring Unit (97).

For the combined studies, 468 of 676 (69.2 percent) of black duck broods reached fledging age (Class IIc-III), whereas 93 of 139 (66.9 percent) of mallard broods reached fledging age. Black ducks used predominantly palustrine, emergent wetland; palustrine, forested wetland; and palustrine, scrub-shrub wetland. Of the 134 mallard broods observed at the Agricultural and Forested sites in Aroostook County, 130 (97.0 percent) were observed at the Agricultural site and 93 (71.5 percent) of them were recorded on two palustrine and two lacustrine, unconsolidated bottom class wetlands. Mean size of black duck, wood duck, and ring-necked duck broods in this report were similar to those reported from historic Maine data.