Breeding ecology of harlequin ducks in Prince William Sound, Alaska

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Breeding habitat and productivity of harlequin ducks was studied in eastern Prince William Sound (EPWS), Alaska, during 1991–1993. Harlequin ducks usually selected the largest anadromous salmon streams available for nesting. Volume discharge of breeding streams averaged 3.2 m3/s and was the strongest variable distinguishing between streams used and not used by breeding harlequins. Ten nests of harlequins were located on southwest-facing, steeply-sloped banks of first order tributaries near timberline elevations. Nests were associated with woody debris and shrubs, in shallow depressions or cavities, and beneath the canopy of old growth forest. Productivity of harlequin ducks in EPWS was low relative to other breeding populations. Nest density for 7 streams was approximately 0.3–0.5 breeding females per km. Estimated breeding propensity of adult females was 86% in 1991 and 74% in 1992. Average clutch size for 8 nests was 6.1 eggs. Duckling mortality was estimated at 59%, occurring mostly during 15–35 days of age. Average brood size at fledging was 2.50, and recruitment was estimated at 0.6–1.1 per breeding female. Coastline densities of broods during 1991–1993, respectively, was 2.3, 0.9, and 1.8 per 100 km.

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ELECTRONIC FILE - Zoology: Birds

SWAP (2/19/2016) citation:
Crowley DW, Patten SM Jr. 1996. Breeding ecology of harlequin ducks in Prince William Sound, Alaska. Final report. Anchorage (AK): Alaska Department of Fish and Game, Division of Wildlife Conservation. 83 p. Restoration Study No. 71. [accessed 2015 Jun 1]. http://www.evostc.state.ak.us/Store/FinalReports/1992-R071-Final.pdf.