Harlequin Ducks (Histrionicus Histrionicus) in Maine, 1950–1999

Behavior and Diving of Harlequin Ducks Wintering at Isle au Haut, Maine

“…Coastal Maine supports the largest numbers of wintering Harlequin Ducks ( Histrionicus histrionicus ) in eastern North America (Mittelhauser 2000;Mittelhauser et al 2002), yet the foraging ecology of this species in Maine is poorly understood. Information on foraging can be important in identifying factors critical to survival during winter conditions (Nilsson 1970;Paulus 1988), which are often harsh in the Northwest Atlantic.…”

“…2002), feeding behavior and foraging patterns are not necessarily the same throughout a species range because of differing habitat, prey species and availability, and environmental conditions (Nilsson 1970;Paulus 1988;Mittelhauser 2000;Rodway and Cooke 2002). From 125 to 250 Harlequin Ducks wintered at Isle au Haut, Maine in the 1990s (Mittelhauser 2000;Mittelhauser et al . 2002).…”

Population trends and habitat use of Harlequin Ducks in Rhode Island

“…Declines in the number of Harlequin Ducks along the Atlantic Coast were attributed to factors such as habitat loss, oil contamination, climatic and stream level changes, and hunting (Thomas and Robert 2001). Of these, heavy hunting pressure in eastern North America has been hypothesized to be the primary factor causing population declines because Harlequin Ducks were targeted for their ease of hunting and the brightly colored plumage of males (Vickery 1988, Goudie 1989, Mittelhauser et al 2002). Their decline and scarcity led the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) to designate Harlequin Ducks as endangered in 1990 (Thomas and Robert 2001).…”

“…The population of Harlequin Ducks in Rhode Island increased from 1976 to 2004, whereas populations in Atlantic Canada and Maine experienced declines until about 1992 before increasing in subsequent years (Mittelhauser 2000, Thomas and Robert 2001, Mittelhauser et al 2002). Although the population in Rhode Island was smaller in the 1970s and 1980s than today, population trends in southern New England apparently did not reflect the decline experienced further north.…”

“…Our results suggest that the hunting moratorium has resulted in changes in the sex ratio of local populations, with the Rhode Island population now exhibiting a male‐biased ratio similar to larger populations of Harlequin Ducks in the Pacific (i.e., 1.51:1 in British Columbia; Rodway et al 2003). Considering that Harlequin Ducks in the Pacific do not exhibit latitudinal sexual segregation (Rodway et al 2003) and that the proportion of males in Maine increased to 55% (1.2:1) in 1996 (Mittelhauser et al 2002), male‐biased sex ratios in Rhode Island might be representative of population recovery in other areas along the Atlantic Coast.…”