Harlequins on the coast of Maine : 1994 progress report

Mittelhauser, Glen

'The harlequin duck is federally listed as a candidate species (C2) in the U.S. Federal Register, is listed as an endangered species in eastern Canada, and is currently a threatened species in Maine. The wintering population in Maine is estimated at 500 individuals and represents 50% of the estimated population in eastern North America. From the winters of 1988-89 to 1993-94, I periodically assessed harlequin distribution, population size, and population structure at Isle au Haut, an offshore island harboring roughly 15% of the wintering population in eastern North America. My objectives were to evaluate the distribution, population size, and population structure of harlequins wintering at Isle au Haut and study daily and hourly variation in harlequin numbers and distribution. During the winter of 1993-94, a total of eight shore-based surveys were conducted using methods identical to previous censuses. A total of 21 shore-based surveys have been conducted between January and March since 1988. Over the past six winters, a significant harlequin population decline has occurred at Isle au Haut with a roughly 15% drop in numbers over the period. Given the current eastern North American population estimate of fewer than 1000 individuals and considering this population is at or near minimum viable population size, continued population declines places it in danger of extinction. Annual surveys of population size and structure, habitat studies, and feeding biology studies should be initiated.' /STUDY LOCATIONS:/ /ISLE AU HAUT/ISLANDS/