Detecting Trumpeter Swans Harvested in Tundra Swan Hunts

Identifying the less numerous trumpeter swans (Cygnus buccinator) harvested in tundra swan (C. columbianus) hunts is a management concern. As trumpeter swan ranges expand, their populations become more sympatric with tundra swans during fall and winter, but the 2 species are difficult to separate in the field. Eight states currently allow limited permit hunting for tundra swans. The hunting of trumpeter swans is currently limited by experimental quota to 3 states in the Pacific Flyway. We compared bill measurements (tip to posterior edge of nares opening) for trumpeter swans captured in Idaho (n=672) with measurements of tundra swans harvested in Utah (n=1,414) and with measurements reported on postcards (n=890) returned by hunters who harvested swans in Montana. Mean bill measurements for adult and cygnet trumpeter swans were 68.8 mm and 67.6 mm, respectively, and for tundra swans, 54.0 mm and 52.4 mm, respectively; differences were significant (P