Contaminants in lesser and greater scaup staging on the lower Great Lakes.

The decrease and subsequent lack of recovery of the North American scaup population has increased concerns about contaminants acquired during migration. We collected 189 fall- and spring-migrant lesser (Aythya affinis) and greater scaup (A. marila) on the lower Great Lakes (LGL) to determine if organic contaminants and trace elements in scaup livers were increased and to evaluate sources of variation in selenium (Se) burdens. We found that all organic contaminants were below toxic levels. Of 18 trace elements, only Se was detected at increased (>10-ppm dry-mass) levels. Se in lesser scaup increased but remained constant in greater scaup throughout fall; levels were increased in 14% of lesser scaup and 46% of greater scaup. During spring, Se increased in lesser scaup but decreased slightly in greater scaup; levels were increased in 75% of lesser scaup and 93% of greater scaup. We suggest that Se may be problematic for some breeding female scaup after departing the LGL, but more research is needed to determine the extent to which it affects scaup demographics.