SURVIVAL RATES AND BLOOD METAL CONCENTRATIONS IN TWO SPECIES OF FREE-RANGING NORTH AMERICAN SEA DUCKS

摘要: Populations of several species North American sea ducks have declined in the past few decades. Exposure to environmental contaminants, particularly metals, has been proposed as one many possible factors contributing these declines. Population dynamics are influenced by survival rates and breeding effort. In present study, we examined relationships between blood metal concentrations (Cd, Pb, Se, Hg) apparent annual recapture probabilities (the latter a surrogate for effort) adult females two duck species, king eider (Somateria spectabilis) white-winged scoter (Melanitta fusca), both which experienced declines continental population during recent years. No support was found hypothesis that exposure scoters metals or eiders Cd, Pb adversely affected survival. We detected weak negative relationship (beta = -0.833) Hg eiders, but 90% confidence interval slope estimate overlapped zero (-2.439 +0.672). Recapture were unrelated either species. Evidence indicated probability -194.77; interval, -203.770 -185.778). Mercury levels low samples may not adequately represent long-term Hg. Therefore, conclusions regarding effects on birds should be considered with caution.