Effects of nesting location on stress metrics in blood in American Eiders
LE3 .A278 2014
Bachelor of Science
The Common Eider, Somateria mollissima population in Nova Scotia is in decline. There have been several factors that have been proposed as contributing to this decline, and some of these may manifest themselves in the birds through increased physiological stress, which in turn might reduce reproductive success. Comparing heterophil: lymphocyte (H:L) ratios is a common method of evaluating long-‐term stress levels in avian species. My project contrasted stress levels, as indicated by H:L ratios, of eiders nesting in exposed habitats (e.g., tall grass) with eiders nesting in sheltered habitats (e.g., overturned , half plastic barrels). If increased susceptibility to avian predation increased breeding stress, we expected to see higher H:L ratios for eiders nesting in exposed habitat and lower H:L ratios in sheltered habitat. We extracted blood from breeding females nesting in the Eastern Shore Islands (sheltered), Bon Portage Island (exposed), and John’s Island (exposed), and blood smears were prepared. I performed leukocyte counts on the blood smears and the H:L ratios were determined. Mean H:L ratios of eiders from John’s Island were higher than those from either Bon Portage Island or the Eastern Shore Islands, but these differences were not quite statistically significant. Interestingly, John’s Island has livestock and may have coyotes on it, while the other sites do not. Comparing my data to values established internationally, I found that eiders in the Canadian Arctic had significantly higher baseline H:L ratios than those from Nova Scotia, which in turn were higher than those of breeding birds in Iceland. I postulate that these differences may be related to their typical, annual environment.
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