LE3 .A278 1999

1999

Taylor, Phil

Acadia University

Master of Science

Masters

Biology

Biology

Mercury is a global pollutant that negatively impacts visual function, breeding behaviour, and development of animals. Common loons (Gavia immer) are high trophic level, visually oriented predators suggested to be sensitive to mercury (Hg) contamination. Previous studies have shown that exposure to Hg in prey is associated with changes in pre-nesting adult loon behaviour. Loons in Kejimkujik National Park (Nova Scotia, Canada) have the highest blood Hg concentrations of any loon population tested. I monitored the summer behaviour of loons in Kejimkujik and the Lepreau watershed (New Brunswick, Canada) to test the hypothesis that high Hg levels in Kejimkujik are associated with negative behavioural impacts. The amount of time that chicks spend brooding (by back-riding) decreases as Hg levels in their blood rise and preening increases. The concomitant increase in energy expenditure is not compensated with increases in feeding rates or begging. More frequent back-riding is associated with improved fledging success. Adult behaviour and hunting patterns appeared to be affected by Hg, but not significantly so. I also show that time activity budgets of very young chicks indicate effects of Hg concentrations in their blood. However, the behaviour of breeding and non-breeding adults is not a sensitive indicator of in situ contamination levels. I confirm the hypothesis that loons and other upper-trophic level predators could be at risk from elevated levels of bioavailable Hg. This may help explain the chronically low productivity of contaminated sites such as Kejimkujik, and allow for more focused management initiatives.

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