R5 PM Avian Sentinels of Environmental Contamination
Thursday, 17 November 2005: 1:50 PM - 5:30 PM in 321-323

(GOL-1117-549200) The Tree Swallow (Tachycineta bicolor) and Osprey (Pandion haliaetus): A comparison of two widely used sentinel species of environmental contamination.

Golden, N¹, Custer, C², ¹ US Fish and Wildlife Service, Arlington, VA, USA² USGS Upper Midwest Environmental Science Center, La Crosse, WI, USA

ABSTRACT- The high trophic status of many terrestrial vertebrates makes them an important group of species for contaminant biomonitoring. Concentrations measured in tissues can reveal a toxicant's bioavailability and degree of accumulation in biota. Historically, large-scale monitoring of avian species has focused on those collected from hunting activities (e.g., waterfowl and game birds) or as a consequence of their abundance over a wide geographical area (e.g. starlings). However, site-specific research and management questions often call for a more refined choice of sentinels for ecotoxicological studies. The tree swallow (Tachycineta bicolor) and osprey (Pandion haliaetus) are two species whose behavioral and life history characteristics have rendered them particularly useful for monitoring contaminant exposure and effects in terrestrial vertebrates. The propensity of the swallow to nest in artificial boxes and its simple, well-defined food chain provide an avenue to assess the extent of contamination in a selected habitat, possible effects of those contaminants, and the degree of bioavailability to even higher level trophic feeders such as raptors. The swallow has been broadly utilized to assess site-specific contamination, determine the effects on exposed organisms, and develop biomarkers of exposure and effect for future monitoring efforts. The osprey, a piscivorous species with a high tendency to accumulate lipophilic chemicals, has been increasingly employed as an indicator of pollution in North American bays, rivers, and estuaries. The osprey is a widespread species that serves both as an accumulator of contaminants and as a species whose population has shown historic and well-studied sensitivity to contaminant insult. While both species represent upper-level consumers prone to bioaccumulation, differences in their exposure to and metabolism of toxicants can be important factors in choosing a proper sentinel for a particular study location, or may render them appropriate companion sentinels to more comprehensively examine environmental fate and effects of chemicals at a given site. The utility of each species for biomonitoring will be compared and contrasted.

Key words: biomonitoring, sentinel, osprey, tree swallow