Impact of Reconstructed Wetlands on the Tree Swallow (Tachycineta bicolor)

Abstract

Tree swallow (Tachycineta bicolor) nestlings were used as a sentinel species to evaluate the bioavailability and effect of contaminants to terrestrial life at reconstructed wetlands, Kingman Lake and Kenilworth Marsh, on the Anacostia River. Nesting success, survival, growth and developmental parameters were recorded and compared to an established reference location. Metals, metalloids and organic contaminant concentrations in the eggs and nestlings were examined. In addition, biomarkers of exposure for some organic contaminants (cytochrome P450), some pesticides (cholinesterase activity), and lead (delta-aminolevulinic acid dehydratase) were measured. Only subtle differences between sites were observed for reproductive and growth parameters of the nestlings. Chemical analysis showed significant differences (p<0.05) between sites of relatively few contaminants. Of the biomarkers examined, only cytochrome P450 activity was found to be significantly different between sites (p=0.04). Contaminant concentrations and biomarker data from the tree swallows suggest no serious impacts to insectivorous birds residing in these wetlands.