Environmental contaminants in redheads wintering in coastal Louisiana and Texas

Whole body and liver analyses indicated that wintering redheads (Aythya americana; n = 70) in coastal Louisiana (one site) and Texas (two sites) were relatively free of contamination with common trace elements, organochlorines, and hydrocarbons. Most trace elements, including As, Cr, Hg, Mg, Mn, Ni, Pb, Se, Sr, and Zn, were within background concentrations in livers; levels of B, Cd, Cu, and Fe were elevated in some specimens. Only one organochlorine, DDE, was detected in redhead carcasses, but its concentration was below reported toxic levels in waterfowl. Body burdens of aliphatic and aromatic hydrocarbons were generally low, but levels of pristane, total hydrocarbons, and the ratios of phytane:n-octadecane and pristane:n-heptadecane were indicative of possible chronic exposure to petroleum. Based on brain cholinesterase assays, redheads were not recently exposed to organophosphorous or carbamate pesticides. Of 30 elements or compounds tested for seasonal differences, only Se increased from early to late winter at one of the three sites. Eight of 57 contaminants differed among the three sites; no sex or age differences were found.