METAL ACCUMULATION AND METALLOTHIONEIN CONCENTRATIONS IN TREE SWALLOWNESTLINGS NEAR ACIDIFIED LAKES

We studied metal accumulation in hepatic and renal tissues of tree swa llow (Tachycineta bicolor) nestlings at acidified and nonacid referenc e lakes in northwestern Ontario. Hepatic concentrations of metallothio nein (metal-binding proteins, MT) in tree swallow nestlings were negat ively correlated with pH of the nest-site take. Combined concentration s of Cu and Zn in the liver were correlated with liver MT concentratio ns, but Cd was not. Although no overt signs of metal toxicity were obs erved in nestlings near acid lakes, our results clearly provided evide nce that metals are transferred from acid lakes to birds and that thes e metals are correlated with increases in hepatic MT production.