B.L. Mulhern T. W. Custer 1983 Aquatic birds may serve as indicators of regional metal contamination. Because the food of prefledgling herons (Nycticorax nycticorax ) comes only from areas near the colony, their tissues should reflect local metal contamination. The authors' hypothesis was that prefledgling herons from the Rhode Island colony should have higher concentrations of metals than do those from either the North Carolina or Massachusetts colonies. application/pdf 10.1007/BF01610118 en Springer link Heavy metal residues in prefledgling black-crowned night-herons from three Atlantic coast colonies article