| heavy metal and selenium levels in young cattle egrets from nesting colonies in the northeastern united states, puerto rico, and egypt. | colonially-nesting species of herons and egrets breed mainly in coastal areas, along rivers or near other large bodies of water. such areas are also preferred for human development, exposing nesting birds to various pollutants. from 1989-1991, the concentrations of heavy metals and selenium were studied in the feathers of fledgling cattle egrets bubulcus ibis, a terrestrially-feeding insectivore, from new york and delaware in the northeastern united states, from puerto rico, and from egypt. ther ... | 1992 | 1444587 |