Tissues of greater scaup (Aythya marila mariloides) and components of their habitat (sediment, plankton, macroalgae, and invertebrates) were collected for heavy metal analysis in the winter of 1996-97 from US Department of the Interior wildlife refuges in the Long Island region. Geographic and temporal relationships between the concentration of nine metals in tissue and in habitat components were examined. In greater scaup tissues and habitat components, concentrations of As and Se were highest in Branford, Connecticut; Pb values were greatest in Oyster Bay, New York; and Hg concentrations were largest in Sandy Hook, New Jersey. Over the course of the winter, the concentration of Hg in liver increased, and concentrations of Cd, Cr, Cu, Hg, Pb, Se, and Zn in kidney decreased. Based on several criteria derived from geographic and temporal trends, metals were ranked using the apparent biomonitoring efficacy of greater scaup (As = Cr > Cu = Pb = Zn = Hg > Se = Cd > Ni). Although the seasonal migration and daily mobility of greater scaup are drawbacks to using this species as a sentinel for metal pollution, it was possible to demonstrate a relationship between geographic and temporal patterns of metals in habitat and greater scaup tissue. However, most metal concentrations in tissue were below thresholds known to adversely affect health of waterfowl.