Regional differences and long-term trends in lead exposure in mottled ducks

Abstract

We compared lead shot ingestion rates and bone lead levels in mottled ducks (Anas fulvigula maculosa) for regional differences and evaluated 16 years of lead shot ingestion data for evidence of decline. Gizzards (n=6,850) of hunter-killed mottled duck were collected from 1987–2002. The mean lead shot ingestion rate of mottled ducks from the Central Texas Coast and Upper Texas Coast was 7.32%±1.13% (SE) and 18.09%±1.55%, respectively. Lead shot ingestion rates declined gradually during the study period (P= 0.046). During the 1998–1999 hunting season, we examined lead concentrations in wing bones of 148 hunter-killed mottled ducks from the Central Texas, Upper Texas, and Southwest Louisiana coastal regions. Lead concentrations averaged 16.62 ppm±1.83 (SE) and did not differ among regions or age groups. Both lead shot ingestion rates and bone lead concentrations in mottled ducks remain high. Studies evaluating the effects of lead levels on mottled duck survival are needed.