LEAD CONTAMINATION OF WATERFOWL IN TASMANIA BY INGESTION OF SHOTGUN PELLETS FROM DUCK SHOOTING

Shallow-water sediments in duck-shooting areas were sampled to assess availability of shot pellets to foraging waterbirds by determining pel let densities and relating settlement behaviour to particle size compo sition. Sediments dominated by smaller particle sizes were found to in hibit pellet settlement below the surface layer. Blood samples were ob tained from black swans (Cygnus atrata) and more than 17% had elevated lead concentrations. A small number of gizzards from Pacific black du cks (Anas superciliosa) held no pellets, but approximately 50% of live rs and bones examined showed elevated lead concentrations. Alternative sources of lead pollution were considered and water and sediment samp ling was carried out near the closest highway, but lead concentrations were very low. The lead residues found in birds, and pellet densities in sediments, were broadly similar to those reported for areas with d ocumented lead pellet contamination problems outside Tasmania. This in dicates the existence of a lead pellet problem requiring remedial acti on. Options for this are briefly considered, as is the likelihood of o ther species being contaminated by direct ingestion of pellets, or ind irectly by predation.