Bioaccumulation of Heavy Metals in Robins - Proposed Pollution Sources & Pathways

Lead pollution remains a prevalent problem in urban soils, posing health risks for humans and wildlife alike, but the pathways leading to disease are poorly understood. This pilot study sought to characterize lead concentration trends in American Robins and identify potential pathways of lead uptake. A sample set (n=55) of American Robins from Bloomington, IN were analyzed for heavy metal content in blood samples, with a particular focus on lead. Robins were profiled based on sex, estimated fat content, wingspan, weight, and capture location. Initial ICP-MS results revealed a wide breadth of blood lead concentrations ranging from 0.85-19.4 μg/dL. Lead concentrations showed no relationship with bird sex, wingspan, or location but there may be a relationship with estimated fat content. While no birds displayed blood lead levels indicative of lead toxicity accepted by the veterinarian community, increasing evidence suggests lead toxicity is better understood through a spectrum model rather than a categorical model. Thus, the extent of elevated lead observed in American Robins raises concern for urban lead pollution and potential lead toxicity effects magnifying through the food chain. Initial studies indicate elevated lead concentrations can be present in urban soils, providing a likely pathway of lead bioaccumulation through soil-eating worms, which also displayed elevated lead levels. Outcomes of this initial research warrant further work towards the development of a more robust model of lead sourcing and the extent to which lead is impacting urban wildlife.