Population-level impacts of chemical contaminants on apex avian species

Abstract

We undertook short case studies of how (i) dieldrin and dichlorodiphenyltrichloroethane (DDT) affected populations of the peregrine falcon (Falco peregrinus) and other birds of prey in Britain and (ii) diclofenac impacted vulture populations across in south-east (SE) Asia. In both cases, high levels of (contaminated-mediated) acute mortality largely drove the population crashes and resulted in near extinctions of raptor species in several countries. Impaired, or naturally low, rates of reproduction likely limited recovery rates. The studies illustrate the huge, long-lived impacts that contaminants can have on bird populations. They changed our scientific understanding of the importance of different exposure routes and influenced how we now conduct monitoring and risk assessment. They also demonstrated the value of long-term population monitoring and archived specimens for identifying the causal factors and mechanisms behind the population crashes.