Comparison of feather mercury concentrations in live-caught vs. found-dead chick carcasses of Gentoo Penguins (Pygoscelis papua)

There is limited direct empirical evidence to evaluate the efficacy of using opportunistically found bird carcasses as proxies for estimating pollutant exposure in populations of live birds for avian ecotoxicology studies. In this study, we analyzed total mercury concentrations in feathers collected from live Gentoo Penguin (Pygoscelis papua) chicks and from Gentoo Penguin chick carcasses found at the same breeding colonies. Distributions of mercury concentrations for feathers from live-caught chicks and from found-dead chicks broadly overlap and, for our study, feathers from found-dead penguin chicks provide similar information about exposure to mercury as do feathers from live penguin chicks from the same locations. Our results suggest that, when mercury is estimated to be below adverse effect levels, the common practice of sampling from opportunistically found chick carcasses is a suitable and less-invasive alternative method of specimen collection in penguin colonies.