Abstract
Feathers have been widely used to assess mercury contamination in birds as they reflect metal concentrations accumulated between successive moult periods: they are also easy to sample and have minimum impact on the study birds. Moult is considered the major pathway for mercury excretion in seabirds. Penguins are widely believed to undergo a complete, annual moult during which they do not feed. As penguins lose all their feathers, they are expected to have a low individual-variability in feather mercury concentration as all feathers are formed simultaneously from the same somatic reserves. This assumption is central to penguin studies that use feathers to examine the annual or among-individual variation in mercury concentrations in penguins. To test this assumption, we measured the mercury concentrations in 3–5 body feathers of 52 gentoo penguins (Pygoscelis papua) breeding at Bird Island, South Georgia (54°S 38°W). Twenty-five percent of the penguins studied showed substantial within-individual variation in the amount of mercury in their feathers (Coefficient of Variation: 34.7–96.7%). This variation may be caused by differences in moult patterns among individuals within the population leading to different interpretations in the overall population. Further investigation is now needed to fully understand individual variation in penguins’ moult.
Highlights
The increasing concentration of contaminants in the environment and the need to understand their effects on wildlife are some of the main reasons for the development of bio monitoring programs [1]
This project was approved by the Animal Ethics Committee of British Antarctic Survey (BAS) and under a permit issued by the Government of South Georgia
Mercury concentrations in the population ranged from 0.15–3.10 mg kg-1
Summary
The increasing concentration of contaminants in the environment and the need to understand their effects on wildlife are some of the main reasons for the development of bio monitoring programs [1]. Many seabird species are considered at risk and in need of protection as they face many and diverse threats in their natural habitat [4] This fact reinforces the need to collect more information and to use non-invasive methods in defined monitoring programs [5]. The use of birds with a synchronous moult, such as penguins and seabird fledglings, has been recommended as suitable for monitoring contaminants in seabird communities [17] This is because of their synchronous moult that can be defined as a moult in which all body feathers grow simultaneously, at a constant rate and in a short period of time. Our aims for this study were 1) to assess if there was within-individual variability in the mercury content of body feathers from gentoo penguins; 2) to evaluate the causes of such variability given the assumed synchronous moulting pattern; and 3) to discuss future studies that should be performed to clarify the occurrence of variation in penguins’ moult
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