Although feathers are commonly used to monitor mercury in birds, their reliability has not been assessed for many avian species, including most songbirds.
Researchers wanted to better understand the relationships between total mercury concentrations in feathers and other tissues for songbirds in the thrush and sparrow families. They observed high variation within feathers of some individuals, suggesting that estimates of mercury exposure could vary depending on which feather was sampled. They also found that the feathers were low to moderately successful in predicting total mercury concentrations of individual birds. Alternatively, nail samples better predicted internal tissue mercury concentrations in both thrushes and sparrows; however, authors point out that collecting big enough nail samples could harm living birds, particularly small songbirds. Results suggest that, despite their current use in the literature, feathers may not be the most suitable sampling matrix for mercury monitoring in some songbird species.
Low, K.E., Ramsden, D.K., Jackson, A.K., Emery, C.S., Robinson, W.D., Randolph, J., Eagles-Smith, C.A., 2019, Songbird feathers as indicators of mercury exposure- high variability and low predictive power suggest limitations: Ecotoxicology, https://doi.org/10.1007/s10646-019-02052-y