Mercury in Songbirds Breeding at Denali National Park

A white-crowned sparrow. NPS.

Why study it

Songbirds (passerines) seem more sensitive to mercury than other groups of birds, yet little is known about mercury in songbirds that breed at high latitudes.

The study

This preliminary study measured total mercury in 343 feathers from 12 species of migratory songbirds breeding in Denali National Park and Preserve, in subarctic interior Alaska, collected from 2015 to 2017. Feather mercury reflects exposure while the feather grew — assumed to be mostly on the breeding grounds.

Findings

• Concentrations ranged from near zero to 6.34 μg/g.
• Most species had relatively low mercury, but some individual birds had enough to face harmful physiological and behavioral effects.
• Diet may matter: species that don't eat mainly insects and other invertebrates tended toward lower mercury.
• Overall, exposure was low for songbirds breeding in the subarctic. More study would clarify exposure and ecology in this little-studied region.

Sources

Based on "Songbird Exposure to Mercury," Denali National Park and Preserve, National Park Service, summarizing I. J. Stenhouse, E. M. Adams, L. M. Phillips, S. Weidensaul and C. L. McIntyre, "A preliminary assessment of mercury in the feathers of migratory songbirds breeding in the North American subarctic," Ecotoxicology (2019); the NPS summary is a work of the United States government in the public domain, and the paper's abstract is paraphrased.