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|Regional Issue: Mercury||
The Saltmarsh Sparrow: An alarm for mercury contamination?
The Problem and Effects:
Wildlife exposed to certain levels of mercury can experience reproductive failure, impaired muscular coordination, behavior abnormalities, abnormal vocalization, vertigo, convulsions, paralysis and death.
What We're Doing:
Birds were captured from June to August using mist nets, and blood was collected for mercury analysis. Results showed that mercury levels in the blood of adult sparrows were significantly higher in birds captured from Parker River National Wildlife Refuge than from other refuges sampled, and the mercury contamination may be impacting the overall health of this songbird species. Our continuing research attempts to identify potential point sources of mercury that might explain the elevated levels at Parker River.
Mercury accumulates at potentially harmful rates in populations on breeding sites, so researchers wondered whether the same problem occurs in areas where the sparrows go during winter. The Service partnered with the Center for Conservation Biology at the College of William and Mary to assess mercury levels in sparrows on wintering areas at several National Wildlife Refuges in Virginia.
The results to date suggest that saltmarsh sparrows, which nest along the northeastern coast of North America, lower their mercury levels when they migrate to wintering grounds along the southeastern coast. This may be due to a shift in diet downwards on the food chain, for example, fewer insects and more seeds.
But it may also reflect lower environmental mercury levels.
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July 20, 2015