Ecotoxicology

, Volume 20, Issue 8, pp 1773–1779 | Cite as

Mercury levels of Nelson’s and saltmarsh sparrows at wintering grounds in Virginia, USA

  • Daniel A. Cristol
  • Fletcher M. Smith
  • Claire W. Varian-Ramos
  • Bryan D. Watts
Article

Abstract

Nelson’s and saltmarsh sparrows (Ammodramus nelsoni and A. caudacutus) have recently been recognized as separate species, and because of their limited distributions and the susceptibility of their wetland habitats to climate change, these two new species are of conservation concern. Both species are known to bioaccumulate mercury at breeding sites in New England, USA where their ranges overlap, with the saltmarsh sparrow reported to have twice the concentration of blood total mercury. In this study we sampled both species on their shared wintering grounds, and documented that mercury exposure is lower than that reported for the breeding range, with saltmarsh sparrow blood mercury 2.6 times higher than in Nelson’s sparrow. Feather mercury, which is incorporated on the breeding grounds, confirmed that saltmarsh sparrows had incorporated 2.3 times more mercury than Nelson’s sparrows during the previous breeding season. A comparison of stable isotopes of nitrogen and carbon suggests that the higher exposure of saltmarsh sparrows may be not due to feeding at a higher trophic level, as previously hypothesized, but rather could be related to a difference in the carbon source at the base of each species’ food chain. This study, along with recently published data from both species on additional breeding and wintering grounds, provides a more complete picture of relative mercury exposure. Saltmarsh sparrows are exposed to mercury levels that warrant concern, with the highest exposure being during the breeding season. Areas set aside for the long-term conservation of this species should be carefully assessed for mercury bioaccumulation.

Keywords

Chesapeake Bay Mercury Nelson’s sparrow Saltmarsh sparrow Stable isotopes Wintering ground 

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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Daniel A. Cristol
    • 1
  • Fletcher M. Smith
    • 2
  • Claire W. Varian-Ramos
    • 1
  • Bryan D. Watts
    • 2
  1. 1.Department of Biology, College of William & MaryInstitute for Integrative Bird Behavior StudiesWilliamsburgUSA
  2. 2.Center for Conservation Biology, College of William & MaryWilliamsburgUSA

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