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Mercury Research
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My current focus is on mercury contamination in the headwaters of the Shenandoah River in central Virginia. This project arose after a conversation with a toxicologist from the US Fish & Wildlife Service who wondered aloud whether mercury that leaked into the South River from 1929-1950 was harming birds. While everyone knows that mercury is bad for animals, the consensus ends there. During four field seasons my lab made major discoveries about the movement of mercury through the food chain and the effects (and lack thereof) of various levels of mercury on reproduction and survival in numerous bird species. Most significantly, we discovered that mercury from a river has entered the surrounding terrestrial food chain and accumulates in terrestrial spiders that are eaten by songbirds. This leads to higher levels of mercury in forest songbirds than in fish-eating birds, which have long been considered the only group at risk. Now we are carrying out research in the more controlled environment of the laboratory to determine how, when, and why mercury affects songbirds.  Current students work on the effects of chronic, low level mercury exposure on songbird development, endocrine and immune function, song, reproductive success, behavioral ecology (foraging, fighting, mating, escaping, etc.) and more.


Related Links

Mercury: A hazard without borders

iibbs Mercury Projects

Mercury on the Move Video

South River Science Team


Recent Mercury Publications


Undergraduate author

Masters student author

Alumni author



  • Bouland, A.J., White, A.E., Lonabaugh, K.P., Varian-Ramos, C.W., & Cristol, D.A. In press. Female-biased offspring sex reatios in birds at a mercury-contaminated river. Journal of  Avian Biology. (pdf)
  • Cristol, D.A., Mojica, E.K., Varian-Ramos, C.W. & Watts, B.D. 2012. Feather mercury indicates low mercury in Bald Eagles of Chesapeake Bay, Virginia. Ecological Indicators 18: 20-24. (pdf)


  • Northam, W.T., Allison, L.A. & Cristol, D.A. 2011. Using group-specific PCR to detect predation of mayflies (Ephemeroptera) by wolf spiders (Lycosidae) at a mercury-contaminated site. Science of the Total Environment (pdf)
  • Cristol, D.A., Smith, F.M., Varian-Ramos, C.W., & Watts, B.D. 2011. Mercury levels of Nelson's and Saltmarsh Sparrows at wintering grounds in Virginia, USA. Ecotoxicology 20: 1773-1779. (pdf)
  • Jackson, A.K., D.C. Evers, M.A. Etterson, A.M. Condon, S.B. Folsom, J. Detweiler, J. Schmerfeld, & D.A. Cristol. 2011. Mercury exposure affects the reproductive success of a free-living terrestrial songbird, the Carolina Wren (Thryothorus ludovicianus). Auk 128: 759-769.(pdf)
  • Jackson, A.K., D.C. Evers, S.B. Folsom, A.M. Condon, J. Diener, L.F. Goodrick, A.J. McGann, J. Schmerfeld, & D.A. Cristol. 2011. Mercury exposure in terrestrial birds far downstream of an historical point source. Environmental Pollution 159:3302-3308.(pdf)
  • Hallinger, K.K., Cornell, K.L., Brasso, R.L. & Cristol, D.A. 2011. Mercury exposure and survival in free-living swallows (Tachycineta bicolor). Ecotoxicology 20: 39-46. (pdf)
  • Varian-Ramos, C.W., Condon, A.M., Hallinger, K.K., Carlson-Drexler, K.A. & Cristol, D.A. 2011. Stability of mercury concentrations in frozen avian blood samples. Bulletin of Environmental Contamination and Toxicology 86: 159-162. (pdf)
  • Hallinger, K.K. & Cristol, D.A. 2011. The role of weather in mediating the effect of mercury exposure on reproductive success of tree swallows (Tachycineta bicolor). Ecotoxicology 20: 1368-1377. (pdf)


  • Edmonds, S. T., D. C. Evers, D. A. Cristol, C. Mettke-Hofmann, L. L. Powell, A. J. McGann, J. W. Armiger, O. P. Lane, D. F. Tessler, P. Newell, K. Heyden, and N. J. O'Driscoll. 2010. Geographic and seasonal variation in mercury exposure of the declining Rusty Blackbird. Condor 112:789-799. (pdf)
  • Brasso, R.L., Abdel Latif, M.K. & Cristol, D.A. 2010. Relationship between laying sequence and mercury. Environmental Toxicology and Chemistry 29: 1155-1159 (pdf)
  • Hallinger, K. K. & Cristol, D. A. 2010. Use of a chemical tracer to detect floaters in a tree swallow (Tachycineta bicolor) population. J. Environmental Indicators 5: 7-16 (pdf)
  • Sleeman, J. M., Cristol, D. A., White, A. E., Evers, D. C., Gerhold, R. W. & Keel, M. K. 2010. Mercury toxicity in a North American River Otter (Lontra canadensis). J. Wildl. Disease 46: 1035-1039. (pdf)
  • Hallinger, K.K., Zabransky, D.J., Kazmer, K.A. & Cristol, D.A. 2010. Birdsong Differs Between Mercury-Polluted and Reference Sites. Auk 127:156-161. (pdf)


  • Wada, H., Cristol, D.A., McNabb, F.M.A. & Hopkins, W.A. 2009. Suppressed adrenocortical responses and thyroid hormone levels in birds near a mercury-contaminated river. Environmental Science & Technology 43: 6031-6038. (pdf)

  • Hawley, D.M., Hallinger, K.K. & Cristol, D.A. 2009. Compromised immune competence in free-living tree swallows exposed to mercury. Ecotoxicology 18: 499-503. (pdf)
  • Condon, A.M. & Cristol, D.A. 2009. Feather growth influences blood mercury level of young songbirds. Environmental Toxicology and Chemistry. 28(2):395-401. (pdf)


  • Cristol, D. A., Brasso, R. L., Condon, A. M.Fovargue, R. E.Friedman, S. L.Hallinger, K. K., Monroe, A. P. & White, A. E. 2008. The movement of aquatic mercury through terrestrial food webs. Science 320:335. (pdf)

  • Brasso, R.L. & Cristol, D. A. 2008. Effects of mercury exposure on reproductive success of tree swallows (Tachycineta bicolor).  Ecotoxicology  17: 133-141. (pdf)