September 8, 2004
Director of Media Relations

AMHERST, Mass.- Ethan Clotfelter, an assistant professor of biology and neuroscience at Amherst College, recently completed a review that indicates that the increasingly bizarre behavior of animals all over the world-manic goldfish, confused frogs, fearless mice and seagulls that can't stand upright-may have an environmental cause: chemicals that interfere with the production and transportation of hormones.

Published in London in August in Animal Behaviour (vol. 68, p. 465), Clotfelter's review was also featured in New Scientist (Sept. 3, 2004.) He told the news magazine that researchers looking for environmental damage might look first at what animals are doing, as behavior is more easily perturbed than anatomical measures. "Toxicologists may be missing a trick: changes in animal behavior could be an early warning that certain chemicals are harmful. You might see behavioral effects long before you see a population crash."

The pollutants, known as endocrine disruptors, range from heavy metals such as lead to polychlorinated biphenyls (PCBs) and additives such as bisphenol A. According to New Scientist, "For decades, biologists have known that these chemicals can alter the behavior of wild animals. And in recent years it has become clear that pollutants can cause gender-bending effects by altering animals' physiology, particularly their sexual organs. But now two major reviews have revealed that the chemicals are having a much greater impact on animal behavior than anyone suspected. Low concentrations of these pollutants are changing both the social and mating behaviors of a raft of species. This potentially poses a far greater threat to survival than, for example, falling sperm counts caused by higher chemical concentrations."

Clotfelter looked at data on animals as diverse as egrets and gulls, snails, quails, rats and macaques, minnows, mosquito fish, falcons and frogs, and considered altered behaviors that include mating and parenting, nest building, learning, predator avoidance, foraging, activity levels and even balance. The New Scientist article is available online at

A member of the Amherst faculty since 2003, Clotfelter received a bachelor's degree in biology from the University of North Carolina at Chapel Hill, and M.S. and Ph.D. degrees in zoology from the University of Wisconsin at Madison.