Warming and Wildlife Behavior

Scientists have been studying the behavior of wildlife for any signs that animals are being affected by changes in Earth's climate, which appears to be warming slowly. Some researchers, for example, have reported that butterflies seem to be moving northward in Europe.

Now, separate teams of researchers have identified similar changes in the breeding behavior of birds in England and the United States.

Chris D. Thomas and Jack J. Lennon of the University of Leeds in England analyzed the breeding distribution of British birds over a 20-year period and found that many species have moved north by an average of about 12 miles.

"This general northward shift took place during a period of climatic warming, which we propose might be causally involved," the researchers write in the May 20 issue of Nature.

Meanwhile, Jerram L. Brown of the State University of New York at Albany and colleagues, comparing 1971 and 1998, found that Mexican jays in southeastern Arizona were nesting and laying eggs about 10 days earlier.

"These changes were associated with significant trends toward increased monthly minimum temperatures on the study area, traits that are associated with the onset of breeding in this population," the researchers write in the May 11 Proceedings of the National Academy of Sciences.

Compiled from reports by Rob Stein.