The North American tree swallow is among the bird species beginning springtime activities earlier than historically recorded. Field biologists, who kept track of some 21,000 tree swallow nests in the United States and Canada over the last 40 years, concluded that the average egg laying date for female swallows has advanced by nine days - a phenomenon that mirrors other North American studies confirming higher temperatures and the earlier arrival of spring.
Long term observations of flowering plants in Wisconsin show that wild geraniums, columbine and other species are blooming earlier than before.
Studies in Colorado found that marmots are ending their hibernations about three weeks sooner than they were in the late 1970s.
Measurements taken in Alaska revealed that growth in white spruce trees has been stunted in recent years - another expected consequence of a rapidly warming climate, Root said.
"Climate change models predict that the poles will warm more quickly than the equator, so it's not surprising that we're getting the strongest signals of biological change from Alaska and other northern regions," Root said.
environmental news service January 2, 2003
