Global Warming Affects Animals at High Altitudes
A long-term study in Colorado by Dr. David Inouye, supported by Earthwatch teams, shows that climate change may disrupt the normal cycles of mountain animals.
Earthwatch Institute, Maynard, MA, 11 May 2000-University of Maryland ecologist Dr. David Inouye (Rocky Mountain Wildflowers) has shown that climate change caused by global warming is disrupting the normal hibernation, migration, and reproductive cycles of animals that spend winters at lower altitudes and summers at higher altitudes (above 2,900 meters). Differences in the effects of global climate change at different altitudes, Inouye says, are to blame.
The 25-year-old study, co-funded by Earthwatch Institute and the National Science Foundation, was based at the renowned Rocky Mountain Biological Laboratory (RMBL) in Gothic, Colorado. For 16 summers, from 1982 through 1998, Inouye directed Earthwatch Institute teams monitoring plants, pollinators, birds, and other animals in the meadows and forests around RMBL. He and his volunteers helped document that global warming affects lower altitudes differently than higher ones. As a result, animals exposed to earlier warm weather at lower altitudes may exit hibernation and birds may flock north while there's several feet of snow on the ground, risking starvation.
For instance, over the past 23 years, marmots (close relatives of woodchucks), which usually hibernate for eight months during the long winter at high altitudes, are emerging from hibernation 38 days earlier. And over the past 19 years, American Robins that migrate from low altitude wintering grounds to high-altitude summer breeding grounds in Colorado have been arriving 14 days earlier, and must wait longer for snow to melt before they can feed and nest. The long-term study, reported in the February 15 issue of the Proceedings of the National Academy of Sciences, indicates that such animal and bird confusion has become commonplace over the last 25 years as a result of global warming.
The researchers' work suggests that other hibernating mammals at high altitudes, such as ground squirrels, chipmunks, and bears, may also risk starvation as a result of global warming. "There is growing evidence to support that climate change is resulting in earlier and longer growing seasons at low altitudes, earlier migrations by some bird species, and earlier reproduction in both plants and animals," said Inouye, lead investigator and director of Maryland's graduate program in Sustainable Development and Conservation Biology.
Over the past 25 years, Inouye found a striking contrast at altitudes greater than 2,900 meters in the Colorado Rocky Mountains, where spring has not been arriving any earlier, and the growing season has started later. "In the past, marmots' ability to detect warmer temperatures was advantageous because it signaled an early spring, which resulted in a longer growing season and a longer growing season enhances animal survival and production," said Kenneth Armitage, co-author and University of Kansas distinguished professor emeritus of systematics and ecology.
Armitage continued, "Now, it appears the marmots response to temperature may have a negative effect, reducing chances for survival and reproduction." According to Inouye, this kind of long-term study is so valuable, because it shows the slow rate of significant changes that are occurring over recent decades. "Almost anyone can make a relatively simple observation, such as the first sighting of a robin each spring," said Inouye, and, if continued for a long-enough time, can provide important insights into global change.
The research will continue with investigations of the low-to-high altitude migration of hummingbirds; other hibernating mammals, such as chipmunks and ground squirrels; and the effects of climate change on wildflowers.
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