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September 2007

Species We Can Kiss Goodbye

These dozen creatures are threatened by global warming.

Conditions in America’s mountains will push these animals into extinction–or Canada.

What’s killing pikas in the Rocky Mountains? It’s the heat. Scientists predict that these adorable “rock rabbits” will die off within the next few decades as rising temperatures overwhelm their ability to adapt or migrate. In general, alpine animals are faring poorly in a warming world, mainly due to their elevated, isolated habitats. Species that depend on fir forests, frigid winters, and heavy snowpack are hitting a topographical wall that blocks their attempts to escape the heat. As a result, scientists expect climate change to spawn a new wave of endangered and locally extinct plants and animals, starting with the species described below.

American pika
The high-pitched chirp of this tiny mammal could soon fade to silence within alpine zones in the Rockies and Sierra. Intolerant of heat and dependent on talus slopes for food and protection, the pika is running out of high-elevation terrain to escape rising temperatures. As a result, it could be one of global warming’s first documented extinctions. In the last 40 years, nearly a third of the pika population in the Great Basin (the drainage between the Rockies and Sierra) has vanished. Donald Grayson, a University of Washington evolutionary ecologist who authored another key study, describes this animal’s future as “markedly insecure.”

This tenacious scavenger, known to challenge a grizzly bear over a carcass, has staved off two centuries of persistent trapping and habitat destruction. But the effects of global warming might finally chase it out of its northern Rockies sanctuary. Slow to reproduce and requiring an enormous range, wolverines depend on deep snowpack for both shelter (a den for giving birth in early spring) and food (animals killed by cold and avalanches). But its preferred habitat will shrink as winters get milder and snowline rises; climate models predict a snowline increase of 150 feet per decade, which will force the wolverine steadily northward.

According to a long-term study at the Rocky Mountain Biological Laboratory, the internal clock of the yellow-bellied marmot is wildly askew. The animal is coming out of hibernation 38 days earlier in the spring than its forebears did 23 years ago, and the study’s author, biologist David Inouye, blames climate change. The consequences of this premature wakeup? The marmot awakens to more snow cover (22 inches deeper on average), and the lack of food can force it back to bed. When it rises the second time, it burns muscle instead of fat to jump-start its metabolism–which makes it vulnerable to starvation and predation.

Bicknell’s thrush
Every spring, this sparrow-sized brown songbird migrates from the Caribbean to the northern Appalachians, where the entire population breeds in conifer forests above 4,000 feet. Notoriously shy and picky, the Bicknell’s thrush nests almost exclusively in balsam firs. As global warming threatens its tree of choice, this rare bird has become of the most range-restricted breeding species in eastern North America. A 2002 study predicted that a temperature increase of 1.5 to 6.3°F by 2100 could thin balsam trees in New England by 96 percent as advancing hardwoods such as beeches and yellow birches crowd them out.

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