Bicknell’s thrush migration routes Both Bicknell’s Thrush and Black-throated Blue Warbler winter primarily in the Greater Antilles in the Caribbean, where climate change brings a different set of environmental concerns. “Change is happening in the tropics, and there it’s not just temperature; it’s also the influence of precipitation,” Marra says. “Major droughts are occurring in the Caribbean, and are predicted to continue over the next 30 to 50 years.” Marra’s studies on wintering American Redstarts in the Caribbean have shown that the amount of winter precipitation directly influences the birds’ physical condition when departing in the spring for North America. “<strong>The</strong> abundance of redstarts throughout their breeding range is influenced more by winter climate than it is by breeding climate,” Marra says. Climate change threatens birds in ways that few could have predicted. <strong>The</strong> Gray Jay, a bird of the boreal forests of North America, depends for winter survival on food cached in fall. Warmer autumn temperatures cause this stored food to rot, diminishing breeding success the following spring. <strong>The</strong> Common Loon, an iconic waterbird of the North, has evolved to leave the freshwater lakes where it nests before a winter molt that leaves it flightless; warmer temperatures cause loons to delay their migration, so that when freezing weather does come they are trapped, unable to fly or find food. Though it’s probably true that it will be decades before significant numbers of bird species become endangered or suffer wide-scale extirpation as a direct result © Courtesy of the Vermont Center for Ecostudies “Change the temperature and that changes everything. It doesn’t do it instantaneously. It’s going to do it in fits and starts: ice storms in the Northeast, fires in the Southeast, drought in many areas.” of global climate change, it seems increasingly likely that serious impacts reducing biodiversity will show up long before that point. Populations of vulnerable species will decline, in some cases substantially. Species composition of birds and other organisms will change, as will complex ecological interactions, with unknown environmental consequences. “We’re changing the basic way the climate works on the planet,” Rodenhouse says. “Change the temperature and that changes everything. It doesn’t do it instantaneously. It’s going to do it in fits and starts: ice storms in the Northeast, fires in the Southeast, drought in many areas. <strong>The</strong>re’s going to be a period of tremendous variability as all these changes occur. What’s going to come out at the other end is going to be so dramatically different that we can’t even speculate.” David Moulton is <strong>The</strong> <strong>Wilderness</strong> <strong>Society</strong>’s director of climate change policy and a life-long birder. “In the past,” he points out, “a lone canary could issue a clear warning of dangerous gases by dropping dead in a mine shaft. When will we heed the warning of entire species facing extinction due to greenhouse gases?” <strong>The</strong> phoebes wintering near my home are sending us a clear message, as are the Carolina Wrens nesting in New York and the waterfowl that no longer fly so far south in the fall. Our climate is changing with a speed that could strain or snap vital strands in the web of planetary life—the relationships that sustain all of Earth’s organisms, including ourselves. Mel White is a freelance writer in Little Rock, Arkansas, and specializes in travel and natural history. He has written for National Geographic, Audubon, Living Bird, and Outside, and his books include National Geographic Complete National Parks of the United States. © Hope Coulter 14 1-800-THE-WILD
<strong>The</strong> Final Frontier By Marilyn Berlin Snell © Kevin Smith/AlaskaStock.com www.wilderness.org 15
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