Birds can only fly so far
The sky is the color of a robin's egg on the Barker Dam Loop Trail in Joshua Tree National Park, 215 miles southwest of Las Vegas. I'm hiking a section of trail that winds its way through an immense Joshua tree forest when an American kestrel wings over like a fighter plane, chasing a raven. She perches on a lone Joshua tree for a moment, her rust feathers glinting in the sunlight. Seconds later, she spreads her wings and jets up the canyon, disappearing over a pile of large, granite boulders. Moments like this have enchanted people long before John James Audubon began painting American birds in the 19th century. But will our desert birds survive the effects of 21st century climate change?
Scientist Lori Hargrove has been trying to answer that question. She knows that even desert birds have difficulty adapting to the hot, dry conditions of our California deserts. Hargrove remembers taking shelter from the heat during one of her bird surveys in a cave that was probably used by Native Americans hundreds of years ago. It was an especially hot day, and a flock of black-throated sparrows joined her in the cave, seeking shade. The respite wasn't enough: During the course of the afternoon, one sparrow died.
Hargrove's research shows that iconic desert birds like the cactus wren and the American kestrel are already on the move, shifting their ranges upward in elevation in response to climate change. Her research over a 26-year period comes from data collected at the Deep Canyon Research Station, just northwest of Palm Springs, Calif. "It will be particularly difficult for species (to adapt) that are already threatened by habitat destruction," she says.
Hargrove's concerns are echoed in a new report on birds by Audubon California, which warns that climate change will cause the local extinction of some California bird species while decreasing the range of others. One scenario in the report estimates that the mean annual temperature in California will rise from 3.5 degrees to 5.6 degrees Fahrenheit by the end of the 21st century, with increasingly irregular cycles of precipitation. Habitats will change in a short period of time, making it difficult for birds to adapt. By the end of the century, some areas of the California deserts may lose 25–to 50 percent of their bird species.
Our national parks and other protected lands preserve a variety of different habitats but were never designed to buffer species and ecosystems against large-scale climate change. Some people might wonder why birds affected by climate change don't just fly away to more suitable habitat; after all, they have wings, don't they? In fact, birds may have been able shift their ranges during past climate fluctuations. But recent, intensive human development in the Western United States has altered and destroyed a great deal of the habitat that the birds still have left. And now there's not enough time for plants and animals to successfully adapt and shift their ranges: Climate change is simply happening too fast.
Supporting legislation such as the Waxman-Markey climate bill as it goes to the Senate, also known as the American Clean Energy and Security Act of 2009, is essential because it sets aside revenue for the National Park Service and other federal agencies to acquire land for wildlife migration corridors while also restoring habitat and controlling invasive species. But it's equally important for each of us to do our part: Reduce our personal energy consumption and safeguard the water in our national parks and wildlife refuges on which the birds depend.
Back at the Barker Dam loop, I spy a cactus wren that flits effortlessly through the dense limbs and spines of a teddy-bear cholla. If we make an investment in our national parks and other protected areas, we can preserve birds like this and the subtle beauty of these arid landscapes. Centuries from now, if people can still experience the solitude and majesty of the California desert, hear the chatter of a cactus wren or see the glint of rust-colored feathers on an American kestrel, we will have done our job.
Seth Shteir is a contributor to Writers on the Range, a service of High Country News (hcn.org). He is senior program coordinator for air and climate at the National Parks Conservation Association in Joshua Tree, California.