Chirp-filled summer mornings may sound a bit different in the future. By the end of the century, climate change will have forced more than half of North America's bird species to change feeding and breeding grounds, according to a new study. For American bird-lovers, that means seeing new species at the bird feeder, and watching some old friends fly away for good.
The changes can have grave consequences for birds. Out of 588 bird species whose fates the new study's scientists modeled, more than one in five are expected to see the size of their habitats shrink by more than half by 2050, the team reports today in the journal PLoS One. And the bird species that are most threatened by climate change aren't always the ones we think of as being endangered now, write the researchers, a team from the National Audubon Society. One example is Baird's sparrow, a brown, spotted sparrow that's common in the Midwest grasslands. The International Union for Conservation of Nature considers Baird's sparrows to be a "species of least concern," but by 2050, they will have lost more than 95 percent of their habitat, the study finds. The Audubon folks recommend conservation groups start monitoring these "climate-endangered" species, even though they seem to be doing fine now.
More than one in five birds are expected to see the size of their habitats shrink by more than half by 2050.
Birds aren't the only creatures expected to significantly change their ranges—the regions where they live and breed—in the future. Indeed, in previous studies, researchers found plants, marine animals, and Arctic species have already shifted their ranges because of climate change. Birds offer just another example of the upheaval that the natural world is undergoing, and will most likely continue to endure.
Climate change forces plants and animals to move in various ways. In search of cooler temperatures, species may migrate north or further up mountains. Changes in animals' ranges can be disruptive not only because they may lose ground, as 21 percent of American birds will, but because they'll have to deal with new neighbors (not all species in a habitat will move together in response to global warming). That can lead to some difficult-to-deal-with consequences. For example, what if a bird species ends up moving north, but the plants it likes to eat move up in elevation instead?
The silver lining is that birds, at least, are already beloved and well watched. The study depends on data from the North American Breeding Bird Survey and the Audubon Christmas Bird Count, in which birding enthusiasts follow specific protocols to record all the bird species they spot in their area in the summer and winter. The surveys are among the largest, longest-running citizen science projects on the planet. There are already many eyes on our feathered friends. Now they have a list indicating which ones deserve extra attention while the world warms.
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