The number of wading birds in the U.K. has fallen steeply over the last decade, due in part to climate change forcing the birds out of their usual habitat, according to a new report.
The U.K.’s Wetland Bird Survey, released this month, found that some populations of waterbirds dropped to their lowest levels in 30 or 40 years in 2012 and 2013, and that though many factors are likely contributing to these declines, climate change is likely one of them.
“I think we should be quite alarmed because the declines for many of these species are pretty consistent,” Chas Holt, Head of the Wetland Bird Survey, told the Guardian. “Species like the ringed plover, redshank and dunlin, their decline has been consistent for 10 to 20 years now. And there is no obvious change happening, so in 10 years time we could be well down on numbers.”
Climate change’s impact on birds around the world has been well-documented. One study, from researchers at Duke University, found that rising temperatures were forcing birds in Peru to shift their ranges uphill as lower altitudes warm. But the study also found that the birds weren’t shifting fast enough to keep up with a warming climate.
“[These birds] tend to have very small ranges, which makes them more vulnerable to threats, be that human threats or climate change or whatever, Study author German Forero-Medina told WUNC. “If warming continues, eventually they might run out of habitat.”
A report from the National Wildlife Federation last year outlined the multitude of risks that birds are facing from climate change, including mismatches in migration time, food, and resources at their migration destination. This mismatch can be caused by earlier-than-usual springs, or springtime weather that gets warm and then dips down into low temperatures again. Many species of migratory birds depend on triggers such as changes in day length to know when to migrate, but if spring starts earlier in their migration destination region, they may arrive to find that they’ve missed the bud burst or insect hatching that they need to sustain themselves.
The NWF report found that, like the tropical birds in Peru, many North American birds have also changed their ranges: “177 of 305 species of birds tracked in North America have shifted their centers of abundance during winter northward by 35 miles on average,” the report stated.
At the same time, some of the weather events that can be exacerbated by climate change are also harming birds. In California, wildlife officials warned on Wednesday that the state’s epic drought could seriously harm waterfowl, especially those that rely on the Central Valley as a resting and wintering spot during migration. The Central Valley, which is one of North America’s most important bird habitats, is made up of wetlands and flooded rice fields, which make an ideal spot for waterbirds to land during their migration. This year, with water supplies restricted and rice acreage reduced, the valley will provide far less habitat for migrating waterfowl, forcing them into crowded conditions that make deadly botulism outbreaks more likely. Already this year, as the Sacramento Bee reports, 1,700 waterfowl died at Tule Lake National Wildlife Refuge in California, with botulism suspected as the cause.
And, due to a better-than-usual breeding season this year in Canada, a record-high number of birds will be migrating south, exacerbating the problem of crowding.
“I think we’re looking at the probability of a food shortage in addition to a disease outbreak,” Mark Biddlecomb, Western region director of Ducks Unlimited, told the Sacramento Bee. “If they don’t go back in excellent condition, they’re not going to be breeding like they would normally, and that will affect the entire flyway from the boreal forests of Canada all the way down to Mexico, frankly.”