by Richard Conniff/Yale Environment 360
A shift in home range by a handful of bird species along an obscure ridge in the Peruvian Andes might once have seemed like sleepy stuff, even to ecologists. Instead, it made headlines last month when researchers reported that the birds’ uphill push for cooler terrain has already resulted in population losses for most species and the probable extirpation of five species that were common at the top of the ridge just 33 years ago.
It was some of the strongest evidence yet for the long-standing prediction by scientists that climate change will lead — is leading now — to widespread loss of wildlife. University of British Columbia ecologist Ben Freeman and his co-authors summed up their findings with a chilling metaphor: Mountain birds, they wrote, are “riding an escalator to extinction.”
The study, in the Proceedings of the National Academy of Sciences, didn’t report any actual extinctions. The Cerro de
Pantiacolla rises to a maximum height of only 4,642 feet, and the birds that disappeared from the ridgetop persist on higher and larger mountains — in effect, on other escalators — elsewhere in the area. Reliable scientific evidence that climate change has caused actual extinctions is in fact scarce so far, despite projections by climate modelers that such extinctions are likely. The only known example is a marsupial called the Bramble Cay melomys, which vanished sometime after 2009 from a low-lying island off northern Australia, after sea level rise and extreme weather caused repeated inundation of its habitat.
But the new study from Peru lends support to the predictions being made by climate modelers. It also fits into a rapidly expanding body of evidence that plants and animals everywhere are on the move as they struggle to adjust to climate change. The ecological upheaval is “happening right now and it will almost certainly continue to happen,” says Freeman, lead author of the Peru study, and “there is an immediacy to something happening right before our eyes that’s different from a study saying, ‘this is what it’s going to be like in 2100.’”
When plants and animals move uphill, they can lose habitat, simply because mountains become smaller the higher you climb. A shift in range can also mean the loss of old partnerships, the introduction of Read the rest of this entry »