Global warming and the destruction of natural habitats will cause significant declines and extinctions in the world's 8,750 terrestrial bird species over the next century, according to a new study published in the June 5 issue of the journal PLoS Biology.
The study, carried out by biologists at the University of California, San Diego and Princeton University, is the first global assessment of how climate change and habitat destruction may interact to impact the distribution of a large group of vertebrates over the next century.
The scientists warn in their study that, even under the most optimistic scenarios of controlling climate change and protecting habitats, at least 400 bird species are projected to become imperiled by the year 2050 due to reductions in their geographic ranges of greater than 50 percent.
All estimates in the study are based on the assumption that birds will not dramatically shift their geographic ranges in response to a changing climate.
"We found in our study that under certain assumptions by the year 2100, 950 to 1,800 bird species may be imperiled or even driven to extinction by climate change and habitat destruction," says Walter Jetz, an assistant professor of biological sciences at University of California in San Diego and the lead author of the study. "Most of these species are currently not recognized as imperiled."
"It's clear that both climate change and habitat destruction pose grave threats to many of the world's birds and, by analogy, to other species as well," says David Wilcove, a professor of ecology, evolutionary biology and public affairs at Princeton University and a co-author of the study. "Neither problem can be addressed in a vacuum."
The researchers say a vastly expanded network of wildlife reserves in the tropics, coupled with more ambitious goals to reduce greenhouse gas emissions and monitor the biodiversity impacts of climate change, will be needed to minimize global extinctions.
"The tragic irony here is that the protection of tropical forests is also one of the strongest buffers against future climate change," says Andrew Dobson, the third author of the paper and a professor of ecology and evolutionary biology at Princeton. "It is crucial that international environmental policy be swiftly developed to focus both on climate change and on habitat loss; the two are not only intimately related, but are arguably the greatest threats not only to birds, but also to human welfare and economic well-being."
"These hundreds of bird species headed toward extinction are like thousands of dying canaries in coal mines," Dobson adds.
"It's time we paid attention to them."