Wednesday, February 22, 2012

Climate Change and Tropical Birds

A major concern for conservationists is how well animal and plant species will adapt to climate change. A particular problem are animals with isolated populations or specialist habits. Many such creatures can be found in the tropics, and a recent study looked into how tropical birds might fare. The results are not good:

There may be less birds for birders to see in the world as the planet warms. Climate change, in combination with deforestation, could send between 100 and 2,500 tropical birds to extinction before the end of century, according to new research published in Biological Conservation. The wide range depends on the extent of climate and how much habitat is lost, but researchers say the most likely range of extinctions is between 600 and 900 species, meaning about 10-14 percent of tropical birds, excluding migratory species.

"Birds are perfect canaries in the coal mine—it's hard to avoid that metaphor—for showing the effects of global change on the world's ecosystems and the people who depend on those ecosystems," says lead author and notable ornithologist Çağan Şekercioğlu with the University of Utah. "Compared to temperate species that often experience a wide range of temperature on a yearly basis, tropical species, especially those limited to tropical forests with stable climates, are less likely to keep up with rapid climate change."

Şekercioğlu and colleagues scoured 200 scientific studies related to tropical birds and climate change to develop their estimate, which is in line with previous estimates of bird declines linked to a warming planet.

Those birds most susceptible to climate change impacts include high-elevation species which could quite literally run out of habitat, and those already restricted to small ranges. An increase in extreme weather events, such as droughts and storms, may also imperil some species. The increasing intensity of hurricanes, even if frequency diminishes, may threaten coastal birds, while long droughts could hurt birds' ability to find food during breeding season. Already, the Amazon has suffered two record droughts in the last 7 years, leading many scientists to fear for the ecosystem's resiliency in the face of climate change.

Disease may also pose a problem. Malaria is expected to spread to higher altitudes and latitudes, possibly imperiling some tropical bird species. Rising sea levels may also pose a problem for coastal and island birds.
It is important to remember that birds do not just depend on a patch of habitat at a certain temperature but on the complex of plants and invertebrate and vertebrate animals that live there. Many species may be able to shift their ranges, but others will run into significant trouble if their favored habitats are not able to move along with them.