Hundreds of tropical bird species at risk of extinction

China National News (ANI) Tuesday 6th March, 2012

Researchers have cautioned that up to 900 species of tropical land birds around the world could become extinct by 2100.

The finding is modelled on the effects of a 3.5C Earth surface temperature rise.

Species may struggle to adapt to habitat loss and extreme weather events, said author Cagan Sekercioglu, assistant professor of biology at the University of Utah.

Some tropical mountain birds such as Venezuela's scissor-tailed hummingbird and East Africa's regal sunbird are endemic to their habitats and have limited capacity to move, which could make these species especially vulnerable.

Loss of land due to rising sea levels is one of the threats faced by tropical island species. The mangrove finch on the Galapagos Islands, the Abbott's booby on Christmas Island and Mexico's Cozumel thrasher are at risk.

Hundreds of restricted-range species could be under threat, including the horned guan, the Cochabamba mountain-finch, the red-fronted parrotlet and the blue-eyed ground-dove.

Depending on future habitat loss, each degree of surface warming could affect between 100-500 species, stated Sekercioglu.

Sekercioglu noted that tropical mountain species are among the most vulnerable. He explains that bird species will need to be able to adapt physiologically to changes in temperature and be able to move to higher altitudes if they are to survive, the BBC reported.

He says cooler, more humid forests could recede higher up mountains and combined with human settlements at higher altitudes, forest habitat could "get pushed off the mountain".

This would create "an escalator to extinction" he warned.

"Coastal species are also vulnerable - as coastal forest can be sensitive to salinity, and these forests can get hit harder by hurricanes and typhoons, and these events are also expected to increase," he added.

Birds in extensive lowland forests with few mountains in places such as the Amazon and Congo basins - may have trouble relocating, while tropical birds in open habitats such as savanna, grasslands, scrub and desert face shrinking habitats.

Tropical birds in arid zones are assumed to be resilient to hot, dry conditions, but they could suffer if water sources dry out.

Mike Crosby, senior conservation officer in Asia at Birdlife International also said: "We know that quite a lot of tropical birds are not very good at dispersing so this could be a big issue in the future if the suitable climate moves several hundred kilometres or even tens of kilometres, some of the birds might not be able to move their ranges sufficiently quickly in response to that.

"We might have to take novel conservation measures in the future such as translocation of birds from one site to another."

The study looked at how manakins, of which there are 45 species in the neotropical region, would cope. Results showed that manakins limited to the lowland habitats of the Amazon and Cerrado in Brazil, would be most affected as they could lose up to 80 percent of their habitat; as many as 20 percent of the Cerrado manakin species are expected to go extinct.

The study appeared in Biological Conservation Journal paper. (ANI)