Bird Extinctions Likely to Rise with Climate Change
As warming temperatures push organisms to seek cooler climates at ever-higher altitudes, habitat areas are shrinking, putting many species of plants and animals at risk. This trend could have particularly dire consequences for the world’s bird populations, according to a new report in the journal Conservation Biology. “It’s like an escalator to extinction,” says lead author Cagan Sekercioglu, a senior research scientist with the Department of Biological Sciences at Stanford University. “As a species is forced upwards and its elevational range narrows, the species moves closer to extinction.”
“Vegetational shift is the key issue here,” Sekercioglu says, noting that, “Birds will follow the shift in habitat.” As plants move upslope, the surface area of a bird’s habitat may diminish—and if the top of the mountain is still too warm, the species can die out. Problems also arise if there is too little moisture at higher altitudes to support vegetation or if changes in soil composition are incompatible with the vegetation creeping upward. Diseases from lower elevations may be more likely to infect highland bird species, and species already present at higher altitudes may clash with encroaching birds, the study notes.
The research team modeled changes to the elevational ranges of some 8,400 species of land birds (the vast majority of all bird species) using 60 scenarios that incorporate habitat loss estimates from the 2005 Millennium Ecosystem Assessment as well as the latest climate projections from the Intergovernmental Panel on Climate Change. With a “worst-case scenario” warming of 6.4 degree Celsius, up to 30 percent of land-bird species could go extinct by 2100. With an “intermediate” level of warming of 2.8 degrees Celsius, 400 to 550 land-bird extinctions are expected. “Of the land-bird species predicted to go extinct, 79 percent of them are not currently considered threatened with extinction, but many will be if we cannot stop climate change,” Sekercioglu warns.
Because of the remoteness of many mountain ranges and a lack of funding for ornithological studies in most tropical countries, there is little data on avian responses to climate change. While amateur bird-tracking databases like the new site Geobirds are growing on the Internet, remote sensing data are becoming less available as image distribution moves to the private sector. “To effectively monitor their rate of change as warming progresses, especially in the species-rich topics, we need a lot more data on birds’ distributions and on the speed and extent of birds’ elevational shifts in response to climate change,” says Sekercioglu.
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