Climate change could be to blame for the collapse of bird populations in the desert along the Nevada-California border in the United States, scientists say.
The number of bird species has fallen by an average of 43 per cent over the past century at survey sites across an area larger than New York state, according to a new study by researchers at the University of California, Berkeley.
The study shows almost a third of species are less common and widespread now than they once were throughout the region.
The study's authors, Steven Beissinger and Kelly Iknayan, point to less hospitable conditions in the Mojave Desert as the probable cause.
"California deserts have already experienced quite a bit of drying and warming because of climate change, and this might be enough to push birds over the edge," said Iknayan, who conducted the research for her doctoral thesis.
"It seems like we are losing part of the desert ecosystem."
"The Mojave Desert is now nearly half empty of birds," said Beissinger, a professor of environmental science, policy and management.
"This appears to be a new baseline, and we don't know if it's stable or if it will continue to decline."
The researchers spent three years searching for birds at 61 locations on both sides of the border, including survey sites in the Spring Mountains and at Desert National Wildlife Refuge, just outside of Las Vegas, the Las Vegas Review-Journal reported.
They also surveyed sites across Death Valley and Joshua Tree national parks and Mojave National Preserve.
Iknayan revisited the same sites UC Berkeley biologist Joseph Grinnell and his colleagues surveyed between 1908 and 1947.
Iknayan and Beissinger found that areas with reduced rainfall lost more birds species than sites that remained wetter.
Their findings were published earlier this month in the journal Proceedings of the National Academy of Sciences.
