[ad_1]
A careful reenactment of a three-decade old study of birds on the side of a mountain in Peru has given scientists a unique opportunity to prove how the changing climate keeps species from where they are best adapted.
Surveys conducted on more than 400 bird species in 1985 then in 2017 revealed that almost all populations had declined, until eight of them had completely disappeared and almost all of them had died. were moved to higher altitudes, what scientists call "an extinction factor towards extinction". "
"Once you have reached the limit of your capacity, there will be no more," said John W. Fitzpatrick, one of the authors of the study and director of the Cornell Laboratory of Ornithology.
"On this particular mountain, some bird populations have been literally eliminated."
There is no certainty that birds have changed ranges due to changes in temperature or indirect impacts, such as changes in the range of insects or seeds they feed on.
A Black Chin Mountains Tangara, endemic to northeastern India, perched. Courtesy of image: IBC
The results of the study, Posted in the Proceedings of the National Academy of Sciences, confirms what biologists have suspected for a long time, but have had little opportunity to confirm.
The existence of a 1985 survey of birds of the same mountain provided scientists with a rare and useful baseline.
Previous research has documented habitats of birds and other species moving in altitude or latitude in response to warming temperatures. But Mark Urban, director of the Center of Biological Risk at the University of Connecticut, who did not participate in the study, said.
"A study like the one where you have historical data that you can go back to and compare to is very rare," Urban said. "As long as the species can disperse, you will see them ascending the mountain, until this escalator becomes a staircase that leads to paradise."
In 1985, Fitzpatrick established a base camp along a river descending a mountain slope in southeastern Peru, with the goal of listing habitat areas of bird species tropical people who lived there. His team spent several weeks traveling the Cerro de Pantiacolla, using thin nets called Japanese nets to catch and release birds, and holding detailed logs of birds captured, spotted or heard chirping in the forests.
Two years ago, Fitzpatrick sent his journals, photos and other material to Benjamin Freeman, a postdoctoral fellow at the Biodiversity Research Center at the University of British Columbia. Freeman, who has been researching tropical birds for more than a decade, undertook to recreate the trip in August and September 2017. With the help of old photos offering a mountain view, his team has located the same base camp.
The Malabar Trogon, a winter resident of the Western Ghats and an endemic bird of India. Image courtesy: Birds of Gujarat
Freeman has largely reconstructed Fitzpatrick's trajectory and methodology to see what had happened in the middle years, a period when average average temperatures on the mountain increased by 0.76 degrees Fahrenheit (0.42 degrees Celsius) . Because the mountain is at the edge of a national park, the area has not been disturbed.
In addition to deploying driftnets on the slopes, the Freeman team placed 20 microphones on the mountain to record bird sounds that were hard to see.
"We found that bird communities were climbing the slope to reach the climatic conditions to which they were initially adapted," said Freeman, the lead author of the study.
Near the top of the mountain, bird species averaged 98 meters (321 feet) in height.
"We think temperature is the main lever for why species live where they live on the slopes of the mountains," Freeman said. "A large majority of species in our study were doing the same thing."
Birds adapted to live in narrow temperature bands – in regions with little seasonal variation – could be particularly vulnerable to climate change, Fitzpatrick said. "We should expect what happens on this mountain peak to occur more generally in the Andes and other tropical mountain ranges," he said.
[ad_2]
Source link
