MELINA WALLING
Thu, October 19, 2023
FILE - A house sparrow is seen with an insect in its beak, May 25, 2020, in Lutherville-Timonium, Md. As climate change intensifies extreme heat, farms are becoming less hospitable to many nesting birds, including the house sparrow, a new study found on Thursday, Oct. 19, 2023. (AP Photo/Julio Cortez, File) (ASSOCIATED PRESS)
As climate change intensifies extreme heat, farms are becoming less hospitable to nesting birds, a new study found. That could be another barrier to maintaining rapidly eroding biodiversity that also provides benefits to humans, including farmers who get free pest control when birds eat agricultural pests.
Researchers who examined data on over 150,000 nesting attempts found that birds in agricultural lands were 46% less likely to successfully raise at least one chick when it got really hot than birds in other areas.
“I don’t think we expected it to be as extreme as it was,” said Katherine Lauck, a PhD candidate at University of California, Davis and lead author of the study published Thursday in the journal Science.
Bird scientists have been tracking the decline of avian wildlife for years. In 2019, a comprehensive study showed that there were three billion fewer wild birds than in 1970. The new study represents a closer look at what might be behind the dramatic decline.
Intense commercial farming is known to harm birds — fields completely clear of trees and other natural barriers lack shelter for wildlife, and pesticides and other agricultural chemicals can hurt birds.
The study concluded that species of higher conservation concern in the U.S. — those closer to being listed as federally threatened or endangered — were more vulnerable to extreme heat events in agricultural settings. But across the board, birds in forests were 14% more likely to achieve reproductive success in times of extreme heat.
The study's findings were not surprising to Ken Rosenberg, a biologist with the Road to Recovery initiative who formerly worked as a conservation biologist at the Cornell Lab of Ornithology and was lead author on what he calls the “three billion birds study.” The idea that forest birds could benefit slightly from warmer temperatures makes sense, he said, since shade from trees provides a buffer from extreme heat that agricultural areas don't have.
Rosenberg, who was not affiliated with this study, said he was pleased to see a paper in a prestigious journal using large datasets built from citizen science data. In this case, the observations came from NestWatch, a nationwide nest-monitoring program that anyone can participate in.
However, Rosenberg cautioned that more data might be needed to confirm that species of higher conservation concern were more vulnerable, since the overwhelming majority of the data involved species of low conservation concern.
The researchers predicted how different bird species might fare in each landscape during extreme heat events. They concluded that in agricultural areas, species of greater conservation concern, like the oak titmouse, would see worse outcomes than species of lower concern, like the house sparrow.
Rosenberg and David Bird, a professor emeritus of wildlife biology at McGill University, said the study contributes to the understanding of the negative effects of intensive single crop farming. Bird said the study “sings the praises of the need for preserving our forests,” which not only protect birds from hot weather but also help protect ecosystems from global warming by absorbing carbon.
The study suggests that if farmers purposefully left just a little more natural space around farms with a few trees or native plants — not necessarily changing everything about their operations — birds could better coexist with humans, Rosenberg said.
“Some of these open country birds don’t really need a lot of habitat or a lot of space," he said. "They just need some.”
Lead author Lauck is now working to better understand exactly why birds experience such large differences in nesting success between farmed and forested areas, hoping that would point toward useful interventions.
“New solutions that are neutral for farmers but helpful for biodiversity in the long term will create a more resilient biosphere for all of us,” they said.
___
Read more of AP’s climate coverage at http://www.apnews.com/climate-and-environment
___
Follow Melina Walling on X, formerly known as Twitter: @MelinaWalling.
___
Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.
As temperatures rise, songbirds struggle to keep young healthy, researchers find
Nidhi Sharma
Thu, October 19, 2023
Richard Heathcote
Songbirds like cardinals and sparrows follow the same schedule every year. In spring, they build nests and raise their young from nestlings to fledglings — but as springtime temperatures get warmer due to climate change, scientists have observed bird populations struggling to keep their offspring alive.
A study published Thursday in the journal Science examined over 150,000 nesting attempts from 1998 to 2020 and found that warmer-than-average temperatures during nesting seasons significantly hampered the reproductive success of over 50 bird species, particularly songbirds.
For birds nesting in agricultural spaces with little tree cover or shade, the probability of successfully raising at least one nestling dropped by 46% when temperatures were abnormally high.
The paper echoes rising concerns from ecologists and bird scientists, known as ornithologists, that the world is in the midst of a massive bird decline. Since the 1970s, North America’s bird population has dropped by almost 3 billion, and birds like sparrows, swallows, warblers and finches are continuing to disappear.
The alarming trend is likely due to several factors, such as pesticide pollution, habitat loss and climate change — including extreme heat that prevents nestlings from reaching maturity, said Katherine Lauck, a researcher at the University of California, Davis and lead author of the study.
In the nest, young birds are unable to regulate their body temperatures, which makes them more vulnerable to extreme temperatures, Lauck said. The nestlings are also completely dependent on their parents to bring them food, a task made more difficult in the heat, they added.
“The reproductive cycle of birds makes them particularly vulnerable to the impacts of climate change,” Lauck said.
Scientists have already found that rising temperatures have caused some species to nest earlier during cooler months and that some birds reaching maturity have been getting smaller. And in some cases, such as during Australia’s recent extreme heat waves, both baby birds and adult birds have dropped dead due to the heat.
The study emphasizes that the most vulnerable birds lived in unshaded agricultural areas, while those bird populations living in forests with plenty of tree cover and shade were largely unaffected by warmer-than-average temperatures — in fact, high temperatures slightly increased the probability of nestling success for forest birds.
The difference in reproductive success between forest and agricultural bird populations highlights how land use can exacerbate high temperatures for wild birds, said Conor Taff, an ecologist and researcher for the Cornell Lab of Ornithology who was not involved in the study.
Taff added that protecting bird populations from heat can be as simple as introducing forest patches in agricultural areas to give birds refuge from high temperatures, but the main work is reducing greenhouse gas emissions to limit global warming.
For many ecologists, conserving bird populations is essential for preserving healthy ecosystems. David Wiedenfeld, the senior conservation scientist at the American Bird Conservancy, who was not involved in the study, said birds provide critical services: They play roles as pollinators, exterminators and fertilizers, and for many, they are simply beautiful to observe.
The fact that bird populations are declining is extremely concerning, Wiedenfeld said.
“Birds are literally the canary in the coal mine,” he said. “The birds are good indicators of what’s going on in the environment.”
This article was originally published on NBCNews.com
No comments:
Post a Comment