Decades Of Data Show Bird Populations Collapsing Even In Remote, Pristine Regions; Now, Warming Looks Like The Cause
EDIT
At other remote sites around the world, scientists had been starting to observe similar trends. In Brazil, the Biological Dynamics of Forest Fragments Project (BDFFP) is an ecological study located deep in primary Amazon forest, unreachable by road. These regions hold some of the oldest living forests on the planet – they evaded the ice age events that remade forests in the US and Europe with the growth and retreat of glaciers. “In the Amazon, we’ve had pockets of stable forests over millions of years,” says ecologist Jared Wolfe, one of the project’s research scientists. “The site is truly amazing.” But in 2020, when researchers there compared bird numbers with the 1980s, they found a number of species in deep decline. At another site in Panama, scientists working in a 22,000-hectare (54,000-acre) stretch of intact forest had been gathering bird data since the mid-1970s. By 2020, their numbers had gone off a cliff: 70% of species had declined, most of them severely; 88% had lost more than half their population. At some sites, scientists are beginning to observe “almost complete community collapse”, says Wolfe. “This is occurring in pristine environments, which is really unsettling.”
For decades scientists have been trying to understand what is going on. Blake and collaborator ornithologist Bette A Loiselle published their first paper documenting the declines in 2015, but could not definitively say what was causing them. They tested birds for disease and parasites, and found no clear links. They considered the possibility that an unknown toxin or pollutant had seeped in – but there was no evidence of that. “I suspect whatever is causing these declines is something much more widespread,” Blake says. “It would not be something specific to the Tiputini area.” The most likely answer, they concluded, was the climate crisis. “There’s very little else – at least that I know of – that has such large scale worldwide impacts,” says Blake.
A decade later, their instincts are proving correct. This week, Wolfe and collaborators published new work directly linking rising temperatures to bird declines. Their research, published in Science Advances, tracked birds living in the forest understory at the BDFFP against detailed climate data. They found that harsher dry seasons significantly reduced the survival of 83% of species. A 1C increase in dry season temperature would reduce the average survival of birds by 63%. Exactly how the heat is causing bird numbers to decline is tricky to pinpoint, Wolfe says, but “these birds are intrinsically linked to small, small changes in temperature and precipitation”. One of the most immediate ways a heating planet hurts wildlife is by putting them out of step with their food sources: when fewer insects survive dry seasons, or leaves bloom and fruit ripens at different times, birds find themselves unable to forage and feed their young. Their nests begin to fail. Within a few generations, their numbers fall.
The losses documented in these remote stations have implications far beyond birds. “The idea has always been that if you have huge expanses of forest, then that’s going to protect everything,” Blake says. “And, well, it does protect a lot of things. But apparently not everything.”
EDIT
https://www.theguardian.com/environment/2025/jan/30/birds-dying-pristine-amazon-climate-crisis-aoe
= new reply since forum marked as read
