by From the rainforests from Central and South America to the savannas of North Australia, the equatorial regions in the world are the home base of thousands of unique bird species, from macaws to toucans to hummingbies, thrive in hot and humid environments.
But while climate change is accelerating, tropical regions see ten times the number of dangerously warm days than 40 years ago, the survival of some of the world’s most colorful birds, new research shows.
Between 1950 and 2020, extreme heat events reduced tropical bird populations by 25% to 38%, published according to a study in the journal Nature Ecology and Evolution.
The study shows that extreme heat – events are a “primary cause of loss” – that can explain why even bird populations in some of the most unspoilt corners of the earth, said James Watson, a professor of nature conservation science at the University of Queensland and one of the authors of the study.
“It really points to the fact that we have to solve the emissions of greenhouse gases, because these extreme heat scenarios will increase over time,” Watson said.
Watson and his colleagues analyzed more than 90,000 scientific observations of more than 3000 bird populations and corresponded to daily weather records from 1940, to see how bird populations responded to extreme weather conditions, including rainfall and heat waves.
They tested their findings against data on human industrial activity to focus specifically on the effects of climate change.
The scientists discovered that exposure to extreme heat (temperatures that exceeded the 99th percentile) led to a reduction of bird populations on wide -legs under 55 degrees north or south, with the most extreme effects in the tropics, which means wide -growning under 23 degrees.
The authors discovered that the increase in extreme heat was more harmful to birds than the annual average temperature rises caused by climate change.
A Collared Aracari Toucan on the Moss branch in the forest, Boca Tapada, Costa Rica. – Ondrej Prosicky/image broker/Shutterstock
Extreme heat is a serious threat to tropical birds
The idea that bird populations decrease steeply is not new – a study from 2019 found that bird populations in the US and Canada have fallen by 30% since 1970, which means a loss of nearly 3 billion birds.
However, much of this loss is attributed to more direct human effects, such as habitat loss due to agriculture, logging and mining, or even building collisions.
The study underlines the threat that extreme heat poses for birds in tropical areas and helps explain why birds die, even in remote and protected areas, usually considered ports of biodiversity.
In two undisturbed rain forests in Panama and the Amazon, bird populations fell by more than 50% for the majority of species between 1977 and 2020 and between 2003 and 2022 respectively, according to the study.
When birds are exposed to extreme heat, they can become hyperthermisch, whereby their body temperature has been increased to a dangerous level. Since birds cannot sweat, they can start panting or exposing more of their skin under these circumstances to try to release the heat.
The bird can become dehydrated or disoriented and in some cases lose consciousness and fall out of their perches. Exposure to extreme heat can also cause organ damage in birds and hinder their reproductive capacity.
Part of what makes the tropics of such important areas for biodiversity is also what makes them particularly vulnerable to climate change.
“It is almost the perfect storm,” said Golo Maurer, the director of the bird retention strategy at Birdlife Australia.
In tropical areas you will find species with small populations that have found their niche in a very narrow tire of temperatures, said Maurer, who was not involved in the study. “This in turn stimulates amazing diversity.”
But when the temperature goes beyond these comfortable tires, tropical birds struggle to adjust, Watson said.
“They have much smaller populations and their evolutionary capacity is much, much smaller,” said Watson.
An ARA can be seen in the Santa Sofia Uchuma community, near Leticia, Amazonas Department, Colombia, on November 19, 2020. – Raul Arboleda/AFP/Getty Images
‘Another wake-up call’
Maurer said that the study shows: “We can’t just lean back” and take that species will be safe because they are in protected areas.
“Climate change is so penetrating that it will also influence those areas,” he said.
Maurer said he noticed how climate change birds in his tropical home base of Noord -Veensland, Australia, an area that is known for its biodiversity with a large number of endemic birds.
For example, the voluntary observers of Birdlife have to go to higher heights to spot gold Bowerbirds, small yellow birds that have a small reach and live in the rainforest in Queensland, Maurer said.
Watson said that the study should serve as “another wake-up call that greenhouse gas emissions and climate change are a major problem for biodiversity.”
“We must reduce climate change as a primary strategy, because we will lose a huge number of species in the tropics if we don’t.”
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