Extreme heat threatens tropical birds, even in untouched forests, warn scientists

From the rainforests from Central and South America to the savannas of Northern Australia, the equatorial regions of the world housing thousands of unique bird species, from Aras to Toukans to Kolibris, which thrive in hot and moist environments.

But when climate change accelerates, tropical regions see ten times as many dangerously hot days than 40 years ago, which endangers the survival of some of the world’s most colorful birds, as new research results show.

Between 1950 and 2020, extreme heat events reduced the tropical bird populations by 25% to 38%, according to a study published in the Nature Ecology and Evolution magazine.

The study shows that extreme heat events are a “main driver of the species loss” – which can explain why even bird populations are disappearing in some of the flawless corners of the earth, said James Watson, professor of natural sciences at the University of Queensland and one of the study authors.

“It really points out that we have to sort greenhouse gas emissions because these extreme heat scenarios will increase over time,” said Watson.

Watson and his colleagues analyzed more than 90,000 scientific observations from more than 3,000 bird populations and voted in the daily weather records from 1940 to see how bird populations reacted to extreme weather events, including precipitation and heat waves.

They tested their results against data on human industrial activity in order to concentrate specifically on the effects of climate change.

The scientists found that exposure to heat (temperatures that exceed the 99th percentile) led to a reduction in bird populations in widths below 55 degrees to the north or south, the most extreme effects in the tropics felt that widths below 23 degrees.

The authors found that the increase in heat extremes was more harmful to birds than the annual average temperature increases caused by climate change.

Extreme warmth represents a severe threat to tropical birds

The idea that the bird populations are falling steeply is not new – a study in 2019 showed that bird populations in the USA and Canada have dropped by 30% since 1970, which means a loss of almost 3 billion birds.

Much of this loss, however, was attributed to more direct human effects such as the loss of habitats from agriculture, logging and mining or even the construction of collisions.

The study underlines the threat of extreme warmth for birds in tropical regions and helps to explain why birds also die in distant and protected areas, in whose biological diversity they are typically taken into account.

In two undisturbed rainforests in Panama and in the Amazon, the bird populations decreased by more than 50% between 1977 and 2020 and between 2003 and 2022.

If birds are exposed to extreme heat, you can become hyperthermous, where your body temperature is increased to a dangerous level. Since birds cannot sweat under these conditions, they can start to whine or to expose more from your skin to try to release the heat.

The bird can be dehydrated or disoriented and, in some cases, lose consciousness and fall from its tie rods. Exposure to extreme heat can also cause organ damage in the event of birds and hinder their reproductive capacity.

Part of what makes the tropics so important areas for biological diversity is also what makes it particularly fragile for climate change.

“It is almost the perfect storm,” said Golo Maurer, the director of the bird protection strategy at BirdLife Australia.

In tropical areas you will find species with small populations that have found your niche in a very narrow temperature tape, said Maurer, who was not involved in the study. “This in turn drives amazing variety.”

But when the temperatures go beyond these comfortable ligaments, tropical birds have difficulty adapting, said Watson.

“You have far smaller population groups and their evolutionary capacity is much, much smaller,” said Watson.

“Another wake -up call”

Maurer said the study shows that “we cannot just sit back” and assume that species will be safe because they are in protected areas.

“Climate change is so omnipresent that it also affects these areas,” he said.

Maurer said he noticed how climate change in his tropical home in North Queensland, Australia, has an area of an area known for its biodiversity with a large number of endemic birds.

For example, BirdLife’s volunteers had to go to higher increases to recognize Golden Bowerbirds, small yellow birds with a small reach and to live in the rainforest in Queensland, said Maurer.

Watson said that the study was to serve as “another wake -up call that greenhouse gas emissions and climate change are a major problem for biological diversity”.

“We have to reduce climate change as a main strategy because we will lose a large number of species in the tropics if we don’t.”

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