One in five reptiles is threatened with extinction mostly caused by humans

Turtles and crocodiles are especially at risk, according to researchers who say there's been a lot more focus on the furry or feathery species of vertebrates for conservation.

Maija Kappler 4 minute read May 3, 2022
Crocodile in the wild on the island of Sri Lanka

The threat to reptiles was previously unknown because they've been excluded from many other extinction studies. GETTY

More than one in five of the world’s reptile species face extinction, according to a comprehensive new study. Primarily aquatic species, like crocodiles and turtles, are among the most vulnerable.

“We would lose a combined 15.6 billion years of evolutionary history if each of the 1,829 threatened reptiles became extinct,” co-the study’s author Neil Cox told The Guardian. “This is evolution that we could never get back. It would be a devastating loss.”

This number is actually smaller than the number of amphibians (40.7 per cent) and mammals (25.4 per cent) that are threatened, but the threat to reptiles was previously unknown because they’ve been excluded from many other extinction studies. This is in part because of their specific conservation needs — many reptile species live in arid regions, the study points out. But it’s actually the reptiles living in forests, not deserts, that face the strongest extinction threats — something the researchers say they didn’t expect.

Reptiles are at risk because of humans

The forces putting reptiles at risk are largely caused by humans and are mostly the same risks threatening other animals: their habitats are being destroyed by agriculture, logging, urban development and invasive species. And while reptiles are less affected than mammals by hunting, urban development remains a large issue.

Climate change also reduces the amount of time reptiles can forage for food, skewing natural sex ratios in some species that have temperature-dependent sex determination. (Turtles, for instance, are born male if the eggs incubate below 27.7 degrees Celsius, and female if they’re above 30.9; a temperature in the middle will yield a mix of male and female babies. A changing climate could decrease the number of male turtles born, making it more difficult for the species to reproduce.)

Researchers used data from 24 countries over a 15-year period, following the International Union for Conservation of Nature’s Red List of Threatened Species to determine the relative threat to 10,196 reptile species.

Of all of those animals, they found that 21.1 per cent faced extinction. Fifty-seven per cent of turtles and 50 per cent of crocodiles are threatened, compared to 19 per cent of squamates, a reptilian group that includes snakes, lizards, iguanas, chameleons and other species that shed their skin and have flexible skulls and jaws. Within the squamate group, iguanas, xenosaurid lizards, and certain kinds of snakes (shield-tailed and tropidophiid) are the most at risk. (Salamanders, which also face a high extinction rate in the 57 per cent range, are often mistaken for reptiles but are actually amphibians, meaning they breathe through gills rather than lungs.)

The reptile species that are threatened are spread out around the world: northern North America, the Rocky Mountains, southeast Asia, West Africa, northern Madagascar, the northern Andes and the Caribbean, the Kalahari, Karoo and Sahara deserts, northern Eurasia.

“Reptiles, to many people, are not charismatic, and there’s just been a lot more focus on the furry or feathery species of vertebrates for conservation,” Bruce Young, chief zoologist and senior conservation scientist at conservation nonprofit NatureServe, which in part led the study, told CNN.

But even when we may not realize it, to a certain extent, our health and wellness does depend on reptiles.

“If we remove reptiles, it could change ecosystems radically, with unfortunate knock-on effects, such as increases in pest insects,” Cox told The Guardian. “Biodiversity, including reptiles, underpins the ecosystem services that provide a healthy environment for people.”

This happens in many different ways, Mike Hoffmann, head of wildlife recovery at the Zoological Society of London and one of the study’s co-authors, also told the paper.

Reptiles “help disperse seeds, especially in island environments,” Hoffmann said. “We’ve also achieved many medical advances from studies of reptiles. Snake venom, for example, has resulted in critical drug discoveries, including for treating hypertension.”

The good news, if there is any, is that implementing many of the measures suggested to help stop the extinction of mammals and other species would likely help reptiles, too.

“We found, surprisingly, that if you set out to protect places where threatened birds, mammals and amphibians live together, you’ll simultaneously protect many more threatened reptiles,” Young said.

The researchers hope people extend the same attention to reptiles as they do the cuter, cuddlier animals.

“The impending loss [of reptile species] could lead to wide-ranging and unforeseen impacts on our environment and our own wellbeing,” Hoffmann said.

Maija Kappler is a reporter and editor at Healthing. You can reach her at mkappler@postmedia.com
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