More than 21% of reptiles at risk of extinction in coming decades, scientists say

Agriculture, logging and urban development pose significant risks to reptiles.

April 28, 2022, 11:00 AM

More than a fifth of the world's reptiles are at risk of extinction in the coming decades due to human activity, according to a new study.

Researchers applied criteria from the International Union for Conservation of Nature Red List of Threatened Species to more than 10,000 species around the world and found that over 21% are at risk -- with nearly 58% of species of crocodiles and and 50% of species of turtles requiring urgent conservation efforts to prevent them from being wiped out from the planet, according to a study published Thursday in Nature.

PHOTO: An endangered Pygmy Stump-tailed Chameleon at the Nosy Mangabe Reserve, north east Madagascar, Dec. 17, 2010.
An endangered Pygmy Stump-tailed Chameleon at the Nosy Mangabe Reserve, north east Madagascar, Dec. 17, 2010.
Nick Garbutt/Future Publishing via Getty Images, FILE

Human activity, such as agriculture, logging, urban development and invasive species, are the main drivers of the threat to reptiles, according to the researchers. While climate change is assumed to be a factor, the exact risk it poses has not yet been determined due to the lack of long-term studies.

"Climate change is a looming threat to reptiles, for example, by reducing thermally viable windows for foraging, skewing offspring sex ratios in species that have temperature-dependent sex determination and contracting ranges," the study states.

PHOTO: An American crocodile is seen during a crocodile tour at the Tarcoles river, in Tarcoles, Garabito municipality, Costa Rica, March 31, 2022.
An American crocodile is seen during a crocodile tour at the Tarcoles river, in Tarcoles, Garabito municipality, Costa Rica, March 31, 2022.
Luis Acosta/AFP via Getty Images, FILE

However, disease does not seem to be a prominent factor for loss of species, as only 11 species of reptiles were found to be at risk of widespread disease, the authors said.

Although previous findings have proposed reptiles to be most at risk in arid environments, such as deserts and scrubland, the researchers found that species inhabiting forests were more threatened, perhaps because of greater exposures to certain threats in forest environments. The study found that 30% of forest-dwelling reptiles are at risk of extinction, compared with 14% of reptiles in arid habitats.

PHOTO: A significant amount of wood chips left by precious wood cutters in the Vohibola forest near the village of Manambato, Madagascar, March 24, 2019.
A significant amount of wood chips left by precious wood cutters in the Vohibola forest near the village of Manambato, Madagascar, March 24, 2019. The Vohibola Forest, one of the last primary forests in eastern Madagascar, has been illegally felled for charcoal production and the sale of rare wood. Some kill the forest animals for food, others sell them as pets.
Rijasolo/AFP via Getty Images, FILE

Threatened reptiles were more concentrated in southeastern Asia, West Africa, northern Madagascar, the northern Andes and the Caribbean, according to the study.

Many of the risks that reptiles face are similar to those faced by other animal groups that have been assessed, such as birds, mammals and amphibians, and reptiles will also benefit from conservation efforts directed toward those other animals, according to the study. The paper, a joint venture by NatureServe, the IUCN and Conservation International, is the first risk-assessment study ever conducted for reptiles, the authors said.

"I was surprised by the degree to which mammals, birds and amphibians, collectively, can serve as surrogates to reptiles,” said Dr. Bruce Young, co-leader of the study and chief zoologist and senior conservation scientist at NatureServe. “This is good news because the extensive efforts to protect better-known animals have also likely contributed to protecting many reptiles. Habitat protection is essential to buffer reptiles, as well as other vertebrates, from threats such as agricultural activities and urban development."

The study also highlighted the biodiversity that would be lost if such a large number of reptiles were to go extinct. If each of the 1,829 threatened reptiles were lost, the world would lose a combined 15.6 billion years of evolutionary history -- including countless adaptations for living in diverse environments, the researchers said.

PHOTO: A Plowshare Angonoka tortoise in the forest of Madagascar, May 8, 2007.
A Plowshare Angonoka tortoise in the forest of Madagascar, May 8, 2007.
De Agostini via Getty Images, FILE

"Reptiles in the study include turtles, crocodiles, lizards, snakes, and tuatara, the only living member of a lineage that evolved in the Triassic period approximately 200-250 million years ago," according to a press release by NatureServe, a wildlife conservation nonprofit.

Urgent and targeted conservation efforts, such as habitat restoration and controlling invasive species, are needed to restore the populations of many reptile species, the researchers said.

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