One in every five species of reptiles worldwide is facing extinction, study finds
Covering over 10,000 species, study involving Israeli researchers is the most comprehensive of its kind to date; half of all turtles and crocodiles in danger of dying out
Tobias (Toby) Siegal is a breaking news editor and contributor to The Times of Israel.
Israeli researchers have warned of the possible mass extinctions of reptile species around the world, including half of all turtle and crocodile species, mostly due to habitat destruction.
The warning, issued last week, followed an international study involving 52 researchers from around the world, including from Israel, that found that one in every five species of reptiles on earth is facing extinction.
Out of 10,196 reptile species covered by the research, close to 2,000 species are in danger of dying out, said the authors of the study, the first of its kind to address the issue on such a large scope.
The threatened species represent around 15.6 billion years of genetic evolutionary diversity.
The comprehensive study was conducted by the International Union for Conservation of Nature (IUCN) over the span of 18 years and involved Israeli researchers from Tel Aviv University and Ben-Gurion University of the Negev. The alarming findings were published in late April in the peer-reviewed scientific journal Nature.
“In general, the state of reptiles in the world is bad,” Prof. Shai Meiri of Tel Aviv University said in a statement last week. “The biggest threat to reptiles is the destruction of their habitats due to agriculture, deforestation, and urban development,” he noted.
Invasive species also present a major threat and the danger of climate change remains uncertain.
While comprehensive extinction-risk assessments have been available for birds, mammals and amphibians for years, reptiles have been largely neglected in the field until now, the authors of the international study said.
The IUCN aimed to assess the threat of extinction posed to various species according to their specific characteristics, such as reproduction rate, natural habitat and proximity to humans.
Each species was ranked based on its threat level to allow decision-makers and conservation organizations to prioritize protecting the most endangered species.
The state of reptiles is “worse than that of birds and mammals, though not as bad as that of amphibians,” Meiri said, adding that “turtles are in a worse position than lizards and snakes.”
The study found that 58% of all turtle species and 50% of all crocodile species are in danger of becoming extinct. Turtle and crocodile populations are being reduced by hunting, unlike other reptiles species, which are mostly affected by habitat destruction, Meiri said.
By mapping out the threats each species faces on a global perspective, the study offers an opportunity to direct conservation efforts to where they are most needed, the authors said.
“For example, if a particular species is highly threatened in Israel’s Arava desert, but not in the rest of its habitat range that may span the entire Arabian Peninsula, then globally it is not considered a threatened species,” Meiri said.
Despite the study’s global scope, there is still much to be done, according to Dr. Uri Roll from Ben-Gurion University.
“This is important work that forms the initial basis for risk assessment among various reptiles around the world, but is certainly not the end of the story,” he said. “We still lack a lot of information about the various risks facing reptiles. For example, climate change is expected to have significant effects on reptiles. The current assessment that has just been published does not yet include these future threats in its reptile risk assessments.”
“Our world is facing a biodiversity crisis, and severe man-made changes to ecosystems and species, yet funds allocated for conservation are very limited,” Roll said. “It is key that we use these limited funds where they could provide the greatest benefits.”
Moreover, the IUCN assessment left out a number of reptile species that have not been assessed yet or were assigned a data deficient category that excluded their prioritization for conservation.
“However, we can use information on already assessed species to better understand the risks to those not yet assessed,” said Dr. Gabriel Caetano from Ben-Gurion University.
“Species may share physiological, geographic, and ecological attributes (often via shared evolutionary history) that make them more threatened, and experience similar sources of threat when they occur at similar locations,” he said in a statement.
In order to cover the gaps in the IUCN assessment, a group of international researchers has been using advanced machine learning modeling in order to address species that were not assessed by IUCN. Their findings were published in the PLOS Biology science journal.
“In our work, we tried to emulate the IUCN process using predominantly remotely sensed data and advanced machine learning methods. We used species that have been assessed to teach our models what makes a species threatened and then predict the threat categories of unassessed species,” said Caetano, the lead author of the complementary study.
And according to that study, “Unassessed and data deficient reptiles were considerably more likely to be threatened than assessed species.”
Nonetheless, the IUCN offers a first of its kind comprehensive database that will allow decision-makers to understand the specific conservation needs of most reptile species, potentially enabling more effective solutions to the crisis.
The IUCN says its research is “a critical indicator of the health of the world’s biodiversity.”
The group said its Red List of threatened species is used by government agencies, wildlife departments, conservation-related non-governmental organizations, natural resource planners, educational organizations, students, and businesses to formulate policy and conservation efforts.
Among the 142,500 species covered on the IUCN Red List, 40,000 species are threatened with extinction, including 41% of amphibians, 33% of reef-building corals, 26% of mammals and 13% of birds.
