Caiman yacare

Urgent support needed: one in five reptile species is at risk of extinction

A yacare caiman (Caiman yacare).

Reptiles, most of which are predators, are cold-blooded and scaly animals. Their ranks include some of the most deadly and poisonous creatures on Earth, including the saltwater crocodile and the spitting cobra.

Many of these fascinating creatures are feared by people and live in hard-to-reach areas such as swamps. Compared with birds, amphibians and mammals, there is very little data available on the distribution, population size and extinction risk of reptiles. As a result, conservationists in the past have largely helped reptiles indirectly by meeting the needs of other animals (for example, for food and habitat) that live in similar places.

Now a first of its kind global rating of more than 10,000 reptile species (about 90% of the known total), 21% have been shown to need urgent support to prevent them from becoming extinct. But since reptiles are so diverseranging from lizards and snakes to turtles and crocodiles, the threats to the survival of each species are likely equally varied.

Here are five key findings the new study revealed.

Crocodiles and turtles are among the most endangered

More than half (58%) of all crocodile species and 50% of all turtles are at risk of extinction, making them the most endangered among reptiles. This is comparable to the most endangered groups of amphibians and mammals, so reptiles do not fare any better than other animals.

The biggest threats to crocodiles and turtles are hunting and illegal wildlife trade† This trade, often to provide distant customers with pets (or luxury handbags), threatens 31% of turtles. They are also the groups of reptiles most often associated with wetlandshabitats that are under siege worldwide through the development of urban space and agricultural land, but also through climate change.

Conservation works

The tuatara is the sole survivor of an ancient order of reptiles called the Rhynchocephalia, which roamed the Earth along with dinosaurs about 200 million years ago.

To help you understand how isolated this species is in evolutionary terms, rodents belong to a single order that makes up 40% of mammals. Fortunately, populations of this species have stabilized, thanks in large part to the protections they have been given by law since 1895, making it a felony to kill individuals or their eggs or take them from the wild.

Tuataras, which are greenish brown and gray, measure up to 80 cm (32 in) from head to tail and have a spiny crest along their back, were once widespread in New Zealand but became extinct on the main islands about 200 years ago – the at the same time that invasive rats, brought there by European colonizers, were settling. Conservation Effortssuch as captive breeding and targeted reintroductions, have led to tuataras breeding again in the wild in New Zealand’s North Island.

interesting enoughthis species has one of the longest life spans of all reptiles (over 100 years) and a body temperature of about 10 °C (50 °F) – more than 10 °C (18 °F) lower than most reptiles.

Tuatara

Tuataras can continue to breed well past their 100th birthday.

Habitat destruction the biggest threat overall

Loss of residential areacaused by farmland expansion, urbanization and logging, contribute more to the extinction risk of most reptiles than any other factor. Other Major Threats include the displacement of native reptiles by invasive species and hunting. These threats are all man-made and pose a problem for all other groups of animals.

Most Threatened in the Tropics

Southeast Asia, West Africa, Madagascar and the Caribbean are: hotspots for reptiles in danger of extinction. According to the new assessment, some of these areas contain twice as many endangered reptiles as those of other animal groups.

More than half of the endangered reptile species live in woods, where habitat destruction is an imminent threat. The picture is similar for birds and mammals, so preserving forested areas for one group of species will help protect them all.

Climate change

Coldblooded reptiles need to warm up in the sun to function properly. But if they are heated above their optimum temperature, their metabolism is less efficient and they have to go to the shade to cool down.

Rising global temperatures reduce the reptiles’ windows available for daily foraging activities — when it’s neither too cold nor too hot — and narrow their habitable range overall. For some reptile species, the ambient temperature affects the sex of offspring† Cooler temperatures cause many turtle eggs to develop into males, so climate change can see it male turtles are dying out

Turtle lays eggs

A male-female imbalance can prevent populations from reproducing.

What is good for other animals…

Where reptiles are restricted to a certain range – endemic to a single small island, for example – the species is generally so specialized that a conservation effort focused on the needs of that kind is sensible.

But in general, despite being so different, birds and mammals are good surrogates for reptile conservation. This is because the threats imposed on all animal groups are broadly similar. Conservation efforts for one species can benefit everyone.

While this new assessment sheds more light than ever before on the plight of the world’s scaly masses, it nonetheless shares universal lessons for what it takes to preserve Earth’s biodiversity: space and freedom from persecution in a stable climate.

Written by Louise Gentle, Senior Lecturer in Wildlife Conservation, Nottingham Trent University.

This article was first published in The conversationThe conversation


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