One in five reptile species is threatened with extinction
Reptiles, the majority of which are predators, are cold-blooded and scaly animals. Their ranks include some of the deadliest and most venomous creatures on Earth, including the saltwater crocodile and the spitting cobra.
Many of these fascinating creatures are feared by humans and live in hard-to-reach areas such as swamps. Compared to birds, amphibians and mammals, very little data is available on the distribution, population size, and extinction risk of reptiles. As a result, wildlife conservationists have largely helped reptiles indirectly in the past by meeting the needs of other animals (for food and habitat, for example) living in similar places.
Now a first of its kind global evaluation of more than 10,000 species of reptiles (about 90% of the known total) revealed that 21% 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 to be just as varied.
Here are five important findings revealed by the new study.
Crocodiles and turtles among the most endangered
Well over half (58%) of all crocodile species and 50% of all turtles are threatened with extinction, making them the most endangered reptiles. This is comparable to the most endangered groups of amphibians and mammals, so reptiles fare no better than other animals.
The greatest threats to crocodiles and turtles are hunting and illegal wildlife trade. This trade, often intended to supply remote customers with pets (or luxury handbags), threatens 31% of turtles. They are also the groups of reptiles most frequently associated with swampshabitats that are globally beleaguered by the development of urban space and agricultural land, as well as climate change.
The tuatara is the sole survivor of an ancient order of reptiles called Rhynchocephalia, which roamed the Earth alongside dinosaurs around 200 million years ago.
To help you understand how evolutionarily isolated this species is, rodents belong to a single order that makes up 40% of mammals. Fortunately, the populations of this species have stabilized, largely thanks to the protection they have enjoyed under the law since 1895, which makes it an offense to kill individuals or their eggs or to collect them from the wild.
Tuataras, which are greenish-brown and grey, measure up to 80cm (32 inches) from head to tail and have a spiny crest along their backs, were once widespread throughout New Zealand but became extinct on the main islands about 200 years ago – the at the same time as invasive rats, brought by European colonizers, settled there. Conservation effortssuch as captive breeding and targeted reintroductions, have meant that tuataras are breeding again in the wild on New Zealand’s North Island.
interesting waythis species has one of the longest lifespans of any reptile (over 100 years) and a body temperature of around 10°C (50°F) – over 10°C (18°F) lower than most reptiles.
Habitat destruction is the biggest global threat
Habitat losscaused by agricultural land expansion, urbanization and logging, contributes more to the risk of extinction for most reptiles than any other factor. Other major threats include displacement of native reptiles by invasive species and hunting. These threats are all of human origin and pose a problem for all other groups of animals.
Most endangered in the tropics
Southeast Asia, West Africa, Madagascar and the Caribbean are hot spots for endangered reptiles. According to the new assessment, some of these areas contain twice as many endangered reptiles as other animal groups.
More than half of endangered reptile species live in the forests, where habitat destruction is an imminent threat. The situation is similar for birds and mammals, so conserving forest areas for one group of species will help protect them all.
in cold blood 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 must seek shade to cool down.
Rising global temperatures are shrinking the windows reptiles have to forage on a daily basis – when it’s not too cold but not too hot either – and reducing their habitable range overall. For some species of reptiles, the ambient temperature influences the sex of offspring. Cooler temperatures are causing many turtle eggs to turn into males, so climate change could see male turtles die.
Which is good for other animals…
When reptiles are restricted to a particular range – endemic to a single small island, for example – the species is usually so specialized that a conservation effort focused on needs of this species is cautious.
But overall, birds and mammals are good substitutes for keeping reptiles, despite being so different. Indeed, the threats imposed on all groups of animals are broadly the same. Conservation efforts for one species can benefit all.
While this new assessment sheds more light than ever on the plight of the world’s scaly masses, it nonetheless shares universal lessons about what is needed to preserve Earth’s biodiversity: space and freedom from persecution in a stable climate.
Written by Louise Gentle, Lecturer in Wildlife Conservation, Nottingham Trent University.
This article was first published in The conversation.