Just over a fifth of the reptiles existing today are at risk of disappearing, indicates the first global analysis on the subject. The study, which evaluated about 10,000 species (almost all the animals in the group), brings at least good news: it will not be necessary to think about exclusive protection areas for them when trying to reverse this situation. Reserves created to protect mammals, birds and other vertebrates are also likely to be sufficient to prevent the extinction of most reptiles.
The data have just come out in an article in the scientific journal Nature. The work is signed by an international team with dozens of scientists, including three Brazilians: Marcio Martins and Cristiano de Campos Nogueira, both from the Department of Ecology at USP, and Guarino Colli, from the Department of Zoology at UnB (University of Brasília).
Among terrestrial vertebrates, reptiles ended up being last in this kind of comprehensive survey—similar data on birds, mammals, and even amphibians had been available for more than a decade. And the reason for the delay is not surprising.
“It was really a lack of money”, summarized Martins in an interview with Sheet. Although there were plans to start the initiative since 2004, the work ended up dragging on due to funding difficulties, which ended up hindering the intense work of workshops with specialists necessary to gather the data (in total, there were 48 meetings, with the participation of almost a thousand researchers ).
Luckily, Brazil had already done its homework on its own in 2014, analyzing the conservation status of its approximately 800 native species of reptiles. “A new Brazilian list is about to come out, but it changes practically nothing in relation to the previous one”, says the USP researcher.
Of the 10,196 species analyzed, 21.1% fit into one of the three extinction risk categories (vulnerable, threatened or critically endangered). The group’s situation is less serious than that of amphibians and mammals, but more worrying than that of birds (see infographic). Brazilian species are, in general, within the world average in terms of extinction risk, while Southeast Asia, West Africa and the Caribbean are among the regions with the highest proportion of threatened reptiles.
Before the survey was carried out, it was suspected that the species at risk were particularly common in more arid and open environments, from deserts to savannas.
“There are several reptiles that are very specialized for life in these habitats, and this specialization, in theory, increases vulnerability to extinctions. But what happens is that, in fact, many of these more arid regions were less affected by human pressure. At the same time, the tropical forests have been very messed up, and it is in them that the threatened reptiles are concentrated.” In the Brazilian case, this is especially true in the Atlantic Forest and, increasingly, in the Amazon.
Taking this into account, the loss of forest habitats due to agricultural expansion, advancing urban areas and logging tops the list of threats. Next comes the action of invasive species and hunting.
This last danger can take on different contours. In Brazil, an emblematic case, according to Martins, is the jararaca-ilhoa (Bothrops insularis), a snake adapted to life in trees that exists only on an island off the coast of São Paulo (as both its popular name and its scientific designation suggest).
It seems that the animal has lost half its population in recent decades, at least in part because of the illegal pet trade. The most threatened reptiles, however, are turtles, alligators and crocodiles, especially because of culinary consumption. Almost 60% of the so-called Testudines (turtles, tortoises and tortoises) and half of the Crocodylia (alligators, crocodiles and gharials) are at risk of disappearing.
Nevertheless, the fact that there is a good overlap between areas that harbor at-risk reptiles and those that have other terrestrial vertebrates in the same situation brings some encouragement. “There were fears that we would have to go after the damage, due to the fact that there was not yet the same assessment that was made for the other groups. But, it seems, it is possible to protect all of them reasonably well in the same conservation units. “, ponders Martins.
