生態学：爬虫類の絶滅リスクの評価

Over 21% of reptile species are threatened with extinction, suggests a global assessment of more than 10,000 species published in Nature. The findings indicate that some reptiles, including many species of crocodiles and turtles, require urgent conservation efforts to prevent extinctions.

Comprehensive extinction risk assessments are available for birds, mammals and amphibians, but have been lacking for reptiles. Conservation strategies for reptiles have so far relied on International Union for Conservation of Nature (IUCN) Red List criteria and distributions of other animals to inform policy and priorities.

Bruce Young and colleagues applied the IUCN Red List criteria to reptiles to examine extinction risks for reptiles globally. Of the 10,196 species assessed, they found that at least 1,829 (21%) of species were threatened with extinction (categorized as being vulnerable, endangered or critically endangered). Crocodiles and turtles are among the most at-risk species, with around 57.9% and 50.0% of those assessed being under threat, respectively. The authors indicate that factors including agriculture, logging, urban development and invasive species are drivers of the threat to reptiles, although they acknowledge that the risk that climate change poses is uncertain. Although previous predictions have proposed reptiles to be most at risk in arid environments (where they are highly diverse), Young and colleagues found that species inhabiting forests were more threatened — perhaps because of greater exposures to certain threats in forest environments.

The authors highlight that many of the risks that reptiles face are similar to those faced by other animal groups, and suggest that conservation efforts to protect these groups — including habitat restoration and controlling invasive species — may have also benefited reptiles. However, they caution that some reptiles do require urgent conservation efforts to prevent extinctions.