A new study has identified more than 500 鈥渓ost鈥� animal species not yet considered extinct but that have remained unseen by anyone for more than 50 years.
While animal extinctions are expected to increase in the coming years, extinction pronouncements remain uncommon due to difficulties in determining when the last individual of a species has died, the study鈥檚 authors suggest.
The study, published in the peer-reviewed journal , offers a first-of-its-kind global evaluation of all terrestrial vertebrate species that are missing but not extinct, identifying a total of 562 lost species (137 amphibians, 257 reptiles, 38 birds and 130 mammals).
Data from the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species on 32,802 species was examined. Of the lost species identified in the study, 13 per cent (75 species) are listed as 鈥漰ossibly extinct鈥� by the IUCN.
Researchers note that the existence of such species may become increasingly problematic, as their presence may generate confusion in conservation priority efforts and our understanding of extinction rates.
"We hope this simple study will help make these lost species a focus in future searches,鈥� said Gareth Bennett, an undergraduate student at Simon Fraser University who is credited with much of the data combing in the study.
The researchers suggest future survey efforts should focus on the identified 鈥渉otspots鈥� in the study such as Indonesia, Mexico and Brazil, where the presence of many specific species is still in doubt.
