Missing for Decades: Researchers Identify Over 500 Species As “Lost”

Researchers have reviewed the data of over 32,000 species and identified 562 of those species as “lost.” 75 of these 562 lost species are categorized as “possibly extinct.”

A new study has identified 562 lost species

An international study provides the first worldwide assessment of all terrestrial vertebrate species that have not been declared extinct and finds more than 500 ‘lost’ species—those that have not been observed by anybody in more than 50 years.

Researchers examined data from the International Union for Conservation of Nature’s Red List of Threatened Species (IUCN Red List) of 32,802 species and identified 562 lost species. On May 16th, 2022, their results were published in the journal Animal Conservation.

Black-browed babbler, a songbird species endemic to Borneo that went unrecorded for 172 years before being rediscovered in 2020. Credit: Panji Akbar

Extinct is defined by the IUCN Red List as “when there is no reasonable doubt the last individual of a species has died,” which can be hard to prove. According to Arne Mooers, a biodiversity professor at Simon Fraser University and research co-author, the Red List classifies 75 of the 562 lost species as ‘probably extinct.’ The presence of numerous species with unknown conservation status may become more problematic if the extinction crisis worsens and more species disappear, according to the researchers.

Since 1500, 311 terrestrial vertebrate species have been declared extinct, indicating that 80% more species are deemed lost than are pronounced extinct.

Reptiles led the way with 257 species considered lost, followed by 137 species of amphibians, 130 species of mammals, and 38 species of birds. Most of these lost animals were last seen in megadiverse countries such as Indonesia (69 species), Mexico (33 species), and Brazil (29 species).

Miles’ robber frog (Craugastor milesi), is endemic to Honduras and thought to be extinct but was rediscovered in 2008. Credit: Tom Brown

While not surprising, this concentration is important, according to researchers. “The fact most of these lost species are found in megadiverse tropical countries is worrying, given such countries are expected to experience the highest numbers of extinctions in the coming decades,” says study lead author Tom Martin from the UK’s Paignton Zoo.

Mooers, who anchored the study, says: “While theoretical estimates of ongoing ‘extinction rates’ are fine and good, looking hard for actual species seems better.”

Gareth Bennett, an SFU undergraduate student who did much of the data combing, adds: “We hope this simple study will help make these lost species a focus in future searches.”

The authors suggest that future survey efforts concentrate on the identified ‘hotspots’ where the existence of many particular species remains in question. More funding would be needed to support such hotspot-targeted fieldwork to either rediscover lost species or to remove the reasonable doubt that a particular lost species does, in fact, still exist.

Reference: “‘Lost’ taxa and their conservation implications” by T. E. Martin, G. C. Bennett, A. Fairbairn and A. O. Mooers, 16 May 2022, Animal Conservation.
DOI: 10.1111/acv.12788

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