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New study: why are some species rediscovered while others remain lost?

By 18th January 2024News

One third of remaining lost mammal species are restricted to small areas, such as islands, where they are particularly vulnerable to extinction. The Bramble Cay Melomys (Melomys rubicola) was once considered to be a lost species, but has now been declared extinct. Source: State of Queensland/Wikimedia.

Lost species are those that have been lost to science for at least a decade. Many small mammals haven’t been surveyed since their initial discovery over 100 years ago, remaining unrecorded today. Some potentially go extinct before we have a chance to find them, whilst others are thankfully ‘rediscovered’ through targeted campaigns and fieldwork. Such rediscovered species tend to have restricted ranges and remain highly threatened. Thus, rediscoveries have important conservation implications.

But why is it that some species are rediscovered and others aren’t?

New research, led by Thomas Evans (Freie Universität Berlin) with co-authors including the SMSG’s Co-Chairs, Thomas Lacher Jr and Rosalind Kennerley, has attempted to understand why certain tetrapod species are rediscovered but others not.

Creating a database of lost and rediscovered tetrapods, the researchers examined patterns in distribution and factors influencing rediscovery, such as body mass, habitat requirements and influence of human activities.

What does this mean for small mammals?

Nearly half (49%) of lost mammal species are rodents, and the research suggests that there are more lost and fewer rediscovered rodents than would be expected by chance.

Lost rodents, like other small taxa, might be perceived to be uncharismatic and are thus neglected in terms of conservation effort. They may also be hard to find – some are nocturnal or occupy habitats that are difficult for researchers to access. Whatever the reason, we need to find ways to improve efforts of searching for these neglected lost species, before it’s too late.

Read more in The Conversation article here, and find the full paper linked below:

Lindken, T. et al. (2024) What factors influence the rediscovery of lost tetrapod species? Global Change Biology 30, 1,

Author: Abi Gazzard (SMSG Programme Officer)