Lost but not forgotten: a new nomenclature to support a call to rediscover and conserve lost species
BARNEY LONG and JON PAUL RODRÍGUEZ
Because we are experiencing a sixth mass extinction event (Jablonski, 1995; Ceballos et al., 2010), caused by the action of humans, this era is known as the Anthropocene (Crutzen & Stoermer, 2000). With extinction rates probably a thou- sand times higher than the background rate (Pimm et al., 2014), we must take meaningful action to avert extinctions. For an animal, plant or fungus to be categorized as extinct on the IUCN Red List of Threatened Species, there should be ‘no reasonable doubt that the last individual has died’ and that ‘exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual.. .over a time frame appropriate to the taxon’s life cycle and life form’ (IUCN, 2012). Of the estimated 8.7 million eukaryotes (Mora et al., 2011), c. 1.8 million are known to science (Fisher, 2019). Of these, there is greater uncertainty in cat- egorizing as extinct those that are less well known, harder to detect and perceived as less charismatic. Speciesmay be slid- ing into extinction without us knowing, as only 142,577 have been assessed for the Red List. Of these, 40,084 (28%) are considered threatened with extinction (IUCN, 2021). Most of the c. 1.65 million whose extinction risk has yet not been assessed probably have less appeal to our emotions or culture, are hard to observe or photograph, or do not have common names we can relate to. There is a subset of known species that have simply
dropped off science’s radar. These are the so-called lost spe- cies that have not been seen in the wild for long periods of time and are not under human care at any ex situ organiza- tion such as a zoo, aquarium or botanical garden. Lacking knowledge of where these species persist hinders conserva- tion action. Here, we call for an enthusiastic and energetic expansion of efforts to find such species, so that their con- servation needs can be addressed (e.g. through threat reduc- tion and population recovery) before they quietly slide into extinction. The term lost species has not been formally defined but is
widely used to mean different things. It may refer to extinct species (Campbell et al., 2016; Hirsch, 2017; de Massol de Rebetz, 2020) or to those not seen for a period of time (Twomey & Brown, 2008; Cottee-Jones et al., 2013; Silcock
BARNEY LONG (Corresponding author,
orcid.org/0000-0002-9747-6042,
blong@rewild.org) Re:wild, P.O. Box 129, Austin, Texas 78767, USA
JON PAULRODRÍGUEZ (
orcid.org/0000-0001-5019-2870)IUCN Species Survival Commission, Provita, and Venezuelan Institute for Scientific Investigation (IVIC), Caracas, Venezuela
et al., 2020). So-called missing or long-lost species are also part of the lexicon on the subject. Here, to help catalyse conservation action and prevent extinctions, we propose a nomenclature that distinguishes the various terms and aims. A lost species is one not confirmed alive by photographic,
audio or genetic information for over 10 years in the wild and has no ex situ population under human care. We con- sider under human care the maintenance of whole, living specimens, not cryopreserved samples in a biobank. A spe- cies’ lost status is independent of its category on the IUCN Red List of Threatened Species but has not met the con- ditions to be classified as Extinct or Extinct in the Wild. Although a simple definition, it is applicable to all taxa irre- spective of life traits or the biome in which they live. Some have called for a shorter time period to consider a
species lost, as much can change in 10 years.Werecommend using missing species for those not seen in the wild and not held under human care for .5 years but ,10. The term long-lost has also been applied (Villarroel et al., 2014; David & Davis, 2017), and we propose a time span of 50 years for these species. By consistently using these terms we identify a pathway from missing to lost to long-lost that facilitates the catalysis of stage-specific actions to pre- vent species identified as missing from becoming lost and subsequently becoming long-lost. Although not universally true, it is likely that the longer a
species is lost and themore extensive the search effort with- out rediscovery, the higher the likelihood it is extinct. The missing–lost–long-lost pathway and efforts to find a species may help determine whether it is extinct or not, but extinc- tion is not an automatic outcome, as species can remain hid- den, leading to difficult decisions on when and how to call a species extinct (Roberts & Fisher, 2020). The decision to designate a species extinct should lie with the appropriate IUCN Red List Authority (SSC, 2020), and be based on evi- dence provided by relevant experts on that species and the species’ distribution. Species can be lost for many reasons. Some are naturally
rare or cryptic and so are hard to document conclusively (e.g. de Lírio, 2018; Paglia et al., 2022), others have had their numbers reduced to such low levels that finding them is difficult (e.g. Lee et al., 2008;Richmondetal., 2022). Some have not been searched for since their discovery (e.g. Edwards et al., 2018), and others have become lost following reclassification. Look for them and you may find them is the premise of the Search for Lost Species launched by Re:wild in 2017
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (
https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. Oryx, 2022, 56(4), 481–482 © The Author(s), 2022. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605322000618
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