Explaining REPAD's Conservation Status Categories

By Branden Holmes (Surroundx) on August 12, 2012

One of the planned future features of REPAD will be our own unique status categories. However this system will not be implemented until basically all potentially recently extinct species have been entered into the database. This itself is a significant task and I have not yet entered a single recently extinct plant into the database. This article is therefore more to test the waters regards the appropriateness of our own idiosyncratic status categories, and to receive feedback from visitors to the database regards any possible improvements which could be made before implementing this system.

The International Union for Conservation of Nature and Natural Resources, more commonly known by its shortened acronym "IUCN", is the world's largest conservation organization, consisting of hundreds of scientists from dozens of countries. One of the many tasks which the IUCN has undertaken is to evaluate the current conservation status of the world's flora and fauna. The results of this assessment are available online as the Red List of Threatened Species, or in hardcopy format through appropriate channels. However, as the IUCN is a conservation organization and thus specializes on conserving species which still survive either in the wild or in captivity, they only have two categories which identify a taxa as extinct. These two categories: 'extinct' and 'extinct in the wild', are thus unsuitable when identifying potentially recently extinct species. This is evidenced by several taxa formerly evaluated as being globally extinct having been rediscovered. Thus, even if a taxon is listed as extinct by the IUCN there is no guarantee that it is actually extinct. However as the IUCN is the most authoritative source in the world on such matters their information is regarded as definitive. Thus hardly anybody would 'waste their time' seeking a taxon which the IUCN has declared to be extinct. It would be a waste of resources, as well as multiple man hours, and most importantly, funding.

As an antidote to this situation, because many species which have been declared extinct in fact almost certainly are not, and yet will go extinct in the meantime because nobody has conducted any surveys for these species, I hope to rectify the situation by proposing categories which probabilify the extinction of "missing" taxa, and hence argue that our documentation of extinct should be far more rigorous given the stakes: the extinction of species thought to be extinct, or, the "Romeo Error":

Status Category Explanation Corresponding Probability of Extinction
A Almost certainly still extant 0-10%
B Best considered as extant 10-40%
C Could be either 40-60%
D Data indicates it is extinct 60-99%
DD Data Deficient Not applicable
E Extinct 100%
EW Extinct in the wild (survives in captivity) A, B, C, D, DD, or E attached to 'EW'. E.g. EW 'E' (100% probability of extinction in the wild)
FE Functionally extinct Not applicable
W Whether it survived until 100ka is unknown  Not applicable

Given the fact that even species which are believed to be extinct can still persist in isolated pockets of its former habitat, e.g. the Cebu Flowerpecker (Dicaeum quadricolor), a taxon should only be classified as globally extinct, or extinct in the wild, if there is no suitable habitat remaining, and thus no possibility whatsoever that the taxa is still extant. This is important because we should not give up on rediscovering a species until it is known for certain that it does not survive.

The Tasmanian Tiger: A Case Study

An excellent example of a species which is widely regarded as extinct, including being officially declared extinct on September 7, 1986, yet for which much suitable habitat still exists, as well as many thousands of purported sightings and even some supposed photographic and possibly video documentation, is the thylacine or Tasmanian Tiger. The last confirmed individual outside of captivity was captured by Elias Churchill in 1933 and taken off to the Hobart Zoo. And either this same individual, or one captured previously, died on the 7th of September, 1936. Since that time, despite many claimed sightings in the years immediately after "Benjamin" died, including by trappers who knew exactly what a thylacine looked like and the way it behaved, no unambiguous evidence of its persistence has ever been proffered up. However, despite all of this negative evidence, Tasmanian is quite sparsely populated, with much suitable habitat still intact. It has historically also been a very shy animal, with encounters with the species being rare over the entire period which it overlapped with European man. Thus it would be unwise to claim that there is no chance that the species still persists. In fact, given all of the positive evidence (i.e. plenty of suitable habitat, plenty of witnesses, photos and video evidence, scats, hairs, footprints), some people would say that there is actually a good chance that the species still survives.


Although there is a global financial crisis currently underway, with many governmental and not-for-profit organizations and clubs fighting for funding, we cannot in good conscience ignore the fact that some species are going extinct as we speak because everybody thinks that they are already extinct. We need to allocate at least some funding towards expeditions to rediscover putatively extinct species. Otherwise we end up being hypocrites: fighting to conserve species while ignoring the plight of others all because we think it is too late to save them, even though our basis for believing them to be extinct certainly does not necessarily lead to that conclusion.

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About Branden Holmes
I am a freelance writer with a special interest in conservation biology.

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