Conservation Status is Onto-Epistemic
By Branden Holmes
The IUCN RedList is one of the world's most cited conservation-orientated resources. But as powerful a tool as it is, it also, like almost anything, has its shortcomings. Often assessments are not updated in a timely matter, taxa are not (yet) assessed at all, and then taxa which were rediscovered years ago are sometimes still listed as 'Extinct'. But even if the RedList were perfect, even if all available information were compiled and used as the basis of all conservation assessments, it would still not be perfect. That is because conservation status is onto-epistemic, not ontic.
This website is an attempt to compile all available information on every single taxon that meets any two (or more) of a small number of criteria:
Necessarily must meet this criterion:
- Believed to have survived until the start of the Late Pleistocene (c.126ka)
Meets at least one of the following additional criteria:
- Believed to be extinct, probably extinct, or is "missing" (50% chance it is extinct, or greater)
- Believed to have been rediscovered, either globally or in the wild, after meeting the above criterion
- Currently believed to be extinct in the wild
- Formerly considered to be a valid taxon/breed/variety that meet at least one of the above criteria
Notice that every single criterion mentioned is actually predicated upon human beliefs and knowledge (i.e. epistemology), rather than actual ontic status. That is to say, the conservation status assessment of any given taxon is derived not from any automatically corrective correspondence with reality (to mention only one of many theories of truth). Rather it is from data gathered by the world's humans. Some or all of that data may be inaccurate, misleading or just plain wrong. We humans are subjective beings, the fallible genetic and experiential products of a truly digital world (i.e. the biological world, where DNA is essentially digital code) in which the inexorable increase of entropy (as a rule of thumb) in the wider physical universe has been temporarily reversed provincially1.
The Thylacine: A Case Study
At the start of the Holocene epoch 11.7ka, the thylacine is known to have existed in what is modern day New Guinea, mainland Australia, Tasmania as well as some other small Australian islands (i.e. Kangaroo Island, South Australia and Hunter Island, Tasmania). We know this because their palaeontological and recent remains have been found there. But just because we have not found their remains in other places does not mean that they were necessarily limited geographically only to these areas. Nor is there a guarantee that the youngest remains that we have for the species in each of these areas represents the very last individual/s inhabiting those areas.
In Tasmania in particular, since the species survived there so recently (until at least 7 September, 1936), and assuming that it is now sadly extinct there, the most recent Tasmanian remains are far more likely to be of some of the very last individuals than, say, those from New Guinea known from the mid-Holocene (c.5-5.5ka). Now of course, barring what would be the truly remarkable discovery of an entirely new population of living thylacines, I previously made the assumption, as part of my argument, that the thylacine is now extinct in Tasmania. Of course this is not necessarily the case.
The general scientific opinion is that the species is indeed wholly extinct throughout its former range. However, that statement is qualified for good reason. Not even the most ardent critic of claims of an extant population are claiming that it is impossible for the species to still exist. Rather, the thylacine almost certainly (or probably, or likely etc.) does not exist. There can be no reasonable doubt that the thylacine once existed, whatever its current fate. Thus it cannot be the case that thylacines cannot survive because it is impossible for them to do so on the basis that they are biologically impossible. Nor even that insufficient habitat remains for them. One trip to Tasmania (or just about anywhere in New Guinea, and indeed many places on the mainland of Australia) will quickly dispel that notion.
Therefore, when assessing the conservation status of the species, the aim is to try and model the most accurate representation of the species' actual ontic status in the wild and/or captivity. This involves things like the most recent record of the species, estimates of population sizes at various times, the methodological appropriateness of expeditions/surveys, etc. Notice that it is an implicit assumption in all of this that the species could still exist from a metaphysical point of view. What the compilation of available data and hermeneutical tools do for us is allow us to assign the species to one of any number of different conservation categories, depending upon what the final analysis turns out to be.
The Conservation Categories Themselves
The IUCN RedList utilises a range of conservation categories such as 'Vulnerable', 'Endangered' and 'Critically Endangered'. Most of these categories are what we might call onto-epistemic categories. They are a hybrid between ontology and epistemology. They represent our beliefs about the ontic status of the assessed taxon. That is, they attempt to say something about us but also something about external reality (in this case, reality beyond the conjunction of all humans2). They speak to our beliefs/knowledge of the assessed taxa. Of course there is one exception. The category 'Data Deficient'. This is a purely epistemic category, one that speaks to the paucity of data, and therefore our ignorance, and therefore our inability to confidently assign the taxon to any particular category that says something about the taxon itself and the health of its global population. It is a position of agnosticism.
Conclusion
When one speaks of the conservation status of a (sub)population, (sub)species etc. one can claim knowledge of a taxon's true ontic status. Or one can simply mean that given the balance of evidence, the most likely status of the wild/captive global population is this or that category. In general what is meant is the latter. After all, the former strays as much into philosophy as it does biology. The issue of whether true knowledge (i.e. cartesian certainty) is even metaphysically possible is highly contentious. One can of course retort that such a definition of knowledge is far too strict, and that the term is more often used to mean something epistemically much less strict. But then this kind of 'knowledge' starts look awfully like the evidential position espoused by the latter approach.
Notes
1 One of the definitions of 'provincial' is a '[general] lack of culture'. The provincial reversal of entropy (i.e. the origin and evolution of life) means that that lack of culture is no longer the case. Most people would consider bacteria as primordial life, and a culture (i.e. special kind of group) of bacteria being plural instead of the singular represents the increase of life. Bacterial culture, now routine research tools in medicine (which combines both epistemology and ontology (the subject of this article), the study of the process that created us. Like the illustration of the eye sat atop the left-hand column of the 'U' shape that is able to gaze back at the process that it is the end product of. Although I wouldn't wish to affirm any speciesistic notion that we are in any way superior to any other form of life, despite mainly religious claims to the contrary). An ultra punny element for those who desire it.
2 Technically, 'humans' covers any member of the genus Homo. But since we are the only extant taxon I am using the term as a synonym of Homo (sapiens) sapiens.
Published 5 August 2017.
We'll Still Be Killing Species After We've Died Out
By Branden Holmes
We humans are guilty of catastrophically modifying the planet. And what is worse is that often it backfires. For example, leaving deforested areas barren and unproductive after a soil's nutrients have been used up by binge agriculture and erosion has set in. Unlike most other species we do not instinctively regulate our own behaviour in order to preserve resources for the future. We simply plunder and pillage, both the land and the sea, and then move to a new area, repeating both the process and our previous mistakes. We might reproduce like any other sexual species, but uniquely we have sophisticated medicine which takes a blanket approach, healing not just the healthy but also the sick and dying. Thereby defying natural selection and fueling our global growth out of all proportion to what is sustainable. Thus we have an insatiable thirst for resources which has driven us to exploit the planet to the maximal degree. And we have now affected it to such an extent that we have caused global climate change.
Beyond climate we have also destroyed much of the biodiversity that existed when our species was in its infancy. A situation that constitutes life's greatest 'geologically sudden depletion since the time of the terrible lizards (i.e. dinosaurs). We have greatly reduced the global population of species. We have hacked away at the Tree of Life, lopping off leaves, twigs and even branches; whole groups of organisms simply gone. Millions of years worth of evolutionary knowledge have disappeared down the drain of extinction. And it's all our fault. Cloning is too little, too late.
There are three key ways in which we reduce biodiversity:
1. We reduce species
The first way in which we reduce biodiversity is by driving species (and subspecies) extinct. This is the most obvious and direct way in which we adversely affect biodiversity, and with which the greater portion of this website is concerned. So I shall say very little else about it here, except to note one point in particular. The loss of subspecies is generally treated with less of a concern than full species. The only exceptions being situations where all recent subspecies of a species go extinct (e.g. Xenicus longipes, the bush wren or mātuhituhi). Or, the subspecies was from a beloved species. While this differential concern is justified to some degree (viz. greater genetic loss), it is also arbitrary in two important ways: (recent) monotypy is accidental, and subspecies are species-in-waiting.
2. We reduce genetic diversity
Natural selection acts upon 'visible' genetic differences between individuals, which by virtue of heritibility bestow differential survival capacity and fecundity upon their biological benefactors. With less genetic diversity, individuals within a population will tend to be more similar, including in their susceptibilities and weaknesses (i.e. their reproductive fate). And individuals in highly inbred populations are basically clones of each other. A disease epidemic which kills one individual is likely to kill most if not all of the others too.
Species which have fallen below the viability threshold may still reproduce, but such efforts are in vain. Their species has been earmarked for obliteration. All that is left is for them to actualise their extinction. A lack of genetic diversity clearly hinders adaptation (see below), but in high levels can affect the individual's ability to survive at all, let alone reproduce. Individuals with severe deformities, one of the common consequences of inbreeding, are almost guaranteed to die without ever having left any descendents. Except, perhaps, members of our own unique genus. Modern research is uncovering just how sophisticated Neanderthal medicine was.
Most loss of genetic diversity isn't anywhere near as immediately consequential for a population as inbreeding since inbreeding is at the extreme end the loss spectrum. With the greater part of the spectrum allowing for the population to stay above the viability threshold. But with the loss of every gene (technically, allele) the population loses adaptive potential. Certain genes may enhance the survivability of individuals, and if they are expunged from the gene pool then the species becomes more likely to go extinct. However, environmental changes will continue long into the future (including human-caused climate change), and hence the loss of genetic diversity now can affect the ability of species to adapt in the future after we've gone.
3. We reduce individuals (and erect reproductive barriers)
A smaller population can have more genetic diversity than a larger population. This is because there is only a weak to strong correlation between the number of (a)sexually reproducing individuals in a population and genetic diversity within that population. In order to make the crucial distinction between individuals and genetic diversity, consider four possible scenarios that cause a genetically diverse population to head towards extincion:
- The individuals are geographically (or otherwise reproductively) isolated from one another.
- There is a seriously skewed male:female sex ratio. At the extreme end, the population can represent only one sex.
- The individuals are well past their sexual prime.
- The individuals are sterile.
Moreover, a population can be afflicted by multiple of these worst case scenarios.
Losing the Knowledge to Survive
Life on Earth has existed for roughly four billion years. During that time it has acquired the knowledge to survive. Knowledge which is now being slowly eroded away by humans as we reduce biodiversity. Life as a whole is incredibly resilient, and may actually have originated in outerspace (panspermia), travelling to Earth only once it had evolved, seeding the planet with DNA. It flowered after the evolutionary innovation that was the eukaryotic cell, and has to date produced a wide variety of bauplans. A series of major body plans to which virtually all species can be ascribed.
Life has suffered several mass extinctions, during which time the Tree of Life was ravaged, like trees after a storm. But life has managed to survive all of these, and in fact has bounced back stronger than previously. Life has accrued the knowledge to survive even the harshest of conditions, due to genetic diversity, which can be seen as an investment in the future of the population. Almost pre-empting catastrophe.
The different genomes (that is, the sum total of the genes) of individuals render them differentially capable of surviving, which is why some individuals leave no descendents while others leave a multitude of viable offspring. In the short term this is a problem for the species as the reason many individuals don't survive and reproduce is because of mutations, many of which are not conducive to reproductive success. Mutations which could have been advantageous to survival, and if inherited would have increased survival rates and hence a population increase (if correlated to greater reproductive success).
But in the long term with a dynamic environment the goal posts change. An individual which would have been considered (relatively) unfit a few thousand generations ago may now find itself the fittest of the lot. What is beneficial is relative to the environment in which the individual has to survive. And with the environment ever-changing one cannot predict which characteristics will give individuals the greatest reproductive advantage. It is lucky that with individuals so different to each other that at least some of them will probably have the genetic makeup to survive a given environmental change, and be able to go on and found a new population.
The term 'environmental change' is a rather ambiguous one though. To take one aspect, the length of time over which the change occurs can be orders of magnitude different. A hailstorm can be considered an environmental change if it is particularly severe. And one which by virtue of it's nature can have the effect of killing individuals randomly in terms of their fitness level. A fitter individual is not necessarily at any greater advantage to be able to survive the hailstorm than other individuals. It can simply be a matter of circumstance. Which individuals get caught out in it and which were already safe or were able to get to safety.
When we reduce the size of a population's gene pool we create the situation whereby the individuals in that population are more similar to each other than previously. Their individual fate is more likely to be similar to that of other individuals. Instead of there being some individual rabbits which by pure coincidence just happened to have genomes which made them resistant to myxamatosis, if we had of reduced their numbers drastically prior to releasing the virus here in Australia in 1950, then with less genetic "options" actualized there would have been a much less chance that some of the individuals would have been able to survive the disease.
The advantages of lost genetic diversity
The loss of genetic diversity isn't all one way, however. In fact there are circumstances under which it is good for a species to lose genetic diversity. The loss of alleles (gene variants) means less competition for any advantageous mutations which may occur, facilitating their spread through the population. Although such scenarios will be extremely rare and not detract significantly from the general rule that the loss of genetic variation in a population is invariably bad. Especially since such advantages can really only be diagnosed in hindsight, after the loss of the diversity. It remains the case that humans are generally bad for biodiversity even if we do on occasion help remedy some tiny proportion of the problem we caused in the first place.
Evolution on a post-human planet
The arising of speculative evolution (or speculative biology) has led to an increased interest in what life will be like in the future, especially in the absence of the restrictive effects of humanity and its destructive habits. Unfortunately, the movement tends to place more emphasis on the artistic/imagination side of things, with biological reality taking a back seat. In actuality no species is capable of an infinite amount of change in a given direction, and certainly not in any direction whatsoever. There is a such thing as phylogenetic constraint.
'Design space', the sum total of combinations of physically possible life forms, is traversed only by the thinnest of thin webs which represent what the philosopher Daniel Dennett has called biologically possible life forms. Life forms which could not merely exist as isolated individuals (what is physically possible), but could actually survive in an environment surrounded by other life forms, competing for resources, and capable of reproduction (whether sexual or asexual).
It seems to me that the greatest consideration that speculative evolutionists need to take into account is the enduring effect that we humans will have on the rest of the planet even long after we are gone. The failure of many species to adapt to future changes to their environment will be the result of humans, caused by lost genetic diversity suffered thousands, if not millions, of years in the past (in the future). Evolution cannot be predicted, but knowing that many ecological niches will be vacated because of us, and the relatively high extinction rate (compared to the background extinction rate), the relative selective pressures upon populations will be consituted quite differently in the actual future than what would have been the case if we had never of evolved in the first place, or at least not become as evolutionarily successful as we did.
Pauline Taxa: Fossil Taxa Later Discovered Alive
By Branden Holmes
In addition to the many millions of living species which have been described, a few very special taxa have been named upon the basis of fossil or subfossil material only to later be discovered still living. Although often called Lazarus taxa in both the technical and popular literature, an allusion to the story of the Biblical Lazarus whom Jesus raised from the dead after four days (John 11:1-44), pronunciation of extinction in each of these cases turned out to be premature, unlike that of Lazarus. None of them were really resurrected from the dead like Lazarus, or the Pyrenean ibex (Capra pyrenaica pyrenaica), the only true Lazarus taxon to date (Folch et al., 2009)1.
Instead the reappearance of most taxa, both those discovered and rediscovered as living, should rather be likened to Paul in Acts (Acts 14:19-20), when he is stoned, putatively to death, but recovers, clearly never having actually been dead. And hence these taxa should be more appropriately referred to as Pauline taxa rather than Lazarus taxa, a name which I shall adopt throughout this website.
Table 1. An incomplete list of Pauline taxa.2
Scientific name | Type of animal/plant | Last record | Rediscovered | Source/s |
Adeonella adae | (bryozoan) | Late Pleistocene | 2000's? | Rosso & Novosel, 2010 |
Alytes muletensis | Toad | Late Pleistocene | 1979 | |
Aproteles bulma | Bat | |||
Aristena rechingeri |
subfossil | 2020-2021? | Grano & Cattaneo, 2021 | |
Awalycaeus yanoshokoae | Snail | |||
Bibimys labiosus | Rodent | 1980 | ||
Blarinomys breviceps | Rodent | |||
Burramys parvus | Possum (marsupial) | ? | 1966 | |
Calliostoma bullatum | marine snail | Middle Pleistocene | ||
Canariella pontelirac | Snail | |||
Catagonus wagneri | Peccary (related to pigs) | ? | 1974 | |
Coenocorypha aucklandica perseverance | Bird | |||
Crocidura religiosa | early 1900's | Woodman et al., 2017 | ||
Cuscomys oblativa | Rodent | 1500's? | 2009 or 2012 | |
Cyclocypris diebeli | Crustacean | |||
Cymatioa cooki | bivalve | Late Pleistocene | 2018-2019 | Valentich-Scott & Goddard, 2022 |
Discula cameroni | land snail | ? | 2020 or before | Cameron et al., 2021 |
Discus macclintocki | land snail | Late Pleistocene | 1955 | |
Eschrichtius robustus | Gray whale, Grey whale | ? | 1930's | Wikipedia |
Geomitra coronula | snail | subfossil | late mid-1800's | Teixeira et al., 2018 |
Hemicycla eurythyra | Snail | |||
Lundomys molitor | Rodent | Late Pleistocene | 1993 | Voss & Carleton, 1993 |
Mastacomys fuscus mordicus | Rodent | |||
Mesocapromys nanus3 | Rodent | pre-1938 | EDGE website | |
Muntiacus gigas | Deer | Holocene? | 2016? | Turvey et al., 2016 |
Natalus jamaicensis | Bat | |||
Natalus primus | Bat | |||
Nesopupa turtoni | (land snail) | subfossil | 2003 | |
Paulamys naso | Rodent | ? | 1991 | |
Phyllodactylus sp. nov. 'Rabida Island' | Gecko | c.5,000yBP | 2012 | |
Porphyrio hochstetteri | Rail (bird) | ? | 1850 or before | Mantell, 1850 |
Potorous tridactylus trisulcatus | Bettong (macropod) | ? | 2012 | Frankham et al., 2012; Jackson & Groves, 2015 |
Pseudorca crassidens | Whale | 1861 | ||
Pseudoryzomys simplex | Rodent | 1991 | ||
Rhynchotalona latens | Crustacean | Quaternary | ? | van Damme & Nevalainen, 2019 |
Speothos venaticus | Canid | ? | 1843 | |
Tonatia saurophila | Bat | |||
Vertigo pseudosubstriata |
Snail | Late Pleistocene | 1984 or prior | Schilyenko, 1984; but see Meng et al., 2021 |
Ziphius cavirostris | Whale | ? | 1872 |
Table 2. Rediscovery of ghost lineages.
Scientific name | Type of animal/plant | Rediscovered | Source/s |
[carp gudgeon] |
Table 3. Pauline taxa later shown to represent a different species.
Scientific name | Type of animal/plant | Initial claim of rediscovery | Rediscovery shown to represent another species |
Elseya lavarackorum | (turtle) | Thomson et al., 1997 | Joseph-Ouni et al., 2020 |
Table 4. Recent taxa considered extinct when described but later rediscovered
Scientific name | Type of animal/plant | Report of rediscovery |
Pupoidopsis hawaiensis | (snail) | Gargominy et al., 2020 |
Table 5. Long extinct species rediscovered via discovery of an extant subspecies
Scientific name | Type of animal/plant |
Gyldenstolpia fronto chacoensis (Gyldenstolpe, 1932) | cricetid rodent |
Appendix 1: Potential future additions to this list
- The fossil species Sarcophilus laniarius (Owen, 1838) might be conspecific with the extant Tasmanial devil, Sarcophilus harrisii (Boitard, 1841).
Appendix 2: Species first recorded as fossils and later as living individuals prior to scientific description
- Tellina cockburnensis (Kendrick & Brearley, 1984).
Appendix 3: Long extinct genera (or higher) rediscovered via description or transfer of living species
- Alavesia leukoprosopa Amorim et al., 2020
- Dromiciops gliroides Thomas, 1894 [family Microbiotheriidae thought extinct prior to rediscovery]
-
Eidothea zoexylocarya A.W.Douglas & B.Hyland (1995)
-
Eurhodia relicta Mooi, 1990
- Gracilidris pombero Wild & Cuezzo, 2006
- Laonastes aenigmamus Jenkins et al., 2005 [family Diatomyidae thought extinct prior to rediscovery]
- Order: Tryblidiida (Lemche, 1957)
- Submyotodon caliginosus
- Wollemia nobilis (W.G.Jones, K.D.Hill & J.M.Allen, 1995)
Notes
1 Although the Southern gastric brooding frog (Rheobatrachus silus) has also been resurrected, albeit in a restricted sense (see Phillips, 2013).
2 I owe a debt to a blog post by vertebrate palaeontologist Darren Naish.
3 Sadly this species is now believed to be extinct. The last known individual was collected in 1937.
References
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Cameron, Robert A. D., Teixeira, Dinarte, Pokryszko, Beata, Silva, Isamberto and Groh, Klaus. (2021). An annotated checklist of the extant and Quaternary land molluscs of the Desertas Islands, Madeiran Archipelago. Journal of Conchology 44(1): 53-70.
van Damme, Kay and Nevalainen, Liisa. (2019). The most latent cladoceran in the Holarctic revealed—sinking Unapertura Sarmaja-Korjonen, Hakojärvi & Korhola, 2000 into the genus Rhynchotalona Norman, 1903 (Branchiopoda: Cladocera: Chydoridae). Zootaxa 4613(3): 463-476.
Douglas, A. W. and Hyland, B. P. M. (1995). Subfamily Eidotheoideae (Appendix). Flora of Australia Vol. 16: 472-473 (ABRS/CSIRO Publishing: Melbourne).
Folch, J., Cocero, M. J., Chesné, P., Alabart, J. L., Domínguez, V., Cognié, Y., Roche, A., Fernández-Árias, A., Martí, J. I., Sánchez, P., Echegoyen, E., Beckers, J. F., Sánchez Bonastre, A. and Vignon, X. (2009). First birth of an animal from an extinct subspecies (Capra pyrenaica pyrenaica) by cloning. Theriogenology 71(6): 1026-1034. [Abstract]
Frankham, Greta J., Handasyde, Kathrine A. and Eldridge, Mark D. B. (2012). Novel insights into the phylogenetic relationships of the endangered marsupial genus Potorous. Molecular Phylogenetics and Evolution 64: 592-602. https://doi.org/10.1016/j.ympev.2012.05.013
Gargominy, Olivier et al. (2020). Discovery of the Only Living Population of Pupoidopsis hawaiensis (Gastropoda: Pupillidae) in the Last 50 Years. American Malacological Bulletin 38(1): 50-54. https://doi.org/10.4003/006.038.0103
Grano, Mauro and Cattaneo, Cristina. (2021). Rediscovery of Assyriella rechingeri (Fuchs et Käufel, 1936) (Gastropoda Helicidae) in Karpathos Island (Dodecanese, Greece). Biodiversity Journal 12(2): 467-474. https://doi.org/10.31396/Biodiv.Jour.2021.12.2.467.474
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Jones, W. G., Hill, K. D. and Allen, J. M. (1995). Wollemia nobilis, a new living Australian genus and species in the Araucariaceae. Telopea 6(2-3): 173-176.
Joseph-Ouni, M., McCord, W.P., Cann, J., Smales, I., Freeman, A., Sadlier, R., Couper, P., White, A. and Amey, A. (2020). The relics of Riversleigh: Re-examination of the fossil record of Elseya (Testudines: Chelidae) with description of a new extant species from the Gulf of Carpentaria drainages, Queensland, Australia. The Batagur Monographs 3: 7-69.
Kendrick, G. W. and Brearley, A. (1984). A new species of Tellina (Tellinides) (Bivalvia: Tellinidae) from Western Australia. Journal of the Malacological Society of Australia 6(3-4): 181-190.
Lemche H. (1957). A new living deep-sea mollusc of the Cambro-Devonian class Monoplacophora. Nature 179: 413-416, fig. 1-4
Mantell, G. A. (1850). Notice of the Discovery by Mr. Walter Mantell, in the Middle Island of New Zealand, of a living specimen of the Notornis, a bird of the rail family, allied to Brachypteryx, and hitherto unknown to naturalists except in a fossil state. Proc. Zool. Soc.. Lond. pt. 18. 209-212.
Meng, Stefan, Vasyliev, P., Khoptynets, I., Tkach, V. and Maier, A. (2021). On the present habitats and ecology of Vertigo pseudosubstriata Ložek, 1954 (Mollusca, Gastropoda, Vertiginidea) in Central Asia and its distribution history in Central and Eastern Europe. Journal of Quaternary Science 36(6): 1090-1100.
Mooi, Rich. (1990). A new “living fossil” echinoid (Echinodermata) and the ecology and paleobiology of caribbean cassiduloids. Bulletin of Marine Science 46(3): 688-700.
Phillips, Nicky. (2013). Extinct frog hops back into the gene pool. The Sydney Morning Herald, 16 March (Saturday).
Rosso, Antonietta and Novosel, Maja. (2010). The genus Adeonella (Bryozoa, Ascophora) in the Mediterranean, with description of two new living species and rediscovery of a fossil one. Journal of Natural History 44(27-28): 1697-1727. [Abstract]
Schileyko, A. A. (1984). Nazemnye molljuski podotryda Pupillina fauny SSSR (Gastropoda, Pulmonata, Geophila). Fauna SSSR, Molljuski 3(3): 399. [in Russian].
Teixeira, D., Silva, I., Cameron, R. and Groh, K. (2018). Geomitra coronula. The IUCN Red List of Threatened Species 2018: e.T121001523A121001604. https://dx.doi.org/10.2305/IUCN.UK.2018-1.RLTS.T121001523A121001604.en. Accessed on 22 October 2022.
Thomas, Oldfield. (1894). On Micoureus* griseus, Desm., with the Description of a new Genus and Species of Didelphyidae. The Annals and Magazine of Natural History; Zoology, Botany, and Geology (6) 14: 184-188.
Thomson, S. A., White, A. and Georges, A. (1997). Re-evaluation of Emydura lavarackorum: identification of a living fossil. Memoirs of the Queensland Museum 42(1): 327-336.
Turvey, Samuel T. et al. (2016). Holocene range collapse of giant muntjacs and pseudo-endemism in the Annamite large mammal fauna. Journal of Biogeography. DOI: 10.1111/jbi.12763 [Abstract]
Valentich-Scott, Paul and Goddard, Jeffrey H. R. (2022). A fossil species found living off southern California, with notes on the genus Cymatioa (Mollusca, Bivalvia, Galeommatoidea). ZooKeys 1128: 53-62. https://doi.org/10.3897/zookeys.1128.95139
Voss, R. S. and Carleton, M. D. (1993). A new genus for Hesperomys molitor Winge and Holochilus magnus Hershkovitz (Mammalia, Muridae) with an analysis of its phylogenetic relationships. American Museum Novitates 3085: 1-39.
Wild, Alexander L. and Cuezzo, Fabiana. (2006). Rediscovery of a fossil dolichoderine ant lineage (Hymenoptera: Formicidae: Dolichoderinae) and a description of a new genus from South America. Zootaxa 1142: 57-68. https://doi.org/10.11646/zootaxa.1142.1.5
Woodman, Neal, Koch, Claudia and Hutterer, Rainer. (2017). Rediscovery of the type series of the Sacred Shrew, Sorex religiosus I. Geoffroy Saint-Hilaire, 1826, with additional notes on mummified shrews of ancient Egypt (Mammalia: Soricidae). Zootaxa 4341(1): 1-24. [Abstract]
Rediscovery versus Relocation of "Missing" Taxa
By Branden Holmes
A list of rediscovered species and subspecies seems at first easy to compile, apart from the obvious difficulty of getting hold of all of the relevant literature. However, the distinction between extinction and a lack of sightings quickly blurs once one starts to research. Just because a taxon has not been seen in many years does not necessarily mean that it is likely to have become extinct. Many species live in remote areas away from human habitation, and as scientists rarely travel to these localities records of these plants and animals will obviously be similarly rare. Whereas for a species which either mainly or wholly inhabits an area which corresponds with a high human population a complete lack of sightings should be regarded as far more reflective of the actual conservation status of that species. Most species occupy a natural range somewhere intermediate between these two extremes of socio-geography, and hence the probability of their persistence or extinction after x number of years without a definite sighting is difficult to quantify, making it difficult to set conservation targets and priorities. In this particular case, deciding which "missing" taxa to search for.
Conservation Biology
Conservation biology has two main goals: to preserve biodiversity, and to preserve genetic diversity. Normally these go hand in hand, however there are sometimes difficult decisions which require biologists to concentrate on one to the detriment of the other. It is not always possible to conserve a viable population of genetically healthy individuals. Sometimes we need to conserve the species without as much regard to genetic diversity as is preferable under ideal circumstances, and can then go about making sure it persists long enough into the future that genetic mutations build up again to pre-bottleneck levels to restore genetic diversity (which often produces a very different genome, with polymorphisms at different chromosomal loci). But before biologists can go about conserving a species they first need to confirm that it still survives.
Many people would be surprised to learn that a great percentage of described species are known only from the type specimen or type series, in some cases collected more than 100 years ago. This is especially so for invertebrates. Scientists are constantly battling for funding, and that includes those who are not in the field of the life sciences. It would be nice to confirm the persistence of all of these taxa, however limited resources often puts a stop to any such hope. If a species does not face any obvious threats to its survival then any expedition just to confirm its persistence would be viewed as a waste of money. But there are other species whose continued existence is much less certain, and does potentially qualify for funding. But there are simply too many "missing" species in need of relocation/rediscovery to go and look for them all. Conservationists need to prioritise.
It is therefore of significant use to conservationists (and others) if we can create criteria which can be used to quantify what might be termed the likelihood of persistence (hereafter LP) of a taxon, which, if they are found again, would qualify as either rediscovered or relocated, depending upon whether their LP was <50% or not. With limited funds, conservations want the greatest "bang for their buck" so to speak, and hence it is necessary to weigh up the two factors of likelihood of persistence versus likelihood of extinction, which are really expressed in the same fraction (a 40% chance of survival means a 60% chance of extinction, and vice versa). Populations which have not been recorded in decades, but which face no obvious threats to their survival, justifiably deserve less conservation attention than a species which has been recorded many times before but whose population has dwindled in recent years to the point where it has not been recently seen, especially if species-specific searches have been conducted.
But expeditions/surveys often fail to find target species for any number of reasons, including: incorrect survey methods, insufficient area covered, insufficient planning, external factors such as the weather, etc. They are not fool proof, and usually several expeditions/surveys are needed to identify potentially extinct taxa, as each generally covers a different geographical area unless a taxon happens to be historically only known from a small area, perhaps the type locality only. But as rediscoveries as of recent show, we cannot write off species just because they have disappeared from their type locality, even if that is the only locality from which they are definitely known (ie. to which historical records were confined), because although the species may not have been recorded from other suitable habitat it is not always easy to distinguish phantom taxa (i.e. existing unseen in a given area) from ecological rarity (i.e. naturally rare).
Ethnoknowledge
But what about sightings of putatively missing or extinct species by natives? What if they continue to report it's existence although Western scientists never sight it, and it is subsequently found to still persist? Could that count as having been “rediscovered”? Simplistically, the only reasonable answer would be "no" as there is no good reason to view ethnoknowledge of a species as either inferior when compared with Western knowledge of plants and animals, or worthless, which is tantamount to racism. However, one needs to know whether those same native people could have some ulterior motive for "sighting" a plant or animal regularly. And hence it is important to weight their sightings according to their trustworthiness, which should be quantified as objectively as possible.
Native people are often an excellent source of knowledge about the flora and fauna which occur in a particular area, as well as which ones to avoid (e.g. which plants are edible and which are not), and which are harmless or, even better, of some economic use. It is not too much of a stretch to say that their lives depend upon it, especially when any potential help is days away if they are stung or bitten or attacked. But at the same time they may not be so non-chalant about sharing their knowledge, especially if that could potentially mean competition for a limited resource. So it is important to be aware of any possible deliberate misinformation being fed to the conservationist.
Relocation
Until the early 20th century the collecting of museum specimens for collections went largely unabated. Any unusual specimen was simply shot, trapped, traded, or otherwise obtained in the hopes that it would prove to be a new species. It is not surprising then that museums are stuffed with unusual specimens; aberants and mutants whose true affinities may deceive. And until the discovery of the chemical structure of DNA (deoxy-ribo-nucleic acid), which allows scientists to delve into the genome of an individual and sequence its genes, they couldn't tell whether one of these specimens was simply an abnormal specimen or a new species. Pre-DNA taxonomists classified species predominantly using the morphological species concept (MSC), or using alpha taxonomy, so that abnormal specimens could not definitely be separated from new species because they both differed phenotypically from all previously described forms. It was only the degree of divergence from described forms which separated mutants from subspecies, and any talk of degree is necessarily subjective.
There are therefore many specimens in museums which were assumed to be just such abnormal specimens which did not prove to be morphologically distinct enough to warrant description as a new taxon, but which using modern DNA analysis we now realize actually are "good" species. But given the close physical resemblances of many species within a genus it is easy to see how such confusion arose in the first place. Thus these abnormal specimens, actually new species, simply sat in museums around the world until serendipity intervened and they were recognized for what they really are. Unfortunately, most of the species which have been supposedly rediscovered have been of this nature: specimens held in museums for years, even decades, until it is realized that they are actually new species. Then scientists go on an expedition and "rediscover" it. Species which daily encountered humans, and which were forced into extinction as a result, are invariably never rediscovered. One could therefore say that only a handful of genuine rediscoveries have actually been made, while the rest were never really feared extinct in the first place. It’s just that nobody bothered to look for them, or because nobody knew to (perhaps because of incorrect locality data):
"The status of many tropical species is unknown, because no one has seen them again or specifically looked for them since they were discovered. For instance, among the New Guinea birds that I study, Brass's friarbird is known only from eighteen specimens shot at one lagoon on the Idenburg River between 22 March and 29 April 1939. No scientist has revisited that lagoon, so we know nothing about the current status of Brass's friarbird."1
(Jared Diamond, The Rise and Fall of the Third Chimpanzee, p. 316)
The fact that a species has not been seen in many years is, when considered in isolation from other potential factors, an insufficient indicator of the conservation status of a population. More than 50 years had passed since Brass's friarbird was last seen when Diamond wrote The Third Chimpanzee. And yet nobody even considered the possibility that it could have become extinct in the mean time since it presumably faced no long-term threats above and beyond those of everyday life. Thus, when Brass' friarbird was found again it was a case of relocation and not rediscovery.
Rediscovery
But what then is a good indicator of extinction? And hence, what is a good indicator of genuine rediscovery, as opposed to relocation? Of course, if we only declare those species officially extinct for which we have surveyed their entire habitat, or whose habitat has been completely destroyed, then no species will ever be rediscovered. It seems ironic then that for the term "rediscovery" to retain any purpose in the language of conservation biology our criteria for declaring a species extinct cannot be too stringent.
I propose an arbitrary cut-off point to demarcate "rediscovery" from "relocation". This separates species found to still persist after an extended period of time (which is subjective) into two categories:
A. 0-49% chance of the taxon having become extinct. Such taxa should be referred to as having been "relocated" as there was never really any great question over their continued existence, especially for the lower percentages. Though for those percentages approaching 50% there may have been some doubt as to their persistence.
B. 50-100% chance of the taxon having become extinct. Such taxa should be referred to as having been "rediscovered" as there was, at minimum, an equal chance that it had become extinct as that it still persisted, through to a very good chance that they had become extinct during the intervening period during which no confirmed sightings were made.
Clearly 0% and 100% are "impossible categories", contradictions in conservation. No population can be relocated if there was a 0% chance of its extinction since the last record, since the only way in which we could say that there was such a low probability of extinction in the first place (i.e. no chance) was if we had certain knowledge of its persistence into the present. And for 100%, as I pointed out earlier, a species which is definitely extinct (both in the wild and in captivity2) cannot therefore be rediscovered. It can only be brought back through "de-extinction", as it has come to be known.
Conclusion
Unfortunately neither the Dodo nor the Yangtze River dolphin nor the Thylacine, nor numerous other iconic extinct species are ever likely to return to us. They are sadly almost certainly gone forever, as it now seems that cloning the Thylacine is impossible from the fragmented state of DNA in all suitably preserved specimens. A constant reminder of the ignorance we once possessed and are still finding hard to shrug off. Unfortunately it is only when things are gone that you realize how special what you had was. If only that wasn’t true, we wouldn’t be heading towards an ecological disaster of global and bio-historic proportions.
But alas it is true, and it couldn’t really be any other way. Thus, we find ourselves trying to make so much out of so little; trying to reunite all of the various Thylacine artefacts held in museums around the world, hoping that something will change. Even though such an effort is so detached from the possibility of its continued survival that not only do we know it subconsciously, but also consciously. Nevertheless, our guilt drives us to do such things as a part of the grieving process...
Notes:
1 In case you were wondering, Brass's friarbird has now been found at other locations since Diamond's book was published (1991), though it's population size is still unknown and only a very few records attest to it's existence.
2 It has been suggested in recent years that there are pure bred Barbary lions (Panthera leo leo), originally from North Africa, in zoo collections. However, these claims are doubtful as genetic analysis of putative Barbary lions has failed to substantiate these claims so far.
References:
Diamond, Jared. (1991). The Rise and Fall of the Third Chimpanzee: How Our Animal Heritage Affects the Way We Live (2002 Vintage pb. edition). London: Vintage.
BirdLife International. (2011). Species factsheet: Philemon brassi. Downloaded from http://www.birdlife.org on 17/01/2011.
Published on 20 April 2014
Modern Sightings of Putatively Extinct Taxa
By Branden Holmes
Despite being officially listed as extinct (e.g. IUCN, 2015) there are some species (and subspecies) of animals which are still being 'seen'. There have even been several (extremely dubious) sightings of the Dodo (Raphus cucullatus) since the 1970's, or more than 300 years after the last incontrovertible record of the species which was in c.1638 (Fuller, 2002). Taxonomic and iconographic bias is evident in these sightings as the vast majority of reports concern either mammals or birds1, especially famous ones. This bias is not unexpected for several reasons:
- Putatively extinct mammals and birds are better known to the general public than animals from other taxonomic groups.
- Birds and mammals are some of the most readily enountered animals (especially birds).
- Plants and invertebrates are of much less interest to most people.
Only a very few putatively extinct invertebrates could by any stretch of the imagination be called well-known, such as Buller's moth (Aoraia mairi) and the previously thought to be extinct Lord Howe Island phasmid (Dryococelus australis). And even then their fame does not approach anywhere near that of their tetrapod cousins. And equally few non-mammalian non-avian vertebrate species which are believed to be extinct are widely known. Most of the iconic putatively extinct species and subspecies are mammals or birds. Some examples are:
- The thylacine or Tasmanian tiger (Thylacinus cynocephalus), last seen 7 September 1936.
- Steller's sea cow (Hydrodamalis gigas), last seen in 1768.
- Ivory-billed woodpecker (Campephilus principalis principalis), last seen in 1944.
- Baiji, or Yangtze River dolphin (Lipotes vexillifer), last seen in 2002.
- Paradise parrot (Psephotus pulcherrimus), last seen in 1928.
- The Dodo (Raphus cucullatus), last seen c.1638.
- Passenger pigeon (Ectopistes migratorius), last seen 1 September 1914.
Interestingly, there have been numerous post-extinction (putatively) reports of all of these species, especially of the Thylacine (5,000+). And the so-called 'rediscovery' of the Ivory-billed woodpecker has been widely covered in the scientific literature (Wilcove, 2005), though the video footage taken almost certainly depicts a Pileated woodpecker (Dryocopus pileatus) (Collinson, 2007, and others). Though caution must be heeded as the famousness of these species in itself is probably the cause of some extra number of sightings than would otherwise have been the case if they were species which were otherwise unremarkable. In regards to other members of the groups birds and mammals, and other taxonomic groups (fish, reptiles, amphibians etc.), the observer may simply put down a sighting of an animal unknown to them as simply a species which they are not familiar with. It may not even occur to them that the animal they observed belonged to a species presumed to be extinct.
The three categories
Reported sightings of putatively extinct taxa fall into one of three categories:
- Hoaxes or deceptions.
- Misidentifications.
- Genuine sightings.
In my personal experience those people who report the occurrence of events, or the existence of animals, which are not widely accepted are genuine in doing so. That is, they are not consciously lying. They genuinely believe that they have seen what they claim to have seen, whatever that turns out to be. And this applies equally well to previously known animals, cryptids and miracles. The greater part of the problem then is to determine whether a potential sighting belongs in category 2 or 3; whether the observer was mistaken, or whether they really did see an 'extinct' species. And having criteria to help us determine into which category a potential sighting fits, and hence in deciding whether a follow-up of the report should be made, is essential.
As my only concern here is animals which are known to have existed in the recent past (though now widely believed to be extinct) the 9 criteria I shall outline here are substantially different to the criteria which would be used by, say, a cryptozoologist or a theist investigating reports of an angelic creature. Although there would obviously be severe overlap.
The Criteria
- The report is consistent with what is known of the animal. This includes, if applicable, size, shape, movements, colour, markings, time of sighting, season, sex of the animal/s etc.
- The observer's familiarity with the species. Whether the observer has seen the species previously and knows what it looks like, preferably while alive.
- The conditions under which the sighting was made. The time of day (i.e. amount of light), the distance between the observer and the animal, the weather conditions, and the physical condition of the observer (including whether they had taken any hallucionogenic drugs in the lead up to the sighting).
- Power of observation. Whether the observer is trained in a manner which would lead us to lend more weight to the credibility of their sighting. And whether the observer was aided by any optical instruments such as binoculars, a telescope, night-vision goggles etc.
- Evidence of the animal. Whether indirect sign/s of the animal/s were seen, either just prior to the sighting or on a previous occasion.
- Evidence of the sighting. Whether photographs, video footgae or audio recordings were made which may aid with identification of the animal/s.
- The possibility of misidentification. Are there any animals (or inanimate objects) which the observer/s could have mistaken for the putatively extinct species?
- The observer's vocabulary. Whether the observer has a sufficient vocabulary in order to convey the details of the sighting as accurately as possible.
- Guilt. Whether the observer has a subconscious yearning for the species to still be alive to relieve the burden of guilt over their/our part in the extinction of the species in the first place.
These criteria should be consulted not just by those investigating reports of putatively extinct species, but the people actually making the reports as well. This would help to eliminate many cases of mistaken identity which would allow resources to be concentrated upon a core group of the sightings which have the most promise. A little elaboration on each of these criteria is therefore called for:
The report is consistent with what is known of the animal
If the observer attributes atypical behaviour to the animal then, depending upon how well known it is, that may completely discount the possibility of them really having seen the animal. Or it may merely make it more unlikely than not. But for species whose habits are wholly unknown no behaviour can be considered as atypical and hence this particular criterion does not apply in such cases. But caution must also be eased because if a species approaches extinction then inbreeding can result in all sorts of atypical or uncharacteristic behaviours which would otherwise lead to the report being dismissed out of hand.
The observer's familiarity with the species
If the observer has seen the species before, prior to its putative extinction, and preferably while alive, then misidentification is much more improbable relative to a situation where the observer only has a verbal description of the species to go by. Familiarity with a species does not in itself guarantee that any sighting must be genuine, and I have more to say about this below under the heading 'Pre-extinction sightings'. But if the observer is not only familiar with the species in question but also with any other species with which it could potentially be mistaken then their report has a lot of credibility.
The conditions under which the sighting was made
Conditions can dramatically affect the observational ability of an individual, especially if they are dehydrated, stressed, or starving. Weary desert wanders are apt to experience mirages after walking too many kilometres without sufficient water. The light factor can also affect the ability to perceive objects, especially at a distance, since they may appear indistinct or blurry, and hence increase the probability of misidentification or an ambiguous identification (i.e. a member of a genus, rather than a specific species).
Power of observation
If the observer is trained to visually intercept objects of varying distances, sizes, speeds etc. and can accurately report back on the nature of the object/s observed then we may add some weight to their report (if we have discounted intentional deceit). And if the observer is untrained in this manner then the accuracy of their report should not be considered as 100%.
Evidence of the animal
Animals often leave signs of their presence, which, being static, are more often encountered than the actual animal itself. When hunting man-eating tigers and leopards, as recounted in his books, Jim Corbett would use his jungle surroundings to his advantage, and to the disadvantage of his man-eating adversary. Although things such as hairs, footprints and scats can be misidentified, the ability to observe them for long periods, and to study them for some time, allows the observer to be more sure of the identification of the animal upon whose trail they are. And of course, if properly collected or preversed in-situ, can allow for a suitable expert to analyse the find.
Evidence of the sighting
In most instances the only evidence that a sighting actually took place is the testimony of the observer/s themselves, which can, as I have already pointed out, be quite innaccurate. Any photograph, for example, to accompany the report, especially if clear and unambiguous, can clarify the identification of the subject in the photo independently of the verbal description furnished by the observer/s, especially if identified by a recognized authority on the matter. And this can be important because there are actually two potential areas of weakness in an observer's report. The first is of course the potential for misidentification.
The possibility of misidentification
Whenever somebody reports having seen a recently extinct species, and a hoax is ruled out, the natural question to ask is "could they have been mistaken"? Many times the animal is glimpsed only momentarily which allows for a great deal of uncertainty, especially if the animal is similar in appearance to any extant species, and especially if they overlap geographically. But even if they do not overlap geographically, vagrant individuals, or individuals which escaped captivity, are both much more likely explanations than that the observer really did see an 'extinct' species.
The observer's vocabulary
The second area of potential weakness is the observer's vocabulary, or their ability to adequately represent/describe to others what they saw. This criterion may seem rather trivial but it is actually quite important in a lot of sightings. There are two links in the chain of reporting a sighting. The first of these goes from the actual source stimuli which caused the observer to have the sighting, normally an animal. And the second is either the verbal communication, or the written description, given to a third party. Both of these links create the possibility of misreporting, and hence both deserve serious attention.
Guilt
Although unlikely, it is conceivable that an observer will be subconsciously driven by guilt to see what they want to see. Namely, an individual of a species widely believed to be extinct so that they can satisfy themselves that it does indeed still exist. This may be because they feel guilty, either as an individual or on behalf of humanity as a whole, for the species' demise. Or it may be for another reason. Self-deception in humans is well known (Trivers, 2000), and therefore cannot be doubted. Any doubt over guilt causing a 'sighting' must be directed towards whether guilt is a sufficient criterion. And that will have to await further study.
Pre-extinction sightings
If sightings of a species (or subspecies) now known, or highly suspected to be, extinct are made prior to its putative extinction and within its generally accepted geographical limits then there is a tendency to take such reports at face value since many of the factors which count against observers making observations after the last unambiguous record of a taxon (as discussed above) do not count against such observers. However, the automatic acceptance of reports of a species known to have still existed at the time must be brought into question as such observers, as subjective beings, cannot by definition be infallible. And although some of the criteria listed above don't apply, others do. So that the possibility of misidentification is still too unreasonably high to simply accept at face value any pre-extinction report.
Tangible evidence
In rare cases, someone had a camera ready in anticipation. Or stumbled upon a clear trackway. Such tangible evidence dramatically increases the odds that the sighting will be either corroborated or dismissed, as agnosticism approaches untenability. Of course, evidence needs interpretation, it doesn't literally speak for itself (unless perhaps we had video of bigfoot, sasquatch, yeti etc., but those are not feared extinct). And those best able to squeeze as much information out of a print cast (or photo etc.) are qualified experts, who are invariably scientists. And a proper scientist is driven by discovery and the chance to overthrow the establishment, even without the incentive to achieve Nobel laureatehood.
Thus scientists are in the main excited by the possibility of contributing to verifying the continued existence of a putatively extinct species. Of course, it would be naïve in the extreme to think that every single scientist is a model citizen. As humans, scientists experience the gamut of human emotions and thoughts, motivations and agendas. There are unfortunately ample cases of scientists abusing their powers and privileges (e.g. Sabbagh, 1999). So that it is not merely a case of submitting evidence to an authority and receiving the report. There is an element of discernment as to which authority the evidence is sent to, or even whether one parts with the evidence in the first place.
There are sufficient cases of cryptozoologists sending off specimens, and either never hearing back or having evidence that the package never arrived at its intended destination3. And while claimed evidence of the yeti or Loch Ness monster is not directly relevant to the present article, nevertheless the protocol is largely the same: submission to experts. Thankfully such instances are very rare, and there is normally no such problems. Nevertheless, if one has had such issues in the past then one will tend to be sceptical of sending off specimens again. In such cases, it is best to conserve the evidence as best as possible until such time as one is confident enough that a reputable third-party is in a position to analyse the evidence.
That is not to suggest that non-scientists (i.e. interested amateurs) cannot competently analyse evidence. They certainly can. After all it is the knowledge itself and not a piece of paper which makes one truly qualified to analyse evidence. And scientists themselves clearly weren't born knowing what they do. They had to learn it too, by reading the same books and articles/papers that we all (hopefully) have access to. Nevertheless, science itself demands that certain protocols be met, which includes specific methodologies being followed, for example, to rule out contamination. Science's standards might be high, but they need to be. If we base our lives on science, then we better hope that the science actually stands up to scrutiny.
Conclusion
Just because a species has been officially declared extinct does not mean that it must therefore be extinct with no possibility of its survival whatsoever. There are probably lots of putatively extinct species which still survive, since it is quite clear from past cases of rediscovery that declarations of extinction are often premature, and in the case of the South Florida rainbow snake (Farancia erytrogramma seminola), purely armchair2. The problem is with the definition of 'extinction', and how stringent it needs to be. We cannot rule out a possible sighting of a putatively extinct species a priori unless there is literally no habitat left, and no chance of its existence in captivity. Barring those unlikely circumstances, each report needs to be considered (partially) on its own merits. We cannot afford to fall for the Romeo Error (Collar, 1998), and we cannot afford to let our biases dictate the outcome of any investigation into reports of 'recently extinct' species. Our personal opinion over whether the Thylacine still survives cannot influence our judgement of the soundness of any given report.
Notes:
1 Assuming that no significant bias in which sightings are reported exists. Otherwise, if sightings of species belonging to other taxonomic groups go largely unreported then the bias towards birds and mammals would be artificial.
3 There is also the fact that expert 'analysis' can be knowingly false. Australian Cryptozoologist Mike Williams
References:
Collar, N. J. (1998). Extinction by assumption; or, the Romeo error on Cebu. Oryx 32: 239-244.
Collinson, J. Martin. (2007). Video analysis of the escape flight of Pileated Woodpecker Dryocopus pileatus: does the Ivory-billed Woodpecker Campephilus principalis persist in continental North America? BMC Biology 5: 8.
Fuller, Errol. (2002). Dodo: From extinction to icon. London (UK): Collins. 192 pp.
IUCN. (2015). IUCN Red List of Threatened Species. Version 2015.1. <www.iucnredlist.org>. Downloaded on 15 February 2015.
Sabbagh, Karl. (1999). A Rum Affair: True Story of Botanical Fraud. London: Penguin. ix + 223 pp.
Trivers, Robert L. (2000). The elements of a scientific theory of self-deception. Annals of the New York Academy of Sciences 907: 114-131.
Wilcove, D. S. (2005). Rediscovery of the ivory-billed woodpecker. Science 308: 1422-1423.
Published on 21 September 2013. Updated 15 February 2015.