Reclassification of species listed as CR, CR (PE), EW and EX following Butchart et al. (2018)

A set of papers published in 2017 (Akcakaya et al. 2017, Keith et al. 2017, Thompson et al. 2017) laid out methods for quantitatively estimating a species’s probability of extinction based on parameters associated with threats, in addition to records and surveys. This method has since been tested on 61 confirmed or potentially extinct bird species by Butchart et al. (2018).

In Butchart et al. (2018) a series of six different approaches were implemented, with a range of thresholds, to test the ability of these approaches to assign IUCN Red List categories to each species; and were compared to the current Red List status of these species. The recommendation from this was that to be listed as Extinct* a species would need a probability of being extant based on threats and a probability of being extant based on records and surveys of <0.1. If at least one of these probabilities were >0.5 then a species would warrant listing as Critically Endangered. For cases where at least one of these probabilities was >0.1 and both were <0.5 then a species would be recommended as Critically Endangered (Possibly Extinct)* – the species is likely to be extinct but there is a small chance it may be extant.

The recommended approach achieved an 80% match with current IUCN Red List classifications (Butchart et al. 2018), with the majority of those that didn’t match being species whose status and potential reclassification was pending the outcome of this analysis. These recommended reclassifications are presented below, with a very brief summary of recent records/survey effort as outlined in Butchart et al. (2018).

* For cases where a species still is known to exist in captivity then ‘Extinct’ can read as ‘Extinct in the Wild’.

Spix’s Macaw (Cyanopsitta spixii)

Capture for trade and continued habitat loss have led to declines in this species. The final individual known in the wild persisted until the end of 2000, but individuals are still in captivity. An individual was seen in the wild in 2016, but this is now thought to have been a release from captivity. There have been no other records since 2000, despite fieldworker presence and surveying effort.

The probability it is extant based on records and surveys is 0.00006, and the probability it is extant based on threats is 0.083. Therefore, based on the analysis of Butchart et al. (2018), it is recommended that the species be uplisted from Critically Endangered (Possibly Extinct in the Wild) to Extinct in the Wild.

Cryptic Treehunter (Cichlocolaptes mazarbarnetti)

This species’s decline is suspected to have been driven by habitat loss and degradation, and disturbance. It is only known from two localities in Brazil – Frei Caneca in Pernambuco, where it was last seen in 2005, and Murici in Alagoas, where it was last seen in 2007.

The probability it is extant based on records and surveys is 0.018, and the probability it is extant based on threats is 0.083. Therefore, based on the analysis of Butchart et al. (2018), it is recommended that the species be uplisted from Critically Endangered (Possibly Extinct) to Extinct.

Alagoas Foliage-gleaner (Phylidor novaesi)

As for Cryptic Treehunter, this species is thought to have declined due to habitat loss and degradation, and disturbance within its historical range. It also is only known from Frei Caneca in Pernambuco and Murici in Alagoas, Brazil, from where it was last recorded in 2011 and 2007 respectively. This is despite intensive search activity at these localities.

The probability it is extant based on records and surveys is 0.074, and the probability it is extant based on threats is 0.059. Therefore, based on the analysis of Butchart et al. (2018), it is recommended that the species be uplisted from Critically Endangered to Extinct.

Poo-uli (Melamprosops phaeosoma)

Endemic to the island of Maui, Hawaii, this species was first discovered in 1973. However, it declined rapidly between 1975 and 1985, predominantly due to invasive species and disease. By mid-1997 only three individuals remained. One was captured in 2004, but it died later that year. The other two individuals have not been reported since 2003 and 2004, with no others reported despite intensive surveys.

The probability it is extant based on records and surveys is 0.073, and the probability it is extant based on threats is 0.060. Therefore, based on the analysis of Butchart et al. (2018), it is recommended that the species be uplisted from Critically Endangered (Possibly Extinct) to Extinct.

Javan Lapwing (Vanellus macropterus)

This species is thought to have suffered as a result of disturbance and the conversion of its habitat for agriculture and aquaculture, while hunting may have also contributed to declines. It is only definitely known from Java, Indonesia, but there have been unsubstantiated reports from Sumatra and Timor. Surveys since 1949 have failed to locate the species, and the fact that it is supposedly impossible to miss suggests that it was not present at the sites surveyed. There have been several unconfirmed reports though.

The probability it is extant based on records and surveys is 0.465, and the probability it is extant based on threats is 0.418. Therefore, based on the analysis of Butchart et al. (2018), it is recommended that the species be moved from Critically Endangered to Critically Endangered (Possibly Extinct).

Pernambuco Pygmy-owl (Glaucidium mooreorum)

There has been extensive habitat loss within this species’s range, which has likely precipitated population declines. Despite extensive searches in Alagoas and Pernambuco, there have been only very limited records of this species: two individuals collected from Reserva Biológica de Saltinho in 1980; one recording from the same location in 1990; and a single record from Usina Trapiche in 2001.

The probability it is extant based on records and surveys is 0.317, and the probability it is extant based on threats is 0.118. Therefore, based on the analysis of Butchart et al. (2018), it is recommended that the species be moved from Critically Endangered to Critically Endangered (Possibly Extinct).

Glaucous Macaw (Anodorhynchus glaucus)

Habitat loss and capture for the cagebird trade have likely been the major causes of declines in this species. It was formerly widespread (yet local) in Paraguay, northern Argentina, southern Brazil and Uruguay. It had become rare by the early second half of the 19th century, and there have been only a few reports from the 20th century onwards. The last likely observations of the species were from Mbaracayu, Paraguay, in the late 1990s and 2001.

The probability it is extant based on records and surveys is 0.425, and the probability it is extant based on threats is 0.127. Therefore, based on the analysis of Butchart et al. (2018), it is recommended that the species be moved from Critically Endangered to Critically Endangered (Possibly Extinct).

New Caledonian Lorikeet (Charmosyna diadema)

This species is endemic to New Caledonia, and despite searches and interviews, there have been no records since 1976. Declines in the species have likely been caused by habitat loss, introduced disease and introduced mammals (e.g. rats).

The probability it is extant based on records and surveys is 0.269, and the probability it is extant based on threats is 0.262. Therefore, based on the analysis of Butchart et al. (2018), it is recommended that the species be moved from Critically Endangered to Critically Endangered (Possibly Extinct).

Moorea Reed-warbler (Acrocephalus longirostris)

Endemic to the island of Moorea, French Polynesia, the species is threatened by habitat loss, and introduced species (e.g. cats, rats, Common Myna and the neotropical weed Miconia). The last confirmed record of the species was in 1981, but there have been unconfirmed reports from the mid-1990s, 2000s and in 2010. There have been searches for the species in 1986-1987, and also some untargeted survey work in 2008.

The probability it is extant based on records and surveys is 0.894, and the probability it is extant based on threats is 0.218. Therefore, based on the analysis of Butchart et al. (2018), it is recommended that the species be moved from Critically Endangered (Possibly Extinct) to Critically Endangered.

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Additionally, there were three species that appeared to warrant a reclassification on the Red List, but instead the recommendation of Butchart et al. (2018) was to retain the current listings. These are outlined below.

Eskimo Curlew (Numenius borealis)

The probability that this species is extant based on records and surveys is 0.858, and the probability it is extant based on threats is 0.500. Therefore, the probability scores suggest that it should be listed as Critically Endangered. However, Butchart et al. (2018) recommend retaining it as Critically Endangered (Possibly Extinct) because the many claimed records since the last confirmed one (1963) all have a very low probability of being valid.

South Island Kokako (Callaeas cinereus)

The probability that this species is extant based on records and surveys is 0.898, and the probability it is extant based on threats is 0.220. Therefore, the probability scores suggest that it should be listed as Critically Endangered. However, Butchart et al. (2018) recommend retaining it as Critically Endangered (Possibly Extinct) because a recent claim is controversial, due to a lack of multiple observers and a lack of any physical evidence, and so should not be regarded as confirmed.

Olomao (Myadestes lanaiensis)

The probability that this species is extant based on records and surveys is 0.612, and the probability it is extant based on threats is 0.204. Therefore, the probability scores suggest that it should be listed as Critically Endangered. However, Butchart et al. (2018) recommend retaining it as Critically Endangered (Possibly Extinct) because the final site for the species (the Olokui natural area reserve) is only 6.6km2, less than half of which is suitable habitat, and it has been isolated for so long that it is highly unlikely that any population has persisted. The last confirmed record was in 1980, although there have been several unconfirmed records, the latest of which was in 2005.

It is proposed that these recommended status changes are taken up in the 2019 Red List update, but the topic is left open for any potential relevant comments. Please note, though, that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’s Red List status.

References

Ackakaya, H. R.; Keith, D. A.; Burgman, M.; Butchart, S. H. M.; Hoffmann, M.; Regan, H. M.; Harrison, I.; Boakes, E. 2017. Inferring extions III: a cost-benefit framework for listing extinct species. Biol. Conserv. 214: 336-342.

Butchart, S. H. M.; Lowe, S.; Martin, R. W.; Symes, A.; Westrip, J. R. S.; Wheatley, H. 2018. Which birds have gone extinct? A novel quantitative classification approach. Biological Conservation 227: 9-18.

Keith, D. A.; Butchart S. H. M.; Regan, H. M.; Collen, B.; Harrison, I.; Solow, A. R.; Burgman, M. A. 2017. Inferring extinctions I: a structure method using information on threats. Biol. Conserv. 214: 320-327. Thompson, C. J.; Koshkina, V.; Burgman, M. A.; Butchart, S. H. M.; Stone, L. 2017. Inferring extinctions II: an iterative model based on records and surveys. Biol. Conserv. 214: 328-335.

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