Unidentified rail from Tonga ? (1 Viewer)

Turdus23 said:

missing tail, very damaged wings, plucked neck, absent rhamphotecus ...

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Looking at the photo, I did not realize that the rhamphotheca is missing... I give up identification.

Turdus23 said:

All these elements lead me to believe that the only solution to be able (perhaps) to answer the question of the identity of this specimen is the DNA study: extract the DNA from the specimen and compare it to that of others species / subspecies of the genus Gallinula

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Amen to the DNA study.

Note, that no access to samples of all possible species is not a problem. Many forms can be excluded visually. If the specimen fits exactly into the DNA of some Gallinula species, for example G. tenebrosa, the answer will be simple - a mislabelled specimen or a vagrant. Only if the (exciting possibility) DNA fits into nothing available, this may motivate other museums to donate samples of their precious rare specimens.

I agree that to find out if this specimen belongs to an extant species a DNA sample would be great, but if it is an extinct species, we have no references, no DNA sample will help. Oceanic Rallidae are a problem, there are so many, most of them not described and only sometimes only known from subfossil material. DNA sampling from that subfossil material will be very problematic, and there must be many undescribed fossil Rallidae with which a comparison is not possible.

To read more about it see David William Steadman, 1995
Prehistoric Extinctions of Pacific Island Birds: Biodiversity Meets Zooarchaeology
Science 267: 1123-1131

Fred

Technically, it should be possible to x-ray the specimen from various angles and determine shape of skull, neck and leg bones still embedded in the skin? Or I am mistaken? This could eventually help to equate the specimen with some extinct species for which no DNA is available.

Note however, that as I said, DNA samples of all known rail species are not needed for identification.

agree it should be technically possible.

Niels

Fred Ruhe said:

Prehistoric Extinctions of Pacific Island Birds: Biodiversity Meets Zooarchaeology
Science 267: 1123-1131

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This paper in table 5 mentions extinct Gallinula sp. nov. from Tonga. The plot thickens. What happened to this one?

Note, that there could be an extinct species of moorhen Gallinula sp. or another unknown rail on Tonga. There are also very many recently extinct bird species in Pacific Islands. However, there are three caveats. First, species descriptions from bones can be spurious. There are at least two cases where species were described as recently extinct species on Pacific and then turned to be populations of living species (Phalacrocorax and Papasula). Then,
rules of conservation biology tell that bird populations on small islands are prone to be quickly extinct from stochastic reasons, so most species on most small islands were widespread species and gone extinct before the time required to evolve into a distinct endemics. The 1990s estimate suggesting 2000 extinct species of birds in Oceania was overestimate not understanding that factors promoting extinction (big and flightless) are correlated with promoting preservation of bones.

jurek said:

This paper in table 5 mentions extinct Gallinula sp. nov. from Tonga. The plot thickens. What happened to this one?

Note, that there could be an extinct species of moorhen Gallinula sp. or another unknown rail on Tonga. There are also very many recently extinct bird species in Pacific Islands. However, there are three caveats. First, species descriptions from bones can be spurious. There are at least two cases where species were described as recently extinct species on Pacific and then turned to be populations of living species (Phalacrocorax and Papasula). Then,
rules of conservation biology tell that bird populations on small islands are prone to be quickly extinct from stochastic reasons, so most species on most small islands were widespread species and gone extinct before the time required to evolve into a distinct endemics. The 1990s estimate suggesting 2000 extinct species of birds in Oceania was overestimate not understanding that factors promoting extinction (big and flightless) are correlated with promoting preservation of bones.

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Yes, you are right, but some remarks: The Papasula is described not as a new species, but as a new subsppecies: Papasula abbotti costelloi Steadman, Schubel et Pahlavan, 1988. And the number of 2000 species (only Rallidae) is lowered to about 1500, still a lot.

Gallinula spec. nov. remains, as far as I know, undiscribed or it must be Hypotaenidia vekamatolu (Kirchman et Steadman, 2005). David Steadman has many species still to describe, although he did describe
Hypotaenidia ripleyi (Steadman, 1986) from Cook-Islands, Mangaia
Hypotaenidia huiatua (Steadman, Worthy, Anderson et Walter, 2000) from Niue, Anakuli
Hypotaenidia vekamatolu (Kirchman et Steadman, 2005) from Tonga, ‘Eua
Hypotaenidia storrsolsoni (Kirchman et Steadman, 2006) from the Society Islands, Huahine, Fa’ahia
Hypotaenidia temptatus (Kirchman et Steadman, 2006) from the Marianas, Rota
Hypotaenidia pisonii (Kirchman et Steadman, 2006) from the Marianas, Aguiguan
Hypotaenidia pendiculentus (Kirchman et Steadman, 2006) from the Marianas, Tinian
Hypotaenidia ernstmayri (Kirchman et Steadman, 2006) from Micronesia
Hyporaenidia roletti (Kirchman et Steadman, 2007) from Tahuata
Hypotaenidia gracilitibia (Kirchman et Steadman, 2007) from Ua Huka
Hypotaenidia epulare (Kirchman et Steadman, 2007) from Nuku Hiva
Porzana rua Steadman, 1986 from the Cook-Islands, Mangaia
Porphyrio paepae Steadman, 1988 from Tahuata and Hiva Oa
Porphyrio mcnabi Kirchman et Steadman, 2006 from the Society Islands, Huahine, Fa’ahia

Also Trevor Worthy described some Rallidae from Oceania:
Hypotaenidia vavauensis Worthy et Burley, 2019 from Tonga, Vava’u group,
Hypotaenidia steadmani (Worthy et Bollt, 2011) from Austral Islands, Tubuai, Atiahara

Fred

Could it be that this rail was brought by humans to Tonga?

Various birds from the labillardiere expedition, bear a location on the pedestal that is highly unlikely that the specimen was collected here. So besides DNA an isotopical research, if it turns out to be something new is also badly needed (and maybe some information could be extracted).