Chatham rail

The Chatham rail (Cabalus modestus) is an extinct flightless species of bird in the family Rallidae. It was endemic to Chatham, Mangere and Pitt Islands, in the Chatham archipelago of New Zealand.[2]

Cabalus modestus mount from the collection of Auckland Museum
Illustration from 1907

Chatham rail
Illustration by Keulemans

Extinct  (c.1900)  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Gruiformes
Family: Rallidae
Genus: Cabalus
Species:
†C. modestus
Binomial name
†Cabalus modestus
(Hutton, 1872)
Synonyms

Gallirallus modestus
(Hutton, 1872)
Rallus modestus
(Hutton, 1872)

The Chatham rail and the Dieffenbach's rail, both flightless, were sympatric on the Chatham Islands. Their sympatry suggests parallel evolution after separate colonisation of the Chatham Islands by a common volant ancestor.[3] A genetic analysis from 1997 suggested that the two were sister taxa.[4] However more recent genetic analysis finds them to not be closely related within the Gallirallus radition, with a 2014 analysis finding the Chatham rail being sister taxon to the New Caledonian rail instead.[5]

The Chatham rail was first discovered on Mangere in 1871, and 26 specimens collected there are known from museum collections. It became extinct on the island between 1896 and 1900. The species is also known from 19th century bones from Chatham and Pitt Islands. It is likely to have occurred in scrubland and tussock grass.

Taxidermied chick collected in 1872

Extinction

Its extinction was presumably caused by predation by rats and cats (which were introduced in the 1890s), habitat destruction to provide sheep pasture (which destroyed all the island's bush and tussock grass by 1900), and from grazing by goats and rabbits. On Chatham and Pitt Islands, Olson[6] has suggested that its extinction resulted from competition with the larger Dieffenbach's rail (also extinct), but this has been refuted later when the two species have been shown to have been sympatric on Mangere.[7]

  • Preserved skin
  • Various views of the skull of the Chatham rail
  • Lateral view
  • Dorsal view
  • Ventral view
  • Oblique view

References
  1. BirdLife International (2012). "Cabalus modestus". IUCN Red List of Threatened Species. 2012. Retrieved 26 November 2013.CS1 maint: ref=harv (link)
  2. Marchant and Higgins (1993)
  3. Trewick, S.A. (1997). "Sympatric flightless rails Gallirallus dieffenbachiii and G. modestus on the Chatham Islands, New Zealand; morphometrics and alternative evolutionary scenarios". Journal of the Royal Society of New Zealand. 27 (4): 451–464. doi:10.1080/03014223.1997.9517548.
  4. Trewick SA. 1997. Flightlessness and phylogeny amongst endemic rails (Aves: Rallidae) of the New Zealand region. Philosophical Transactions of the Royal Society. 352:429–446.
  5. Garcia-R, Juan C.; Gibb, Gillian C.; Trewick, Steve A. (December 2014). "Deep global evolutionary radiation in birds: Diversification and trait evolution in the cosmopolitan bird family Rallidae". Molecular Phylogenetics and Evolution. 81: 96–108. doi:10.1016/j.ympev.2014.09.008. PMID 25255711.
  6. Olson (1975c)
  7. Tennyson and Millener (1994)


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