Their sympatry suggests parallel evolution after separate colonisation of the Chatham Islands by different rail ancestors.

[5] However more recent genetic analysis finds them to not be closely related within the Gallirallus radiation, with a 2014 analysis finding the Chatham Islands rail being sister taxon to the possibly extinct New Caledonian rail instead.

The species is also known from 19th century bones from Chatham and Pitt Islands.

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 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.