Cabalus

Cabalus is a disputed Oceanian genus of birds in the family Rallidae. Both species placed in the genus here were previously considered part of the genus Gallirallus, one was alternatively placed in Tricholimnas alone or together with the Lord Howe woodhen, and the other was initially included in Rallus.

Species
As delimited here, the genus contains two species, one extinct and another possibly so:


 * New Caledonian rail, Cabalus lafresnayanus (possibly extinct) – formerly in Gallirallus or Tricholimnas
 * †Chatham rail, Cabalus modestus (extinct) – formerly in Gallirallus or Rallus

These species occur on widely separate islands of the southwestern Pacific region; as they are both distinct and singular lineages since at least about 5 million years ago, this may simply mean that they are (or were) the last survivors of a group that formerly spread across the New Zealand region. However, other than being flightless Rallini with a drab brownish coloration, the two species are not much alike, their size difference being vast and running contrary to Bergmann's Rule, and their ecology – though barely studied and certainly restricted by the limited options on their respective island homes – also seems to have been quite different. The New Caledonian rail may in fact belong in Gallirallus (or indeed Tricholimnas); whether it is more closely related to the Chatham rail or to the weka requires further study; analyses of different DNA datasets have yielded inconsistent results. The prehistoric Snipe rail of New Zealand, traditionally separated in a monotypic genus Capellirallus, seems crucial to determine this, as it is in all respects (except for its plumage, which is unknown) quite similar to the Chatham rail, except for being intermediate in size between the two supposed species of Cabalus. It is even possible that the genus Cabalus will eventually be abolished again, since some DNA analyses place the Chatham rail within the large evolutionary radiation of smallish Gallirallus-type species which forms the well-distinct clade Hypotaenidia, and the New Caledonian rail well outside of it.