size comparison between pukeko and takahe

This display was photographed at the Canterbury Museum in Christchurch, NZ. Pukeko is the NZ name for the purple gallinule (Porphyrio porphyrio)

with regards to the photo, the takahe specimen is actually quite small so the size comparison isn't entirely accurate, and also I think its probably fairly old so it has become very dull. In life they are very vibrantly-coloured. The pukeko specimen is more true to life.

With regards to their evolution, there have been at least three purple gallinule colonisations in NZ. The first two resulted in the South Island takahe and the North Island moho, the latter of which was actually larger and more rangy than the surviving takahe. Genetically the two were quite distinct and undoubtably derived from different colonisations at different time periods (formerly they were considered subspecies of one another). While takahe are historically associated with alpine habitats, in pre-human times they were widespread across the entire South Island in all habitats (the present population in the Fiordland mountains is a relict one due to hunting by pre-European Maori).

The pukeko is probably a very recent colonist. There are no pre-human records at all; all skeletal remains found have been only a few hundred years old at most, and the species may have settled here within the last 300 years or so, after Maori opened up more of the country and wiped out some of the competing birds. In appearance they are more or less identical to eastern Australian birds, although they do have some behavioural and reproductive differences.

there are loads of papers on the NZ Porphyrio diversification. One of the earlier ones with regards to reinstating the separate specific identities of North and South Island takahe is "Morphology and evolution of two takahe: flightless rails of New Zealand" by S.A. Trewick in the Journal of Zoology (1996), and it's all followed on from there. I haven't got any of my books with me where I live now, but the Holdaway and Worthy book "The Lost World of the Moa" (2002) will have lots of references in it; if you're interested in NZ pre-human fauna then this book is a must (I just had a quick look on some book sites and can't find any available copies but it is definitely worth getting if you can).

The genus Porphyrio did also spread across the Pacific (as did several other rail genera, particularly Gallirallus) -- I believe David Steadman put a guesstimate figure on extinct Pacific flightless rails at about 3000 species -- although all of that genus are now extinct on the islands apart for the widespread P. porphyrio. There was off the top of my head one large flightless species on Lord Howe Island and one on the Marquesas (the last was possibly seen by Thor Heyerdahl, so it may have survived to at least the late 70s) and I think one on New Caledonia as well.

All that last paragraph was off the top of my head, but here's the Wikipedia list of extinct birds and if you scroll down to rails it lists the named species (for Pacific Porphyrio just the ones I mentioned above): [ame=http://en.wikipedia.org/wiki/List_of_extinct_birds]List of extinct birds - Wikipedia, the free encyclopedia[/ame]


Steadmans' papers are worth reading as well if you can.

this photo shows better the true colour of a takahe: http://www.zoochat.com/1701/takahe-porphyrio-hochstetteri-212550/