The Chatham Island kaka is known only from fossil bones a few thousand years old on the Chatham Islands. Its remains were first collected in the late 19th Century. However, ever since then there has been confusion about which species these bones represented, with suggestions that they may have been from either kea or kaka. The possibility that the bones could represent an undescribed species was first raised in the 1990s and the Chatham species was described formerly in 2014. Today one species of kaka survives on mainland New Zealand but until the early 1800s a third species occurred on Norfolk Island, to the north-west of New Zealand. DNA analyses suggest that the Chatham Island parrot originated from a kaka that flew to the island group around 1.7 million years ago. This was probably not long after the islands emerged above sea level. Little is known about the Chatham kaka as it became extinct in prehistoric times.
The Chatham Island kaka was a similar overall size to the mainland New Zealand kaka but larger than the extinct Norfolk Island species. The Chatham Island species may have looked superficially like a mainland kaka, except that its beak length was halfway between the short beak of the kaka and the long beak of the kea. It also had relatively large thigh bones and a broad pelvis. Nothing is known about the plumage of the Chatham Island form.
Distribution and habitat
Fossils of the Chatham Island kaka have been found on main Chatham, Pitt and Mangere Islands, so it was probably present on other vegetated islands such as Little Mangere and Rangatira Islands too. The sites where its bones have been found are in widespread locations suggesting that the species was somewhat of a generalist but presumably it would have mainly inhabited forests, which were widespread on the island group in pre-human times.
Fossils suggest that the Chatham Island kaka was once widespread and fairly common throughout the Chatham Island group.
Threats and conservation
The Chatham Island kaka became extinct in prehistoric times, and no records of live birds exist. A few bones have been found in human food middens, and hunting for food by people is probably the primary cause of the species’ demise, although habitat clearance and predation by Pacific rats may have contributed.
Nothing is known about the breeding habits of the Chatham Island kaka.
Behaviour and ecology
The relatively large thigh bones and broad pelvis suggest that the Chatham Island kaka spent more time walking around on the ground than its mainland cousin. However it was still capable of flight.
Presumably, like its mainland relatives, the Chatham Island kaka ate seeds, fruit, nectar and invertebrates. Stable isotope analyses of Chatham Island kaka bones indicate that the Chatham birds were mainly herbivorous.
Wood, J.R.; Mitchell, K.J.; Scofield, R.P.; Tennyson, A.J.D.; Fidler, A.E.; Wilmshurst, J.M.; Llamas, B.; Cooper, A. 2014. An extinct nestorid parrot (Aves, Psittaciformes, Nestoridae) from the Chatham Islands, New Zealand. Zoological Journal of the Linnean Society 172: 185-199.
Tennyson, A.J.D. 2015. Chatham Island kaka. In Miskelly, C.M. (ed.) New Zealand Birds Online.www.nzbirdsonline.org.nz
Chatham Island kaka
- Breeding season
- Egg laying dates