Stories from bird bones

Kea

Kea

Most of us associate kea with holidays in the Southern Alps. When you stop the car at Arthur’s Pass a few of these parrots will normally arrive to fearlessly beg for food. Cars and food are so strongly associated in their minds that they’ll tear the rubber trim off your vehicle in the hope that snacks might be found somewhere inside. Kea are remarkable birds, intelligent and inquisitive, and are famous among ornithologists for being the world’s only alpine parrot.

To a palaeontologist, though, kea aren’t alpine parrots at all. Fossil kea bones, many just a few hundred years old, have been found in lowland sites thoughout Canterbury and Otago right down to the coastline, showing the birds were living in coastal forest before humans arrive. Even today, kea live year-round in forest in parts of the West Coast. And new research has identified kea bones from swamps and sand dunes in Hawkes Bay and the Wairarapa, so it seems likely that were living in North Island forests as well.

Kea, Kākā, and Chatham Kākā  skulls

Kea, Kākā, and Chatham Kākā skulls

So where did all the kea go? They were probably wiped out by the first human settlers and the rats that accompanied them around 700 years ago, disappearing from the North Island and most of the South Island. The only reason kea aren’t extinct is that the Southern Alps are inhospitable to both rats and humans. But the upside is that kea could likely be reintroduced to North Island forests where there’s sufficient predator control—good news for mainland islands like Zealandia and Bushy Park.

Huia

Huia

Kea are not the only case where fossil bones tell us where a species used to live. Huia at the time of European settlement were restricted to the south-eastern North Island, mostly in the Tararua, Ruahine, and Rimutaka ranges. But their bones have been found right up to Northland, and they were probably found throughout the island before human hunting made them rare (and, by about the 1920s, made them extinct).

Takahē were once found throughout the South Island. Thought to be extinct by the 20th century, they were famously rediscovered in an Fiordland valley in 1948. Their northern cousin, the moho or mohoau, is known only from fossil bones from all over the North Island, although a single live bird was caught in the Tararuas in 1894. Both takahē and moho were the giant flightless descendants of pukeko, and both were driven almost to extinction in pre-European times; it’s just a fluke that the South Island takahē managed to survive while their relatives went extinct. Like the kea, takahē persisted in an inhospitable environment, but they much prefer living in lowland forests, given how well they do on offshore islands and mainland sanctuaries.

Chatham Kākā

Chatham Kākā

Fossils not only shed light on living species; they sometimes reveal brand new ones. For years, palaeontologists had been turning up bones of kākā in the Chatham Islands, except these kākā had unusually long beaks; almost as long as a kea’s. After comparing bones, they realised the Chatham kākā was a completely separate species: a ground-dwelling version of the mainland kākā, wiped out soon after humans arrived in the Chathams. The Chatham Islands turn out to been like mainland New Zealand in miniature, full of species found nowhere else. The islands had their own species of pigeon, robin, fernbird, penguin, bellbird, swan, coot, and other flightless rails; most of these are now extinct or endangered, a few, like the Black Robin, were rescued in the nick of time.

Kākā

Kākā

It’s remarkable that we’re still making discoveries about some of our most well-known native birds, from such inconspicuous things as tiny fossils. Only a handful of scientists are doing this work, and it’s not well-supported—some of our palaeontologists have had to move to Australia to get funding. It’s taken years for conservation workers to incorporate fossil evidence into decisions about which species should be translocated where. But it’s important that institutions like museums keep doing it: a large part of the prehistory of New Zealand is a story told by little bones.

 

Dr Mike Dickison is the Curator of Natural History at the Whanganui Regional Museum.

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