Small New Zealand Kiwi Genetically Closest to 10-Foot Elephant Bird
New Zealand's iconic kiwi bird apparently once flew and is most related to the 10-foot elephant bird from Madagascar, not the Australian emu, according to new research from the University of Adelaide in South Australia.
Scientists now believe that not only did the kiwi not originate in Australia, but sometime in the distant past it flew to its current island habitat.
Instead, the diminutive kiwi is most closely related to the extinct Madagascan elephant bird -- a 2-3 metre tall, 275 kg giant. And surprisingly, the study concluded, both of these flightless birds once flew.
Conducted by the university's Australian Centre for Ancient DNA and published in the journal Science, the study -- aside from revealing some surprising facts about the chicken-sized kiwi -- also claims to have solved a long-standing mystery about the evolution of the giant flightless birds like the emu and ostrich, as well as extinct giant moa of New Zealand and elephant birds of Madagascar, which were and still are found across the southern continents.
Scientists previously held that the flightless development of the various species of giant birds developed in connection with the isolation they experienced as the continents separated over that last 130 million years or so.
But, ancient DNA extracted from bones of two elephant birds held by the Museum of New Zealand proved a close genetic connection with the kiwi, regardless of the significant differences in geography, morphology and ecology between them.
"This result was about as unexpected as you could get," said Kieren Mitchell, a doctoral candidate with the ACAD who performed much of the investigative work. "New Zealand and Madagascar were only ever distantly physically joined via Antarctica and Australia, so this result shows the ratites must have dispersed around the world by flight."
Alan Cooper, the ACAD's current director whose work in the 1990s concluded the closest living relatives of the kiwi were the Australian emu and cassowary, welcomed the new findings.
"It's great to finally set the record straight, as New Zealanders were shocked and dismayed to find that the national bird appeared to be an Australian immigrant," said Cooper. "I can only apologize it has taken so long!"
The research team used the elephant bird DNA to figure out when the giant flightless birds "dispersed around the world right after the dinosaurs went extinct, before the mammals dramatically increased in size and became the dominant group," Cooper said..
"We think the ratites exploited that narrow window of opportunity to become large herbivores, but once mammals also got large, about 50 million years ago, no other bird could try that idea again unless they were on a mammal free island -- like the Dodo."
Cooper added the new study also explains "why the kiwi remained small. By the time it arrived in New Zealand, the large herbivore role was already taken by the moa, forcing the kiwi to stay small, and become insectivorous and nocturnal."