The moas of New Zealand were the largest true birds that ever lived. They were preyed upon by an eagle that was itself so large it probaby ate the first human settlers, the Maori, as well– they have legends saying so, and pictured it on rocks. As in so many places, humans probably put an end to the big birds and its predator– aboriginal humans are as efficient as any others at that practice. Aussie zoologist Tim Flannery calls it the “Black Hole Theory” of extinction, said hole being the human digestive system…
A new story from Yahoo News Service suggests why moas were so vulnerable (other than being huge and slow):
“….how did a small Maori population, armed only with close-range wooden weapons and traps, wipe out such a plentiful species in such a large country?
The answer, according to the new research, may be found in growth rings in the bones of these extinct giants.
These marks are common in many animal species and are caused by differing growth rates in changing seasons. But bird species do not have these rings as in most cases their growth phase is confined to less than a year.
The moa, though, was the exception.
Examination of rings in stored bones suggest that the two moa species, luxuriating in the safety of New Zealand’s unique eco-system, may have taken several years to reach reproductive maturity and up to a decade to attain skeletal maturity.
That made them “extremely vulnerable” to hunting. If too many adult moa were caught too quickly there would have been no chance of replenishment, and the species, dominated by unreproductive birds, would have been placed under severe pressure.”
This is bigger scientifically than it seems. It makes moas more like mammals– or dinosaurs. Virtually every bird attains full size in a year, and only a few longer- lived groups take longer than that to attain sexual maturity. And they usually do it in that order…