Secondly, radiocarbon-dated bird bones from dated Maori archaeological sites prove that all known moa species were still present in abundance when the first Maoris stepped ashore. So were the extinct goose, duck, swan, eagle, and other birds now known only from fossil bones. Within a few centuries, the moas and most of those other birds were extinct. It would have been an incredible coincidence if every individual of dozens of species that had occupied New Zealand for millions of years chose the precise geological moment of human arrival as the occasion to drop dead in synchrony.
Finally, more than a hundred large archaeological sites are known—some of them covering dozens of acres—where Maoris cut up prodigious numbers of moas, cooked them in earth ovens, and discarded the remains. They ate the meat, used the skins for clothing, fashioned bones into fishhooks and jewellery, and blew out the eggs for use as water containers. During the Nineteenth Century moa bones were carted away from these sites by the wagonload. The number of moa skeletons in known Maori moa-hunter sites is estimated to be between 100,000 and 500,000, about ten times the number of moas likely to have been alive in New Zealand at any instant. Maoris must have been slaughtering moas for many generations.
Hence it is now clear that Maoris exterminated moas, at least partly by killing them, partly by robbing their nests of eggs, and probably partly as well by clearing some of the forests in which moas lived. Anyone who has hiked in New Zealand's rugged mountains will initially be incredulous at this thought. Just picture those travel posters of New Zealand's fiordland, with its steep-walled gorges 10,000 feet deep, its 400 inches of annual rainfall, and its cold winters. Even today, full-time professional hunters armed with telescopic rifles and operating from helicopters cannot control the numbers of deer in those mountains. How could the few thousand Maoris living on New Zealand's South Island and Stewart Island, armed only with stone axes and clubs and operating on foot, have hunted down the last moas?
But there would have been a crucial difference between deer and moas. Ueers have been selected for tens of thousands of generations to flee from human hunters, while moas had never seen humans until Maoris arrived. Like the naive animals of the Galapagos Islands today, moas were probably tame enough for a hunter to walk up to one and club it. Unlike deer, moas may have had such low reproductive rates that a few hunters visiting a valley only once every couple of years could kill moas faster than they could breed. That is precisely what is happening today to New Guinea's largest surviving native mammal, a tree kangaroo in the remote Bewani Mountains. In areas settled by people, tree kangaroos are nocturnal, incredibly shy, live in trees, and are far harder to hunt than moas would have been. Despite all that, and despite the very low human population of the Bewanis, the cumulative effects of occasional hunting parties—literally one visit per valley per several years—have sufficed to bring this kangaroo to the verge of extinction. Having seen it happen to tree kangaroos, I now have no difficulty understanding how it happened to moas.
Not only moas, but also all of New Zealand's other extinct bird species, were still alive when Maoris landed. Most were gone a few centuries later. The larger ones—the swan and pelican, the flightless goose and coot—were surely hunted for food. The giant eagle, however, may have been killed by Maoris in self-defence. What do you think happened when that eagle, specialized at crippling and killing two-legged prey between three and ten feet tall, saw its first six-foot-tall Maoris? Even today, Manchurian eagles trained for hunting occasionally kill their human handlers, but the Manchurian birds were mere dwarfs beside New Zealand's giant, which was pre-adapted to become a man-killer.
Surely, though, neither self-defence nor hunting for food explains the rapid disappearance of New Zealand's peculiar crickets, snails, wrens, and bats. Why were so many of those species exterminated, either throughout their range or else everywhere except on some offshore islands?
Deforestation may be part of the answer, but the major reason was the other hunters that Maoris intentionally or accidentally brought with them—rats! Just as moas that evolved in the absence of humans were defenceless against humans, so, too, small insular animals that evolved in the absence of rats were defenceless against rats. We know that the rat species spread by Europeans played a major role in modern exterminations of many bird species on Hawaii and other previously rat-free oceanic islands. For example, when rats finally reached Big South Cape Island off New Zealand in 1962, they exterminated or decimated the populations of eight bird species and a bat within three years. That is why so many New Zealand species are restricted today to rat-free islands, the sole places where they could survive when the tide of rats accompanying the Maoris swept over the New Zealand mainland.
When the Maoris landed, they found an intact New Zealand biota of creatures so strange that we would dismiss them as science-fiction fantasies if we did not have their fossilized bones to convince us of their former existence. The scene was as close as we will ever get to what we might see if we could reach another fertile planet on which life had evolved. Within a short time, much of that community had collapsed in a biological holocaust, and some of the remaining community collapsed in a second holocaust following the arrival of Europeans. The end result is that New Zealand today has about half of the bird species that greeted the Maoris, and many of the survivors are either now at risk of extinction or else confined to islands with few introduced mammalian pests. A few centuries of hunting had sufficed to end millions of years of moa history. Not only on New Zealand but on all other remote Pacific islands where archaeologists have looked recently in Polynesia, bones of many now-extinct bird species have been found at sites of the first settlers, proving there that the bird extinctions and human colonizations were somehow related. From all the main islands of Hawaii, paleontologists Storrs Olson and Helen James of the Smithsonian Institution have identified fossil bird species which disappeared during the Polynesian settlement that began around 500 AD. The fossils include not only small honey-creepers related to species still present but also bizarre flightless geese and ibises with no living close relatives at all. While Hawaii is notorious for its bird extinctions following European settlement, this earlier extinction wave had been unknown until Olson and James began publishing their discoveries in 1982. The known extinctions of Hawaiian birds before Captain Cook's arrival now total the incredible number of at least fifty species, nearly one-tenth of the number of bird species breeding on mainland North America.
That is not to say that all these Hawaiian birds were hunted out of existence. Although geese probably were indeed exterminated by overhunting, like the moas, small songbirds are more likely to have been eliminated by rats that arrived with the first Hawaiians, or else by destruction of forests that Hawaiians cleared for agriculture. Similar discoveries of extinct birds at archaeological sites of early Polynesians have also been made on Tahiti, Fiji, Tonga, New Caledonia, the Marquesas Islands, Chatham Islands, Cook Islands, Solomon Islands, and Bismarck Archipelago.