Q. What were the biggest birds in the world? I have heard that some extinct ones were taller than ostriches.
A. Ostriches reign as the largest birds on earth today. But once upon a time there lived birds that grew 2 feet taller than any NBA player. They dwelt in New Zealand in the 1300s, and they did not live happily ever after. A study conducted around 1999 provided a disquieting revelation of how quickly humans can drive an animal species to extinction. The study about the enormous flightless birds known as moas confirms that a small number of people can eliminate a large number of animals in a short period of time. That humans can drive other species to extinction comes as no surprise. How quickly the moas became extinct did come as a surprise to the New Zealand scientists conducting the study. Their findings offer a lesson to us all.
Moas were the biggest birds ever known to have lived on earth. Some were almost 10 feet tall. Unable to fly, moas used their enormous legs to move around like today’s African ostriches and Australian emus. One value of flight is the ability to escape ground predators. Moas had successfully evolved on the islands of New Zealand by being able to fend off most natural predators without flying. Then came the Polynesian settlers known as Maoris.
The Maoris arrived in New Zealand around the 1200s. By the time Columbus reached America, all species of giant moas had been extinct for a century. The big birds had never encountered such a relentless land predator. The Maoris could easily capture and kill them. And they did.
The scientists conducting the study used a variety of data to make their determinations with mathematical models that simulated the sequence of events. Human colonization rates and the level of exploitation of birds were determined by radiocarbon dating and by examining Maori hunting sites, which contained moa remains. From this information, an estimate of 100 Maori settlers was used to approximate the increase in human population size and rate of habitat loss on the islands. The model was based on an estimated 158,000 moas living in New Zealand at the time of human settlement. The predicted rates of decline of moas were then determined in a variety of hypothetical scenarios leading to their extinction.
The maximum time for all of the giant moas in New Zealand to go extinct would not have exceeded 160 years even without a loss of moa habitat and with the assumption that Maoris did not eat moa eggs. However, moa habitat loss did occur, and when an omelet big enough to feed a family was in the offing, moa eggs were undoubtedly on the menu.
The significance of the study is not that we can pin the loss of a fabulous group of birds on the Maoris. Colonists in every part of the world have been guilty of eliminating species that had no recourse against human predators. The important point is that humans could eliminate moas so quickly. Flightless birds known as kiwis still scramble around in the New Zealand undergrowth. Being small and of little importance to anyone over the ages has ensured their survival. The giant, flightless moas met a different fate.
The lesson for us in modern times is that small numbers of humans can still eliminate species simply by removing them from their native habitats. Exploitation for commercial profit for the restaurant trade, the pet trade or bogus medical purposes can quickly bring some species to extinction, including many of today’s birds and reptiles, as well as whales and other large, long-lived mammals that cannot sustain high adult mortality rates. The message from the moas is clear: On our current trajectory, a small proportion of the world’s human population will eliminate some of our remaining large species within our lifetimes. We should not allow this to happen.