Kapiti is a small island off the western coast of New Zealand that until 1992 was inhabited by a large population of sheep and goats and of course the farm families who tended them as well as the animals that are universally found around human habitation: dogs, cats, and rats.
In 1992 the local farmers were bought out and left Kapiti taking their animals with them. The island's population of rats and other predators such as ferrets and weasels were trapped or poisoned.
The removal from Kapiti of human settlements and their interacting organisms is part of an ongoing and ambitious effort to restore, at least part of the unique New Zealand ecosystem, one that had evolved without disturbance until about 1250 A.D. when the first humans began to settle New Zealand.
The Kapiti story begins on the ancient super-continent of Gondwana 85 million years ago when the part of the super-continent which would become New Zealand broke free.
Over the next 30 million years, the movement of tectonic plates would continue the breakup of Gondwana, moving the pieces to their present locations with New Zealand surrounded by an ocean barrier 2,000 kilometers wide between it and Australia.
There it would left undisturbed by humans but still subject for the next 50 million years to the “staggeringly improbable...and utterly unpredictable and quite unrepeatable” events of evolution. (Gould, 1989)
One of those unpredictable events, thought to have been earth’s collision with an asteroid, was the great Cretaceous-Paleogene extinction that occurred about 65 million years ago. The event caused a mass extinction of three-fourths earth’s plant and animal species including of course all of the non-avian dinosaurs.
The disaster for the dinosaurs and so many other organisms created new opportunities to survivors, particularly mammals. Mammalian species flourished across the earth with new species like whales and primates appearing nearly but not everywhere on earth.
New Zealand with its 2,000 km. salt water barrier was closed any new organism that couldn’t be blown, float, fly or swim there. This explains New Zealand’s endemism, the number of species that are unique to a specific geographic location. New Zealand’s endemic species include its bats, amphibians, reptiles, as well as 70 percent of New Zealand’s land and sea birds, 80 percent of its plants, 90 percent of its freshwater fish, insects and mollusks.
So when the first humans to arrive in New Zealand, the Maori, they found the islands a paradise of birds. Perhaps 300 species of birds filled the forests with birdsong. Sir Joseph Banks, who served as naturalist on Captain Cook’s 1769 voyage, wrote in his journal (17 January 1770):
This morn I was awakd by the singing of the birds ashore from whence we are distant not a quarter of a mile, the numbers of them were certainly very great who seemd to strain their throats with emulation perhaps; their voices were certainly the most melodious wild musick I have ever heard, almost imitating small bells but with the most tuneable silver sound imaginable to which maybe the distance was no small addition. On enquiring of our people I was told that they have had observd them ever since we have been here, and that they begin to sing at about 1 or 2 in the morn and continue till sunrise, after which they are silent all day like our nightingales.
The absence mammals opened niches filled by mammals in other ecosystem, were occupied by birds in New Zealand, many of birds were flightless and some of them were very large.
The iconic New Zealand, the Kiwi uses its keen sense of smell to find its insect prey and its powerful digging feet are well-adapted to get at them, very much like a badger.
The giant Moas grazed like a feathered, two-legged cow, stalked, not by a lions or tigers but by a huge eagle (and now extinct) eagle.
The appearance of humans with their companions, rats, dogs had an immediate impact on the native bird populations.
Within a century and a half of the first human arrival New Zealand’s new resident primate had hunted the Moa into extinction. Without their Moa prey, the eagles disappeared as well. Among the non-human mammals, dogs and rats found that the birds, flightless and nesting on the ground, easy prey. The rats, prolific breeders and with no natural enemies flourished on a diet not only of small flightless birds but also frogs, lizards, invertebrates.
By the middle of the twentieth century, what remained of the New Zealand forests were largely silent; there were few native birds left to sing.
Beginning in 1960 the first of New Zealand’s many coastal islands was cleared of rats by volunteers. By 2020 more than 110 New Zealand islands (like Kapiti) have been freed of bird predators. While much of the work is done by volunteers, the efforts are now fully supported by both local and the national government. The lessons learned during the clearing of New Zealand’s islands are now being applied to the mainland where pest-free sanctuaries have been created. One of these, Zealandia can be found right in New Zealand’s capital city Wellington.
In 2015 the New Zealand government created a charity named Predator Free 2015 Ltd. The charity directs Crown investment to clear New Zealand forests of stoats, rats, and possum by 2050.
In the brief time span of 180 years since 1840 when the first ships brought settlers from Great Britain, data from New Zealand government sources indicate that 4,000 native species whose long-term survival is threatened with extinction.
The forces of evolution create the ecological communities. We humans are very good at disrupting the ecology but we are not very good at creating them. Our efforts to improve things are often misguided. We hunt wolves to extinction and create a plague of deer and coyotes.
Predator Free aims at recovering its native bird population so that in the near future New Zealanders will awake to the sound that Sir Joseph Banks described in 1770.
The cynic will certainly ask “what could go wrong?”
The outcome will depend on how well we use what we know about the natural world.
Kapiti Island. Kapiti Island Nature Reserve. Department of Conservation www.doc.govt.nz/kapitivisits
Gould, S.J. (1989). Wonderful Life: The Burgess Shale and the Nature of History. W.W. Norton & Company, New York.
The New Zealand Department of Conservation’s Website https://www.doc.govt.nz is a rich source of information New Zealand past and present.
The photo on page 1 was taken on Kapiti Island in January 2020, by the author.
Dr. John HOlton
Dr. John Holton joined the S²TEM Centers SC in July of 2013, as a research associate with an emphasis on the STEM literature including state and local STEM plans from around the nation.