Enter people. Amazing ocean voyagers from Polynesia — now known as the Maori — discovered what we now call New Zealand only about 750 years ago, the latest human colonization of any major land mass on earth. And they were hungry after a very long trip. Moas and other birds that could not fly away were both tasty and relatively easy to obtain for food and ornamentation. Scientists now believe that it too Maori only about a century to hunt the ten or so moa species to extinction (Haast eagles soon followed). Maori also brought mammals to their new land, most prominently Polynesian rats. And rats love to eat eggs and baby birds. A big blow to endemic birds.
Things only got (much) worse when Europeans showed up on the scene. Even famed navigator James Cook, among the first European explorers to visit New Zealand, thought a few sheep could improve the place, so he released a couple on the South Island in 1777. A few decades later, however, English sheep farmers arrived in droves. They found islands covered in a variety of amazing native forests, which they mostly logged and cleared to create pastureland. Eliminating over 80% of native forest cover obviously spelled the end for many of the country’s birds. But then things even went downhill from there. Wanting familiar animals for food and sport, early European settlers introduced rabbits in the early 1800s, which promptly reproduced like, well, you-know-what until the countryside was overrun. The critters’ consumption of things that otherwise could be eaten by sheep did not please farmers, and despite dire warnings from ornothologists such as Walter Buller, in the 1880s officials decided to introduce stoats (a sort of weasel) in an effort to control the rabbit population.
Stoats are basically the perfect bird-killing machine; they love to eat eggs and young birds, and their climbing and burrowing ability allows them to go almost everywhere (they also eat tuataras). And like the species they were supposed to (but did not) eliminate, stoats are prodigious breeders. Roving males and even the fathers of young stoats breed with female juveniles, who then are pregnant when they first leave the nest where they were born. And even though some of New Zealand’s native forest is regrowing, it is now overrun with stoats. The Department of Conservation is trying desperately to kill the critters; even the warden in one of the huts where we stayed while hiking hit up his nightly guests for contributions to his own stoat trap purchase and placement program to benefit the forest birds along nearby trails. Narrow rectangular stoat traps are ubiquitous on New Zealand forest paths; on the famous Routeburn Track we saw a trap every 100 meters or so.
And stoats are not even the only bane of native birds and other species’ very existence. Possums introduced from Australia – the cute kind, not their uncharismatic distant North American cousins – will eat just about anything, including prodigious amounts of native vegetation as well as the eggs and young of native birds and reptiles. So everyone gets in on the act of killing possums (an extermination campaign which no doubt makes Kiwis’ mates from across the Tasman Sea a bit uncomfortable, since possums are both protected and the subject of popular children’s books in Australia). The national museum in Wellington features a video with schoolkids happily holding up possums they’d shot as part of a school-sponsored project. There are competitions with prizes for shooting the most possums, and even contests for the best-dressed dead possum. New Zealand’s wool industry has even created a blend of fine merino wool and possum fur (which is a very nice combination that produces clothing items that are soft, warm, and light) to create economic rewards for killing possums. But like stoats, the tide of possums that has overrun islands with excellent habitat and no predators is almost impossible to hold back.
The results of habitat loss and particularly the consequences stemming from predator introductions have been devastating. New Zealand has lost about half of the birds that existed on the islands when the first humans arrived, but even that statistic is misleading. One of the few truly successful conservation tactics in the country has been to select an island – other than the two main islands – where mammalian predators were either never introduced or where managers have relentlessly poisoned and trapped them out of existence. Mangers then use these “bird-safe” islands as a place to reintroduce bird populations, or to serve as a sort of nursery where juvenile birds (such as young kiwis) can be released, then recaptured and released back into areas on the mainland when they are larger and can better fight off stoats and possums.
We witnessed firsthand the dramatic differences between what New Zealand’s bird population is and what it could be. In our many kilometers of hiking through some of the country’s most intact remaining forests, we seldom saw many birds – despite earnestly looking – and we typically walked in almost eerie silence. But near Auckland we visited the Tiri Tiri Mitangie Open Reserve, an island only a couple of kilometers offshore from one of the city’s suburbs. For years the 600 or so acre island was a sheep pasture, but the government canceled the farmer’s lease in the 1970s. After a massive pest eradication effort, and an even more massive native vegetation planting effort by community volunteers coordinated by a NGO “friends” group, the island is today a sort of miniature native bird paradise. Almost immediately upon starting along the island’s trails with our volunteer guide, we heard a relative cacophony of birdsong. And sightings of otherwise rare birds were common, including northern island robins, stitch-birds, [saddle back, and blue crows]. We even saw two takahes and their chick, among the 300 or so individuals of their species left on the planet. A flightless bird somewhat reminiscent of a dodo, scientists though takahes were extinct until a small population was discovered in a remote area of the South Island in 1948. In an effort to ensure that a disease or other disastrous event could not wipe out the entire species, the Department of Conservation has moved some individual takahes to a few safe places around the country, including Tiri Tiri Metangi even though the species never occurred so far north.
But our experiences on Tiri Tiri raise some interesting questions. If I were the type of bird enthusiast who keeps a life list of birds I’ve seen in the wild, could I add stitch-birds to my list? While these birds may have once occurred on the island, their existence there today is solely due to the intensive restoration and reintroduction efforts of the New Zealand government and dedicated volunteers, who continue to encourage growth of the population in part with supplemental feeding stations. And what about takahes? They are “wild-ish” in that they roam freely around on Tiri Tiri Matengi – conveniently for visitors, they like to graze on the grasses near the island’s visitor center – but they are outside their native habitat, individually known and studied, banded, closely monitored, and carefully protected. So are they wild birds? Are they in a sort of zoo or research facility? And perhaps the bigger question – is this the future of biodiversity? Is there much of a difference between takahes and “wild” California condors that are almost constantly monitored by biologists and recaptured and detoxified when they (almost inevitably at some point in their lives) ingest an otherwise lethal dose of lead after feeding on a carcass contaminated with lead bullet fragments? Or what about wolves in the western United States, which the U.S. Fish and Wildlife Service calls “recovered” even though managers may literally have to truck a few individuals back and forth among isolated small populations in order to maintain the species’ genetic diversity over the long term? What is a “recovered” population? What is a zoo? What is “wild” and how much are we willing to do to keep or restore truly wild populations? What do we want?
