The possum came for Elvis, a Tokoeka kiwi, late one night on the Milford Track while he sat on his nest. He heard a thump and a crunch, and there it was in the burrow opening, hungry eyes gleaming in the dark. Elvis launched out of the burrow and charged the possum off. It came racing back again, looming towards the nest. Elvis pecked it with his beak and slashed it with his claws. Finally, he unleashed a mighty kick, and the possum scampered off into the night. Read on to see the video of this important Kiwi fightback.
New Zealand is often portrayed as a peaceful, 100% pure, natural wonderland full of dense green forests and the melodic song of hundreds of rare birds. While many protected places are lush and full of bird song, for NZ’s native animals like Elvis, New Zealand is far from peaceful. While Elvis successfully saved himself and his nest that one night on the Milford Track, many kiwi are not so lucky. Alongside habitat degradation and other introduced predators such as rats, ferrets, weasels, and stoats, kiwi have been heroically fighting a human-induced, never-ending battle against the brushtail possum for nearly 200 years.
In the Land Before People
Isolated from other landmasses for millions of years and devoid of mammalian predators, New Zealand’s wildlife evolved in unique ways. With no ground predators, the birds didn’t need to expend energy fleeing in flight, so over time, many evolved to become flightless. With abundant habitats and food sources on the ground, they were able to survive and thrive. One such bird, of course, was the kiwi, and it’s thought to have evolved to fill a habitat and lifestyle that, elsewhere, would have been filled by a mammal.
Kiwi Characteristics and Lifestyle
Thousands of evolutionary years resulted in New Zealand’s five kiwi species: North Island Brown Kiwi, Great Spotted Kiwi, Little Spotted Kiwi, Rowi, and Tokoeka. While separate species, all five share similar strange, non-birdlike characteristics and lifestyles.
Fur-Like Feathers
Kiwi feathers, small and thin, hang loose on their bodies to create, a thick, shaggy, fur-like coat that keeps them warm on the ground.
Heavy Bones
While most other birds have hollow bones filled with air for easy flight, kiwi bones are heavy and filled with marrow. Their legs make up a third of their body weight and allow for quick running on the ground.
Big Babies
Kiwi lay big eggs that take up 20% of the mother’s body, comparable to a human giving birth to a three or four-year-old. Both parents then take turns incubating their eggs for 70-80 days, much longer than most birds, and a similar gestation period to that of a similar-sized mammal. The chicks then hatch fully feathered and can feed themselves, which is rare for birds.
Nocturnal
Kiwi likely evolved to be nocturnal to avoid large, sky-hunting birds like the Haast Eagle, now extinct, as well as for easier foraging at night. Kiwi feed on underground invertebrates that move to the soil surface when the sun goes down. They can then use their nostrils at the end of their beaks to nuzzle the ground and sniff out their food.
Burrow Nests
A male kiwi establishes and defends a territory between two and 100 hectares depending on the species. He will then find a female to follow around until she shows interest. Once bonded, kiwi usually stay together for the rest of their lives. They dig burrows with their legs into the sides of banks and slopes within their territory, then eventually establish a nest in one during mating season, which runs from June - March. At night kiwi pairs often sing duets together.
NZ’s National Icon
All these weird and wonderful characteristics led to the kiwi officially becoming New Zealand’s national bird around 1908. It is so distinct and peculiar, that it became a symbol of NZ’s unique wildlife and the value of our natural heritage.
While the kiwi’s unique characteristics led to its fame and allowed it to flourish in New Zealand’s isolated, pre-human environment for millions of years, a lot of these characteristics also made kiwi extremely vulnerable to the predatory mammals, like possums, that people introduced to New Zealand before anyone knew any better.
People, Pests, and Predators
Humans and Rats
Around 1250–1300 CE Māori became the first people to arrive in Aotearoa, New Zealand. With them came the kiore, the Pacific rat, which reproduced quickly and ate seeds, native vegetation, lizards, and invertebrates, competing with native animals like kiwi and marking the first rapid changes to NZ’s environment caused by introduced mammalian pests and predators. When early European explorers later came to NZ during the 1600s-1800s, they inadvertently brought more rats over on the ships that quickly spread throughout the country.
Domino Disaster
By 1830, settlers were well established in NZ, and they wanted to bring their hunting traditions with them from Europe, so they brought over rabbits. Because rabbit populations can increase ten times over each breeding season, only 40 years later, they reached plague proportions. To control the rabbits, ferrets, stoats, and weasels were introduced, but native birds, like kiwi, were much easier prey.
While the rats, ferrets, stoats, and weasels were chipping away at the forests, hunting the birds, scoffing eggs, and plucking chicks from their nests, people thought New Zealand was also in need of a good fur trade. So in 1837, the brushtail possum was brought over from Australia. The first introduction attempt wasn’t successful, but more attempts were made. As opportunistic creatures, the possums were soon able to adapt, quickly taking advantage of the vegetation, seeds, birds, and eggs, and establishing booming populations throughout New Zealand.
A Daily Survival Struggle
Today, there are an estimated 30 million possums throughout the country, around 430 possums for every one kiwi. Years of habitat clearance and the onslaught of possum attacks, along with attacks from other introduced mammals, have led to most of NZ’s unique native species, like kiwi, now being threatened with extinction.
Reliant on native vegetation for shelter, invertebrates for food, and unable to fly away, kiwi numbers have dwindled in the face of food and habitat competition and never-ending predator attacks. Predators like stoats and ferrets can happily hunt birds day or night, and possums are nocturnal like kiwi, so no matter the time of day, there’s always something ready to attack. We have gone from an estimated 12 million kiwi before human arrival, to around 70 thousand total kiwi today. Kiwi populations outside of extensive predator control areas decline by 2% annually, which equates to losing around 20 kiwi every week.
When You Know Better, Do Better
Luckily, we are now well aware of our mammalian mistakes, and there are multiple conservation strategies in place to help our struggling native species like the kiwi. While you won’t see a kiwi out on a Milford Sound tour, partially due to their nocturnal lifestyle, largely due to it not yet being safe enough to build up big enough numbers in the area just yet, you’ll likely see evidence of some of the conservation efforts in place to help save our native birds, like kiwi, while you’re traveling Milford Road.
Trapping
Predator trapping is crucial for controlling the populations of introduced predators like possums. There are trapping programmes throughout the country, and you’ll likely see traps alongside tracks in Fiordland National Park.
1080 Drops
1080 is a poison in biodegradable pellets that is primarily dropped in remote, hard-to-reach places throughout New Zealand where trapping is difficult or impossible. Aerial drops via helicopter are the main method of distribution, and you may see one of these helicopters in the distance while on a Milford Sound tour, as Fiordland has many areas that are hard to reach on foot.
Protected Areas and Sanctuaries
There are several kiwi sanctuaries throughout the country, which are areas where extensive predator trapping occurs. In National Parks, like Fiordland National Park, predator control and habitat protection also allow some kiwi to survive in the wild. There are also several predator-free Islands where populations of kiwi can thrive, as well as ecosanctuaries, where large, predator-proof fences protect native forests and animals like kiwi.
Operation Nest Egg
Kiwi chicks hatched in the wild only have a 10% chance of surviving to adulthood. Under Operation Nest Egg, kiwi eggs are taken from the wild, hatched in captivity, and then the chicks are raised in “kiwi crèche” sites, often inside eco-sanctuaries, until they are 1-1.2 kg. At this size, they are big enough to defend themselves from predators, and with this operation, kiwi chicks have a 65% chance of surviving to adulthood.
A Fighting Chance
Kiwi are often thought of as timid, feeble little creatures who need so much protection because they simply can’t defend themselves. But don’t let their cute, fuzzy bodies fool you. What they lack in wing power, they make up for in leg strength. Like Elvis the Fiordland tokoeka, many adult kiwis are quite capable of pummelling a possum when they need to. See footage of Elvis defeating the possum below 👇
The trouble is, their chicks aren’t big enough to defend themselves, and adul kiwi don’t have the capacity to fight off predators all day every day. It’s estimated that without protection and predator control, some kiwi species would be extinct within two generations. But with ongoing predator control efforts, protecting native habitats, and helping chicks survive their first few months of life, we’re now working hard to address our past mistakes and helping to support New Zealand’s national icon in their battle against predators like the possum. Populations of kiwi in some protected areas are now reaching numbers where we’re having to move them to new areas to avoid overcrowding, which is a great sign we’re moving in the right direction.
From the nocturnal skirmishes on the Milford Track to the broader battlegrounds of predator-infested forests, the kiwi’s survival struggle reflects both the resilience of nature and the consequences of human action. Fortunately, conservation efforts are now giving kiwi a fighting chance against relentless adversaries like the possum.
The story of the kiwi serves as a reminder of our responsibility to protect native wildlife and their habitats. By learning from past mistakes and embracing conservation measures, there is hope that kiwi like Elvis can continue sitting on their nests and dueting with their mates in moonlit forests for many generations to come.