New Zealand Kiwi – A TRULY UNIQUE BIRD
Kiwi Recovery Programme
What an unusual creature!
Unique to New Zealand , the kiwi is a very unusual bird. The discovery by Europeans, of this flightless, nocturnal, burrowing bird in New Zealand was originally thought to be a hoax,
Kiwi are recognised as one of the world's most unusual birds. They are entirely flightless, having only small vestigial wings and share traits with both bird and mammal species.
Perfectly adapted to their niche
The kiwi, as with any species, evolved to fill specific niches in the ecosystem. New Zealand evolved as an island without predatory land mammals, far away from any other landmass. Originally, not even mice and rats were found in New Zealand .
Birds and reptiles evolved to fill the ‘gaps' in the ecosystem, which would have normally been taken by small mammals and rodents. Many New Zealand birds are flightless, or not strong fliers, instead having well developed legs to run across the forest floor. Many of our unique creatures are also nocturnal or live in burrows, all traits more to be expected in small mammal species.
Kiwi are omnivorous, eating a large variety of insects, grubs, berries, fruits, shoots and leafy material, which are all readily found on the forest floor. They also swallow small stones, which stay in the birds ‘gizzard' (first part of the kiwi digestive system). These stones help by grinding the fibrous food eaten by the kiwi, making it easier to digest.
Ko kiwi rerega kore, tu maro ana ki te riri
– Kiwi, flightless, but staunch in battle
The kiwi is one of New Zealand 's most ancient birds. They evolved up to 70 million years ago, thriving at ground level where there were no predatory mammals to hunt them.
The kiwi is of immense spiritual, cultural and traditional importance to Maori. Ngai Tahu holds manawhenua (tribal authority) over most of Te Waipounamu ( South Island ). This is recognised under the Ngai Tahu Claims Settlement Act (1998), which categorises the Roroa (Great Spotted Kiwi) and Rowi (Okarito Brown Kiwi) as taonga (prized possessions). According to Maori tradition, the kiwi is the eldest child of Tane Mahuta (God of the Forest ). In Maori culture this means that ‘kiwi are our elder brothers and sisters'.
Ngai Tahu hunted kiwi for their meat and feathers. Kiwi meat was even referred to as the ‘food of chiefs' among some tribes. Kiwi feathers, bone and leathery skin were used to make textiles and other commonly used articles.
Many rituals and prohibitions surrounded the traditional hunting of kiwi by Maori. During the hunting season, Maori hunting parties had to take great care not to break Tapu (placement of spiritual barrier/restriction). Rules such as not taking cooked food on hunting forays or delaying preparation of food often had to be observed. Tapu is highly regarded throughout Maori culture; a possible result of breaking Tapu on a kiwi hunt would be the loss of kiwi from that area of forest.
European settlers also hunted kiwi. Early settlers killed thousands of kiwi for their meat and feathers. Kiwi plumage was greatly desired as a ‘fur' trimming for hats and clothing. Kiwi were extensively hunted for this purpose in the mid and late 19 th Century. It soon became obvious that kiwi populations were in major decline, prompting the official protection of this species in 1896.
North Island Brown Kiwi
There are five distinct species of kiwi: Brown, Great Spotted, Little Spotted, Rowi and Tokoeka. Tokoeka consist of two subspecies.
Research into the classification of these Brown and Tokoeka Kiwi subspecies still continues.
The kiwi on display at Southern Encounter Aquarium are North Island Brown Kiwi.
Status of Kiwi in the Wild
In pre-human times (up until about 800 years ago) it is believed that around 50 million kiwi existed across New Zealand . Research indicates that kiwi numbers throughout mainland New Zealand are declining at an alarming rate of 5.8% per year. This means that the current kiwi population is halving every decade! In 2001 there were approximately 75,000 kiwi remaining. At the present rate of decline, kiwi numbers will number only 50,000 by the year 2008; many of these birds will be on protected offshore islands. The main contributing factors to the decline in kiwi numbers are loss of habitat and predation by introduced species, such as stoats, cats and dogs.In 1996 the North Island Brown Kiwi population was estimated at 35,000 birds. The projected population in 2006 is 20,000, assuming that mainland populations continue to decline at an average rate of 5.8% per year without management.
In 1900, it was estimated that the density of kiwi in the wild was up to 90 birds per square kilometre. In 2000, wild kiwi populations were estimated to be 0.45 kiwi per square kilometre.
Estimate Of Wild Kiwi Numbers (2002)
Brown Kiwi:
North Island Brown 30,000
Great Spotted Kiwi 20,000
Little Spotted Kiwi 1,260
Tokoeka:
Haast Tokoeka 250
Southern Tokoeka 25,000
Rowi 180
Territories, Burrows and Courtship
Kiwi mature when they are between 1 and 6 years old, at which time they will endeavour to find a compatible mate. Kiwi pairs form strong bonds that last for several years and sometimes for the birds' entire breeding life.
The kiwi pair will establish a territory that covers from 2 to over 100 hectares. The size of their territory will depend on the density of the kiwi population in the area and the richness of the habitat.
Each kiwi territory will contain several burrows the birds have excavated. A standard kiwi burrow is I to 3 metres long with a chamber at the end, which is large enough to house two birds. The kiwi pair will often share the same burrow.
Kiwi courtship is an unusual process. Male kiwi in captive environments have been observed to do the most extraordinary things to get the attention of a female such as jumping, hopping, flipping backwards and lying on their back kicking their legs.
What a massive egg!
Kiwi breeding biology is unlike any other bird. Both ovaries are functional in this amazing creature; each egg can take up to 60 days to form inside the female before laying occurs.
Kiwi eggs are an extraordinary size. North Island Brown Kiwi eggs can weigh 425 grams, which represents between 18 and 25 percent of the females bodyweight. This is one of the largest egg to bodyweight ratios of any bird in the world.
The egg is also incredibly energy rich. It contains 60%-65% yolk and only 35%-40% albumen (egg white); other birds eggs contain between 13% and 45% yolk. The ‘energy rich' yolk enables the embryo developing inside the egg to be sustained through the long incubation period and first week of the kiwi chick's life.
Kiwi eggs are highly desired by introduced predators mainly for their high nutrient content. Animals such as possums, rats, hedgehogs and stoats are known to prey upon kiwi eggs!
Father Kiwi does most of the incubation
Incubation routines vary throughout the different kiwi species. In both Little Spotted and Brown Kiwi, the male is responsible for incubation after the female has laid the egg. However, sometimes the female may ‘help out' from time to time. In Great Spotted Kiwi both adults take turns at incubating the egg.
Kiwi eggs hatch after 74 to 85 days of incubation. Kiwi incubate their eggs for longer than most other bird species, including other ratites (Emu & Ostrich). The length of the incubation period depends on how dedicated the parent birds have been in sitting on the egg. Kiwi have even been known to take a day off from incubating their egg!
A newly hatched Kiwi Chick enters the world
It is not easy for a kiwi chick to hatch from its egg. Kiwi do not have an ‘egg tooth' to help chip their way out of the eggshell like other birds. Instead, the chick pokes its blunt bill against the eggshell until it ‘pips' (makes a small hole), the chick then uses its strong legs to push itself out of the egg. It can take several days for the chick to completely hatch from the egg.
A kiwi chick hatches fully feathered, with its eyes open. It takes the vulnerable chick several days before it is strong enough to shuffle around the burrow. The male kiwi broods the chick during this time.
When a kiwi chick hatches it has a swollen abdomen, which contains the remaining egg yolk yet to be absorbed. This remaining food supply will sustain the chick for its first week of life.
Kiwi are at their most vulnerable when they first hatch and during the first few months of their lives, as introduced predators are able to detect young chicks very easily. The chicks are very fragile and unable to protect themselves from predators. Up to 95% of kiwi chicks fall prey to stoats and cats before they are 6 months old.
Out on their own
Although the male kiwi broods the youngster during the first week of its life, other parental obligations are very limited! Kiwi chicks soon learn to forage on their own and become independent very quickly.
By the end of the chicks first week it will have gained enough strength to venture out of the burrow with the male kiwi to forage for food. Kiwi chicks are fully independent and ready to leave their natal burrow by the time they are three weeks old.
When they are first out on their own, kiwi chicks take shelter wherever they can. They hide in small crevices and under rocks or tree trunks. Sometimes the parent kiwi may tolerate the chick in their territory for up to a year, but this is not always the case. As the chick matures it will establish a territory of its own.
Kiwi are fairly long-lived birds. Several kiwi in captivity have lived to over 20 years old and the oldest bird known was over 40 years old (and still laying eggs)
Kiwi Recovery Programme
