Kiwi Behavior

Kiwis are territorial and some under the right conditions will come crashing through the undergrowth, head held high with bill pointed upwards to defend their territory. Both male and female kiwis make a variety of sounds, most notably a characteristic whistle sound, that is believed to serve two purposes—to define their territory and preserve the connection between mating pairs. Kiwi most commonly call shortly after emerging from their burrows at night.

The male’s call is a very loud prolonged shrill ascending and descending whistle call; the female’s call is a bit more guttural. Kiwi also make a sort of snorting, snuffling sound as they blow the soil out of their nostrils after probing the soil with their bill.

They usually have a number of burrows throughout their territory which they dig or expand themselves, usually under fallen trees, under the roots of large trees or in hollow trees. Burrows can be up to 2 meters long.

Once bonded, kiwis tend to generally live their entire life as a monogamous couple (10-30 years).

Some species lay one egg each year, other species lay two clutches each year with up to two eggs in each clutch. Kiwi have particularly large eggs for their body size, one of the largest egg-to-body weight ratios of any bird. For the kiwi, the egg averages 15% of the female’s body weight.

An egg for the great spotted kiwi, for example are about 5 inches long and weigh almost one pound).

The incubation period is 65-85 days which is long for birds. Most birds have incubation periods of about 20 days. Even a huge bird such as an ostrich has an incubation period of only 44 days. Two of the five species of kiwi have role reversal—the male incubates the egg or as they might say here in New Zealand “dads behave as mums”.

The kiwi egg has lots of yolk compared to other bird eggs. One brown kiwi egg is equivalent in nutritional value to a dozen hen’s eggs. When the chicks are hatched, they have adult plumage and are generally fully-developed. The parents don’t feed them, rather the large yolk sac provides them with food for up to a week. After hatching kiwi leave the burrow in about a week and afer only ten days some are already staying out all night!

Again, most people never see a kiwi in the wild and if they are do, it is often a momentary glimpse of one waddling into the undergrowth. A number of places exist in New Zealand where you can go to attempt to see a kiwi in the wild. We went to one, Trounson Kauri Park north of Auckland. The owner of the nearby holiday park (campground) was very knowledgeable and gives guided night tours. But on our day there, the weather was bad (wind and rain) and the tour was cancelled. He said that quiet nights are best and you can often hear the kiwi walking through the underbrush. Also there is very real danger of epiphytes (large plants that grow perched on tree branches) falling out of the trees in windy weather and killing you. In that particular forest, he said there were about 100 kiwi. His success rate at seeing one on any given night was about 50%.

Despite the weather, we went out on our own that night and spent several hours listening and carefully probing the forest with our flashlights (red light is best, we had white). The forest (bush) was a strange, magical world at night, but we neither saw nor heard any kiwi.

The Kiwi in Decline

Kiwi numbers have been in decline for many years and unfortunately the decline continues.

One estimate gives the peak kiwi population in the past at 12 million; now around 70,000 are left. And even now the Department of Conservation estimates that 2% of the kiwi population is still being lost each year.

The causes of the kiwi decline after the arrival of man were listed above. Interestingly, there were rare voices even in the 1800’s warning of the danger to the kiwi population. As early as 1871, Thomas Henry Potts, a Canterbury naturalist, argued for the protection and preservation of the kiwi during a time when thousands were being slaughtered for their skins to make muffs and trimmings for garments in Europe.

In the late 1890’s, Resolution Island in Fiordland was designated as a nature sanctuary and a place where birds could be safe in a predator-free environment. The custodian, Richard Henry, (on whom I plan to do an separate post) transferred over 750 birds (kiwi, kakapo and weka) to Resolution Island and nearby islands over a number of years. Unfortunately, in 1900 a stoat or weasel made its way to Resolution Island and Henry left with the knowledge that all his work was for naught.

In 1896 the New Zealand government accorded the kiwi full legal protection. Despite its protected status, significant declines continued to occur in the twentieth century. For example, brown kiwi numbers on the North Island plummeted by 90% during that time.

It was only in the 1990’s that it was fully recognized that the kiwi would soon be extinct, and it was decided something had to be done about it. A pivotal research paper in 1996 established that the biggest threat to chicks and juvenile kiwi were mainly stoats, and that the biggest threat to adult kiwis was dogs. After reaching a certain size and weight, it was felt that kiwis could generally defend themselves against stoats. Other mustelids (ferrets and weasels) along with feral cats (cats or kittens dropped off in remote areas) also played a role.

Along with this, habitat loss continued to be a pressing problem.

Based on this, a multi-pronged plan was instituted: the establishment and maintenance of island and mainland sanctuaries where kiwis would be protected from predators, and the removal of kiwi eggs and chicks from nests and allowing them to hatch or to grow in a protected environment until reaching a size (800-1200 g) where they could defend themselves in the wild. At this time it was estimated that only 6% of mainland kiwi eggs survived to adulthood. A goal of 20% survival rate was established.

Operation Nest Egg was started in 1996 to do this. One interesting aspect of this was the use of “smart eggs”—fake eggs packed with electronics that an adult kiwi would be allowed to incubate. The sensitive electronics would faithfully record the temperature and turning frequency, etc. so that similar conditions could be reproduced in the hatchery. In time the program began to show success.

In 2000 five major land sanctuaries were established for kiwi by the government with extensive predator control and monitoring of a representative number of kiwi by radio-tagged collars.

Along with this in recent years, upwards of 70 community based conservation projects in diverse areas have also been established. One positive effect of these programs is that it brings more awareness to people on a local level, including the devastating effect dogs can have on kiwi. For example, one dog over a period of time was found to have killed over 500 kiwi.

Despite these programs, all kiwi are still threatened with extinction to varying degrees. The rowi and tokoeka are most threatened. The brown kiwi and the great spotted kiwi are “nationally vulnerable”, and the little spotted kiwi is “at risk”.

Estimates of kwi numbers and status as of 2011 were as follows:

Brown kiwi – 25,000 birds but in serious decline.

Haast tokoeka (South Island brown kiwi) – tokoeka sub species, population of 350, “nationally critical”.

Fiordland tokoeka – tokoeka subspecies, 14,500, in gradual decline.

Stewart Island tokoeka – tokoeka subspecies,15,000, in decline.

Rowi – 350, critical.

Little spotted kiwi – 1500.

Great spotted kiwi – 13,000, gradual decline.

The Kiwi as a New Zealand Icon

You see the kiwi all over. It’s on coins, stamps, business logos and tourist memorablia. The kiwi you commonly see is a version of the North Island brown kiwi, the quintessential kiwi.

For a while in its early years, the moa, another flightles bird, vied with the kiwi for status as a national symbol. But perhaps because the moa was extinct, the kiwi won out.

New Zealanders are also called Kiwis (capital ‘K’). The name originated during World War I when New Zealanders fought in Europe. The New Zealand dollar in foreign exchange markets is called the kiwi. Kiwiana refers to things distinctively Kiwi or New Zealand such as pavlova, gumboots and No. 8 wire (alledgedly a true Kiwi can make or repair most anything using just No. 8 wire).

However, the fruit sometimes called a kiwi is more accurately called a kiwifruit. Its true name is Chinese Gooseberry but after it was begun to be grown in New Zealand, the name was changed to avoid any connection with China and perhaps to make it sound more appealing.

Oh, how about Kiwi brand shoe polish? That was originally an Australian company. The brand is now owned by S.C. Johnson, a privately-held US company.

References:

Castro, Isabel (2011). Kiwi A natural history.

Peat, Neville (2006). Kiwi The people’s bird.

Fuller, Errol (ed) (1990). Kiwis.