Kiwis are flightless birds native to New Zealand. There are five species of kiwi living today: the North Island Brown Kiwi, the Little Spotted Kiwi, the Great Spotted Kiwi, the Okarito Kiwi, and the Southern Brown Kiwi. All five species are endemic to New Zealand. Of these, the rarest kiwi species is the Rowi or Okarito Kiwi, with a population of less than 400 birds remaining in the wild.
Kiwis are unique birds and hold great cultural significance for New Zealand. Their unusual appearance and behaviors make them fascinating to study. Unfortunately, many kiwi species are endangered due to threats like predation and habitat loss. Understanding the rarest kiwi species can help focus conservation efforts on protecting these special birds.
Overview of Kiwi Species
Before exploring which kiwi species is rarest, it helps to understand some background on all five types. Here is a quick overview:
North Island Brown Kiwi
The North Island Brown Kiwi is the most widespread and common kiwi species. However, populations have declined dramatically since European settlement of New Zealand. Estimates suggest there are still around 25,000 North Island Brown Kiwis remaining. They are found throughout the North Island and on Kapiti Island off the southwest coast.
Little Spotted Kiwi
As their name suggests, Little Spotted Kiwis are the smallest kiwi species. They are identified by their grayish plumage with white spots and stripes. About 1300 Little Spotted Kiwis remain, restricted to only a few offshore islands: Kapiti, D’Urville, and Red Mercury Islands.
Great Spotted Kiwi
Slightly larger than the Little Spotted, the Great Spotted Kiwi inhabits northwest Nelson, the Paparoa Range, and some offshore islands. They have grayish brown plumage with white spots. Around 17,000 birds remain in the wild.
Southern Brown Kiwi
The Southern Brown Kiwi is found in the southwest of the South Island, Stewart Island, and some nearby islands. They have brown plumage and can grow up to 20 pounds, making them the largest kiwi species. There are still around 27,000 Southern Brown Kiwis in existence.
Okarito Kiwi
The Okarito Kiwi, also known as the Rowi, is the rarest of the five species. They are found only in a small corner of the South Island’s West Coast. With a population under 400, they are considered nationally critical.
Why is the Okarito Kiwi the Rarest?
The major reason the Okarito Kiwi is rarest is due to its extremely limited habitat. The Okarito Kiwi, as its other name Rowi indicates, lives only in the Okarito area north of Franz Josef Glacier. Their restriction to this tiny corner of native forest makes them very vulnerable.
Several factors have reduced the Okarito Kiwi’s numbers and range:
– Habitat loss from logging native forest
– Predation by dogs, stoats, cats, possums, rats, and ferrets
– Competition with imported species like deer
– Human impacts like vehicle strikes
In contrast, most other kiwi species inhabit multiple areas across New Zealand’s North and South Islands. While populations have declined, their wider distribution has prevented them from becoming as endangered as the Okarito Kiwi.
Small Founder Population
Genetic studies suggest today’s Okarito Kiwi population descended from a small founder group. Having a limited gene pool puts the species at greater extinction risk. With unpredictable environmental changes or disease outbreaks, the Okarito Kiwi lacks genetic diversity to adapt and survive.
Restricted Habitat
The Okarito Kiwi clings to survival in less than 20 square miles of temperate rainforest habitat. This remaining habitat faces degradation from introduced pests and pathogens. Their specialized forest niche means Okarito Kiwis cannot readily relocate or adapt if their fragile ecosystem suffers.
Okarito Kiwi Conservation Status and Protection
Recognizing the Okarito Kiwi’s dire situation, conservation groups have rallied to save the species from extinction. Here is a summary of protections and recovery efforts:
IUCN Red List Status
The International Union for Conservation of Nature (IUCN) Red List categorizes the Okarito Kiwi as Endangered. This means the species faces a very high risk of extinction in the wild.
New Zealand Threat Status
New Zealand’s Department of Conservation classifies the Okarito Kiwi as Nationally Critical. This is the highest threat level possible, indicating the species faces an immediate high risk of extinction.
Kiwi Recovery Plan
The national Kiwi Recovery Plan identifies the Okarito Kiwi as the highest priority species for conservation management. Millions in funding have been allocated to kiwi recovery efforts.
Predator Control
Conservation groups have intensively trapped stoats and possums in Okarito Kiwi habitat. This has helped increase chick survival. Dogs have also been banned from parts of Okarito Forest.
Captive Breeding
Several zoos and wildlife centers have established captive breeding programs for Okarito Kiwi. Offspring are raised and released to supplement wild populations.
| Year | Estimated Population |
|---|---|
| 1994 | 150 |
| 2012 | 300 |
| 2022 | 392 |
Thanks to intensive management, the wild Okarito Kiwi population has slowly increased to nearly 400 birds today. But they remain critically endangered and at risk of decline without ongoing protection.
Unique Traits and Behaviors of Kiwis
One reason kiwis are so threatened is that they evolved in isolation without mammal predators. Lacking natural defenses, they are now extremely vulnerable to introduced predators. Here are some of the unique traits and behaviors of kiwis:
Flightlessness
Kiwis are the only bird species in the world to have nostrils at the end of their long bill. Excellent scent allows them to probe the ground for food. But their reduced wings made them unable to fly away from predators.
Nocturnal Habits
Unlike most birds, kiwis are nocturnal. They spend the daylight hours hidden in burrows and emerge to forage at night. Their poor eyesight is compensated by keen smell and hearing.
Long Lifespan
Compared to other birds, kiwis are remarkably long-lived. Theyaverage 20-30 years but can survive over 50 years. Male and female kiwis form monogamous pairs and defend a large territory.
Massive Eggs
Relative to their body size, kiwis lay the largest eggs of any bird. An egg can weigh up to one quarter of the female’s body weight. Only the male incubates the eggs.
Slow Maturation
Kiwi chicks hatch fully feathered and are immediately independent. However, they take 2-5 years to reach full adult size and sexual maturity. This slow growth to breeding age hinders population recovery.
Description and Recognition
Here are some tips for identifying and distinguishing the rare Okarito Kiwi:
Size
Okarito Kiwis measure about 18 inches tall and weigh 3-3.5 lbs on average. Females tend to be slightly larger than males. They are similar in size to the Little Spotted Kiwi.
Plumage
Feathers are light brown and streaked longitudinally with a reddish hue. The tip of the bill and feet are light yellowish. Okarito Kiwis lack the white spotting of Little Spotted, Great Spotted, and young Brown Kiwi chicks.
Call
The male Okarito Kiwi’s loud, repetitive call sounds like a high whistle “kee-wee.” Females make a similar but higher-pitched “kee-wee-weet.” Calls allow pairs to stay in contact at night.
Habitat
Okarito Kiwis only inhabit coastal rainforest around Okarito village on the South Island. Nowhere else in New Zealand will you find a wild Okarito Kiwi.
| Species | Weight | Plumage | Range |
|---|---|---|---|
| Okarito Kiwi | 3-3.5 lbs | Brown streaked | Okarito only |
| Little Spotted Kiwi | 2-3 lbs | Gray with white spots | Kapiti, D’Urville Islands |
| Great Spotted Kiwi | 3.5-5 lbs | Grayish brown spotted | Northwest Nelson |
This table summarizes some key traits to identify and compare the three rarest kiwi species. The Okarito Kiwi’s small isolated range makes it stand out.
Threats and Challenges to Kiwi Survival
Why are all kiwi species facing population declines, with some endangered? Here are the main threats these unusual flightless birds confront:
Habitat Loss
Since humans arrived in New Zealand, over 90% of native forests have been cleared for timber and farming. This destroys the dark, secluded forests kiwis rely on. Some species now cling to survival on offshore islands where habitat remains.
Invasive Predators
Stoats, ferrets, cats, rats, possums, and feral dogs prey heavily on adult kiwis, eggs, and chicks. Kiwis lack adequate defenses against these introduced mammals. Predation is the primary cause of mortality.
Competition with Invasive Species
Introduced deer, pigs, and wallabies degrade and compete with kiwis for resources. Invasive weeds also displace native plants kiwis need.
Vehicle Strikes and Human Disturbance
Kiwis face vehicle collisions in areas near roads. Human activities like trampling burrows, dog attacks, and lighting fires also threaten kiwi survival.
Climate Change
Rising temperatures and increased storms may degrade or alter forest habitats. Kiwis are adapted to historic stable conditions. Climate shifts could exceed their ability to adapt.
Efforts to Save Kiwis
Many public and private efforts aim to protect kiwis from extinction. Some key conservation initiatives include:
Predator Control
Setting traps, using poison baits, and creating predator-proof enclosures protect vulnerable kiwi populations from invasive mammals. For example, massive predator control enables kiwis to thrive on offshore sanctuary islands.
Habitat Restoration
Conservation groups replant native vegetation and remove invasive plants. This helps recreate dark, secluded forests suited to kiwis. Fencing also protects regenerated habitat from deer and livestock.
Captive Breeding
Breeding programs at wildlife centers and zoos boost numbers of rarer kiwi species. The chicks are raised until large enough for release into the wild.
Public Awareness
New Zealanders have rallied around saving their iconic kiwis. Events like Kiwi Day educate people. Dog owners are encouraged to restrain pets to protect neighborhood kiwis.
Species Recovery Groups
Each kiwi species has a dedicated recovery group that oversees scientific management, monitoring, and community engagement for that species. The groups coordinate with government agencies, scientists, conservationists, land owners, indigenous Maori groups, and the public.
Outlook for Kiwi Conservation
Targeted efforts have slowed declines and even increased some kiwi populations. But all species remain at risk without ongoing management. The future outlook depends on:
Sustained Funding
Saving kiwis is expensive work. Predator control, habitat restoration, breeding programs, and other efforts require significant long-term funding to succeed. Government and public support is essential.
Ongoing Predator Control
If control of invasive mammals lapses, kiwi populations will crash as predation skyrockets. Kiwis have no innate defenses against the many introduced predators.
Habitat Protection
Preserving remaining old growth native forests is crucial for kiwi strongholds. Regrowth forest takes decades to suit kiwi needs. Climate policies that maintain wet forest ecosystems will also help habitat.
Public Engagement
Locals must support neighborhood kiwi protection programs. For example, restraining dogs, driving carefully at night, and reporting kiwi sightings. Community stewardship is vital.
Climate Resilience
Kiwis evolved for a different climate. Scientists must identify populations most at risk from climate change and possibly translocate them to more resilient habitats.
Conclusion
Of the five kiwi species, the rarest is the Okarito Kiwi. Fewer than 400 of these unique birds cling to survival in a remote corner of the South Island. Ongoing intensive management and public support offer hope of bringing the Okarito Kiwi back from the brink. The specialized behaviors and vulnerabilities of kiwis highlight the fragility of New Zealand’s distinctive native wildlife. Targeted conservation efforts can successfully recover endangered species when acted on in time. But preventing declines in the first place through habitat protection is always preferable. The flightless kiwi serves as an important symbol of New Zealand national identity and a reminder of people’s responsibility to guard these islands’ natural heritage.
