Rowi Kiwi

## About

A rowi kiwi on Mana Island

The rowi kiwi ***(Apteryx rowi)*** sometimes referred to as the rowi, is the rarest of the five kiwi species and is native to the rainforests of South Island, New Zealand. The rowi is similar in appearance to other kiwi species, having long brown feathers, a round body, long tan bills and small eyes, which are all attributes found in other kiwi species. The feathers of the rowi are loose and soft, resembling fur to the touch more that the typical feathers. Rowi also have long modified feathers at the base of their bills which are thin and wispy. the exact use of these feathers are unknown however, it is hypothesised that they are an evolutionary parallel of mammal whiskers, and are used to help kiwi species navigate at night, as they are strictly nocturnal birds. Though ultimately similar to other kiwi species, rowi have more greyish plumage, and their whiskers and facial feathers may also appear silver or white in colour. Rowi move with a bobbing motion and are incredibly fast, apparently matching the speed of most people, despite their stubby legs. Interestingly, the body temperature of a kiwi is much closer to that of a mammal than a bird, ranging from 37-38ºC (98.6-100.4ºF) as opposed to the typical 39-42ºC (102.2-107.6ºF). These mammal-like features suggest that kiwis and rowi convergently evolved alongside rodents, mimicking their attributes and filling their niche on New Zealand. Rowi measure to be up to 40cm (15.74in) in length from bill to rump and differ in weight between sexes, with males weighing 1.9kg (4.11lbs) and females weighing 1.2kg (2.64lbs). With these measurements, rowi are one of the larger kiwi species.

## Diet

As carnivores, rowi consume a large variety of meat matter, species such as earthworms, beetle larvae, moths, cicadas, spiders, crickets and many other insect species. Rowi are opportunistic, also eating freshwater crayfish. Rowi may even be omnivorous, possibly eating leaves and fallen fruits if necessary. Rowi hunt at night and will use their combined senses of their whiskers and their bills to hunt, tapping their bills on the ground whilst slowly walking and probing their bill in front of them in order to catch potential prey.

## Conservation Status

Mass historic decline can be attributed to the small rowi population of the modern day. The introduction of invasive species to New Zealand during its European discovery contributed to a mass population loss for not only rowi, but most of New Zealand's fauna. Species such as dogs and cats brought for companionship and pest control respectively, contributed greatly to the decline of the rowi through hunting of adults and juveniles however, rats were much more threatening to the population, quickly consuming eggs and directly competing with the rowi and other kiwis for the niche of a nocturnal scavenger. By far the most threatening invasive species to rowi presently is the ermine or stoat ***(Mustela ermina)***, which was originally introduced to cull the rabbit population, continued to prey upon the eggs and young of the rowi up until the 1990s. Adult rowi may also become victims of roadkill, as they often have to cross man-made barriers like roads, at night. Due to the strain applied to the population through the introduction of invasive species, rowi were eliminated completely from their historical range in the North island, as well as their range in the Northernmost points of the South Island however, since European contact, the rowi has only been known from areas of Ōkārito, giving it the alternative name of the Ōkārito brown kiwi. During 1995 the rowi population dropped to an all time low of 160 individuals as a result of stoat predation. This population has actually grown since then thanks to a breeding program known as 'Operation Nest Egg'. Operation Nest Egg's main objective was to increase the rowi population through the hand rearing of chicks. Eggs and juveniles were collected from the wild and raised in captivity, to be eventually released onto predator-free islands. The efforts of Nest Egg allowed the rowi population to rebound to a total of 200 individuals by the year 2000, and during the years following the operation would be instated once again in order to combat stoat predation. Operation Nest Egg would prove to be a conservation success story, with populations being estimated at 375 individuals by 2012. Because of Operation Nest Egg, the species is no longer considered endangered, instead being vulnerable by the IUCN.

## Range and Population

Rowi once inhabited areas of as far North as Lake Poukawa in New Zealand's north island, as well as areas across the west coast of the South Island. Today, rowi only occur in the Ōkārito area in Westland of the South Island. Rowi presently inhabit lowland forests and rainforests in Ōkārito and have also been introduced to islands such as Montuara and Mana island. These islands are free of predators and have been proven to help increase the population, with individuals already establishing breeding on Mana island as of 2016. In wake of Operation Nest Egg, the rowi population has rebounded from 160 individuals to a much more stable 350-400 mature individuals as of 2020 and it continues to increase. A new problem has arrived for rowi population however, in that island populations may possibly grow to large for the islands, as adult rowi require large territories that do not overlap. A similar problem has become apparent for the South Island takahē ***(Porphyrio hochstetteri)***, another New Zealand bird, which has been a part of similar conservation efforts.

## Behaviour

Rowi are solitary birds that are extremely territorial, individual territories do not overlap, and encounters with each other outside of mating season typically result in fights. Despite their territorial nature, rowi will share their territory with a mate, often calling to them throughout the night. Rowi pairs may also duet, calling one after each other in order to maintain contact. Like all kiwi species, rowi are also nocturnal, favouring to stay out of the sun and in their burrows until nightfall. These burrows can be made in a variety of locations, from a deep underground nest to the base of a tree hollow. After a breeding season lasting from July-March, a rowi female will lay an egg that weigh approximately 15% of her bodyweight during the months of July-January. The rowi pair will practice monogamy and incubate the egg in a shared burrow, alternating incubation of the egg. The egg will eventually hatch after an incubation period of 70-80 days. Rowi chicks emerge from the egg fully-feathered and capable of sight, eventually gaining full independence from its parents at around 14 days old. Once a rowi reaches 4 years old, it will be sexually mature and ready to mate. Rowi may live up to 34-48 years. Interestingly, evidence shows that rowi may breed with little spotted kiwis ***(Apteryx owenii)*** as suspected hybrids have been found. This may pose a problem for the rowi population, as the hybrids have been found to be fertile, as two individuals successfully reproduced. A hybridised subpopulation of the two species has a potential to cause genetic instability in the rowi, possibly to the point of replacing the species with hybrids. Luckily, little evidence of hybridisation has been found, and the rowi population remains genetically pure.

### Relationship with Humans

Rowi are very skittish birds, pairing this with their nocturnal lifestyle makes it difficult for rowi to be captured or even sighted by humans at all. If confronted rowi will not attack humans, typically remaining frozen after escaping to their burrows. If a rowi is incubating an egg, the bird will rarely retaliate against human egg retrievers, usually staying still as to avoid conflict. Due to the flighty nature of rowi and their inability to defend their nests from humans, members of Operation Nest Egg can typically retrieve eggs for captive breeding with limited strain.

## In Captivity

Rowi are not kept in captivity often, only being in institutes owned by Operation Nest Egg however, Nest Egg has also worked cooperatively with Auckland Zoo in order to retrieve eggs from Ōkārito and other areas of the West coast. Despite the collaboration with Auckland Zoo, no rowi exist in publicly accessible facilities like zoos.

## Sources

* IUCN Redlist of Threatened Species - https://www.iucnredlist.org/species/22732871/180757495
* Ōkārito Brown Kiwi | New Zealand Birds Online - https://nzbirdsonline.org.nz/species/okarito-brown-kiwi
* Rowi | New Zealand Department of Conservation - https://www.doc.govt.nz/nature/native-animals/birds/birds-a-z/kiwi/rowi/
* Kiwi Facts | Rainbow Springs Nature Park - https://www.rainbowsprings.co.nz/kiwi-conservation/kiwi-facts/
* Honorary Mammals | Kiwi Ora, Save The Kiwis - https://www.savethekiwi.nz/about-kiwi/kiwi-facts/honorary-mammals/
* Is the Genetic Integrity of the World’s Rarest Kiwi at Risk From Hybridisation? | Museum of New Zealand - https://blog.tepapa.govt.nz/2021/06/09/is-the-genetic-integrity-of-the-worlds-rarest-kiwi-at-risk-from-hybridisation/?cn-reloaded=1
* Five Surprising Kiwi Facts | 100% Pure New Zealand - https://www.newzealand.com/nz/feature/five-surprising-kiwi-facts/#
* Operation Nest Egg With Keeper Nat | Auckland Zoo - https://www.youtube.com/watch?v=htLf4hqGqSw