Apteryx
By Snowmanradio, CC BY 2.0
Name: Apteryx
Status: Extant
First Described: 1813
Described By: Shaw
Classification: Dinosauria, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoriformes, Maniraptora, Pennaraptora, Paraves, Eumaniraptora, Averaptora, Avialae, Euavialae, Avebrevicauda, Pygostylia, Ornithothoraces, Euornithes, Ornithuromorpha, Ornithurae, Neornithes, Palaeognathae, Notopalaeognathae, Novaeratitae, Apterygiformes + Aepyornithihformes Clade, Apterygiformes, Apterygidae
Referred Species: A. haastii (Great Spotted Kiwi), A. owenii (Little Spotted Kiwi), A. rowi (Okarito Brown Kiwi), A. australis (Southern Brown Kiwi), A. mantelli (North Island Brown Kiwi)
Here we are - the smol ratite, the Kiwi! Kiwi are flightless birds from New Zealand the size of a chicken, and even though they are the smallest ratites known, they actually have the largest egg in relation to their body size of any bird:
By Shyamal, CC BY 3.0
Kiwi look on the appearance as if they have no wings (much like the Moa, another kind of ratite from New Zealand), however underneath their shaggy feathers they do have vesitigial wings and tiny wing claws. They don’t have a keel or sternum to anchor wing muscles, so they are definitely on the evolutionary path towards losing all their adaptations for flight muscles, and they also don’t have a preen gland. They have the smallest eyes relative to body size for any bird which gives them the smallest field of vision for a bird, and blind Kiwi have demonstrated that these birds don’t really rely on vision to investigate their environment. They also have very big brains, similar to those of parrots and songbirds in terms of size compare to their bodies. This genus first appeared sometime in the Quaternary, around 0.012 million years ago, though fossil records of this bird of are poor. The five species range all over New Zealand:
By Tony Wills & Grutness, in the Public Domain
However, despite this wide range, all five known species are endangered to some degree, with many in serious risk of extinction due to human activity in New Zealand (and, of course, the greatest evil, outdoor cats). There are extensive conservation programs to protect Kiwi, including sanctuaries, breeding programs, and habitat preservation. They are one of the national symbols of New Zealand and are considered to be under the protection of gods by the Māori, and the Māori gave us the name for the bird - Kiwi! All Kiwi are nocturnal birds today, but that might actually be a new behavior evolved to avoid invading mammal predators - because when they feel safe, they are often seen during the day. They have very good senses of smell, and their nostrils are at the ends of their beaks - allowing them to smell out food and grab it with their long beaks. They eat invertebrates, seeds, grubs, and lots of worms, as well as fruit and other small animals. They can find invertebrates underground using their sense of smell. They monogamously mate for life, and live together in nesting burrows, and they actually have a pair of ovaries - rather than a single ovary as found in other birds. They lay one egg per season, which are incubated mostly by the males for 63 to 92 days. In the thirty days it takes for the egg to be developed by the female, she has to eat three times her normal amount of food, and then fasts when the egg is too big for her to actually have a full stomach.
Great Spotted Kiwi, in the Public Domain
Our first species is the Great Spotted Kiwi, which lives primarily in the South Island, and it is the largest species of Kiwi. It lives in a variety of harsh climates that are inhospitable to invading mammals and, as such, it isn’t as under threat from predators as other Kiwi as, but they are vulnerable to habitat destruction. It is very aggressive and has large territories - up to 49 acres - that they defend against other Kiwi. They mainly sleep during the day in burrows. The males are about 45 centimeters long, while the females are up to 50 centimeters long. They have short legs and essentially nonexistant tales, making them look like fun little round balls with long beaks coming out of them. They have black spots on their feathers. They live in high altitudes and move around from burrow to burrow every day. They are also able to fend off predators due to their large size.
Little Spotted Kiwi, in the Public Domain
The Little Spotted Kiwi, on the other hand, are the smallest species of Kiwi - only about 35 to 45 centimeters long, with the females a little heavier than the males. They live on islands off the coast of New Zealand in multiple spots, where they are protected through Kiwi sanctuaries, where a lack of predators is allowing its numbers to increase. They nest in burrows, and feed on small insects from underground. They mainly live in forested habitats, though some can be found in scrubland.
Okarito Kiwi by Pseudopanax, in the Public Domain
The Okarito Kiwi is a newly described species of Kiwi that lives in one location - the Okarito Forest on the west coast of New Zealand’s South Island. The females of this species actually can lay up to three eggs in one batch, each in a different nest, and both parents work together to incubate the eggs. Due to habitat loss and predation, they’re vulnerable to extinction, especially thanks to introduced stoats. Conservation programs are in place to help this species, and breeding programs are ongoing.
Southern Brown Kiwi by Glen Fergus, CC BY-SA 2.5
The Southern Brown Kiwi is exclusively found on New Zealand’s South Island, and it is moderate in size, usually about 45 or so centimeters in length. The males are more vocal, making calls that sound like “kee-wee” or “kee-kee”, and the females respond with “kurr-kurr”. They have territories between 12 and 106 acres, and they make nests out of burrows where the females lay between 1 and 2 eggs that are incubated by the males for 90 days. They are vulnerable, due to threats from introduced mammal predators, and populations on certain smaller islands are protected.
North island Brown Kiwi, in the Public Domain
The North Island Brown Kiwi is the most common Kiwi - and yet, it is vulnerable to extinction. It is the bird with the largest eggs relative to its body, and it lives entirely in New Zealand’s North Island. They’re also the only Kiwi found in zoos. They’re slightly smaller than the South Island Brown Kiwi. They have two eggs in each clutch, with two to three clutches a year, and the chicks are able to fend for themselves within a week of hatching. Breeding programs are in place to attempt to maintain the population, though throughout New Zealand it is decreasing at a rate of 2% per year.
Sources:
https://en.wikipedia.org/wiki/Kiwi
https://en.wikipedia.org/wiki/Great_spotted_kiwi
https://en.wikipedia.org/wiki/Little_spotted_kiwi
https://en.wikipedia.org/wiki/Okarito_kiwi
https://en.wikipedia.org/wiki/Southern_brown_kiwi
