Friday, December 5, 2014

Save the Kiwis!

Apteryx australis
Photo cred: Wikimedia

 Kingdom: Animalia 
Phylum: Chordata 
Class: Aves 
Order: Apterygiformes 
Family: Apterygidae 

Although many of you probably thought of the fruit first, this research focuses on a bird native to New Zealand- the Southern Brown Kiwi Bird, or Apteryx australis. You may see the name and think “Australia”, but the name actually means “without wings” and “relating to the south wind”.(8) They are what is to be considered a ratite. 

Range and Habitat 
The Southern Brown Kiwi Bird is found in the south island of New Zealand. More specifically, it can be seen in Fiordland and Westland. It can also been found on Stewart Island- an island off the coast of the Southern Island of New Zealand.(1) They can be seen in temperate, sub-tropical forests, as well as grasslands and shrubbery. In some occasions, you can also find them in sand dunes. One of the most important factors for the Southern Brown Kiwi is to live in a place that is large, dense, and dark. This helps them to camouflage into their surroundings during the day and be unseen by predators while they sleep. Southern Brown Kiwis tend to create burrows under stones that are present in their environment, or even in banks of streams, or in soft, flat, open ground.(4)

Physical Description
Kiwi birds have an odd shape to them; they have a round body with a head attached to it, and they also have no tail- they only have some caudal vertebrae. The kiwi’s wings are reduced in size, which explains why they can’t fly. Their feathers have no aftershafts or barbules. Kiwis also don’t have a preen gland (a gland that produces oil).(8) They also have muscular legs, which aid their terrestrial kind of lifestyle. (6) One of the key features that distinguish kiwis from other small birds is their beak; they are long and slender with a slight curve, although some species of Kiwi may have straight beaks. Nostrils can be seen at the tips. Kiwis are known to have an advanced sense of smell and hearing. (6) Their color is reddish/brown with some streaking. The length of the birds range from 18-22 inches, the females weigh between 4.6 and 8.6 pounds, and the males eight 3.5 to 6.2 pounds. (7) 

Evolutionary History 

Photo Cred: Kiwis for kiwi

According to a charity group called The Kiwi Trust (5), they state that what is known to be the “proto-kiwi”- an ancestor of the Kiwi Bird- arrived in New Zealand about 50 million years ago. They say that the oldest fossil of the Kiwi that has been found was a femur located on the North Island that dated back to 1 million years ago. TKT explains that the main influence on Kiwi evolution was the ever-changing landscape and formation of New Zealand over the years. There are three basic islands to New Zealand- the north island, the south island, and Stewart Island; they were all joined at one point, eventually split which changed their overall shapes. The Kiwi Trust further explains that when these changes happened, the Kiwis were separated and isolated from each other. As described before, since they can’t fly, there were no ways for the Kiwis to find their way back to each other, which meant that they were forced to stay where they were and breed among the kiwis that were around them. By understanding the mechanisms of natural selection, this essentially led to the differentiations that we see among the different species of kiwis. 
In a New York Times article written by Malcom W. Browne in 1992(2), he talks about how the Kiwis are more closely related to Ostriches than Moas, which was the previous thought. A group of scientists amplified DNA fragments from species of flightless birds thought to be like the Kiwi, and they found that the gene structure of the Moa is a lot different than birds like the emu and ostrich. Because of this, the scientists question if the Kiwis descended from an ancestor that lived in Australia. It would make sense, especially if the two species were separated from each other during land mass splits. 

Kiwis often make distinct vocalizations in order to defend their territories. They usually make these calls in an upright position with their legs stretched and their beaks facing upwards. The males and females also sing duets with each other; the males make a “kee wee” or a “kee kee” sound, while the females make more of a “kurr kurr” sound. (7) Kiwis are quite shy and usually spend time alone, but they can also be seen traveling in companies usually between 6 and 12 kiwis. (4) As for the Kiwi’s diet, they eat insects, crayfish, amphibians, eels, and fruits. The nostrils on their bills gift them with a great sense of smell. Smell is actually their primary sense that they use- even over sight and sound. Their talented sense of smell helps them to find their prey that may be located in the ground. When they catch their prey, they proceed to beat it against a rock or the ground until the prey is dead- then they consume it. (1) When it comes to reproduction, the Kiwi is a monogamous species. Rituals for mating begin in March and last through June, where the Kiwis meet each other in burrows to mate. (4) Females usually lay one egg, but sometimes they lay 2, and the males incubate the egg(s) for almost 90 days, and then the chicks leave the nest after a few days and fend for themselves. (1) Female Kiwi birds reach sexual maturity between 3 and 5 years old, while the males reach sexual maturity at 18 months. (4) 
  • Interesting Fact: One unique thing about Kiwis is that they lay huge eggs compared to their body size. According to the WWF (6), they say that the eggs are about 20% of the Kiwi’s body weight, making it proportionally one of the largest of most birds. In a study done by William A. Calder III and other scientists(3), they have backed the finding that Kiwis produce one of the largest eggs compared to their body size among most birds. The scientists studied the energy content of the Brown Kiwi’s eggs; they say that a group of organisms called the megapods have the “largest proportionate yolk know, 62% of egg contents”. The Kiwi bird egg that they looked at had a value of 61.1%- a very close value. 

Conservation Status
In 2000, the IUCN stated that the Southern Brown Kiwi Bird was in “vulnerable” status; Fiordland had only a population of 7,000. (4) The common predators to the Kiwi bird are possums, stoats, and cats- they tend to eat the Kiwi’s eggs and/or juveniles. Adults are usually eaten or attacked by dogs, ferrets, and possums. (8) Kiwi birds have been hunted to make cloaks, and have even been eaten by humans, which both only declined the population. The New Zealand government has gone to the extent to declare that if there is ever a flu that attacks the birds of the country, every Kiwi bird will be vaccinated to prevent any more of a decline in their population. (4) Another conservation effort included the Kiwi Recovery Program set by the Bank of New Zealand in 1991. This program offered predator control, kiwi sanctuaries, outreach and education, as well as a captive breeding program called Operation Nest Egg which started in 1995. (9) Other efforts include translocations of Kiwis as well as legislation to keep dogs- a predator of the Kiwi- under stricter control. In order to keep track of the population, Kiwis have been banded and radio-tracked; Kiwi eggs have also been removed from nests by humans and incubated, and then they were returned as young adults when they were old enough to fend for itself. (7) WWF New Zealand has also created conservation efforts that help to protect the Kiwi population. They have also taken part in translocation efforts, breeding grounds, and predator control like the other conservation efforts have been trying. 

(1) "Brown Kiwi (Apteryx Australis)." Encyclopedia of Life. Web. 13 Nov. 2014. <>. 

(2) Browne, Malcolm W. "Extinct Bird and Kiwi." The New York Times. The New York Times, 21 Sept. 1992. Web. 13 Nov. 2014. <>.

(3) Calder, William A., C.r Parr, and D.p Karl. "Energy Content of Eggs of the Brown Kiwi Apteryx Australis; an Extreme in Avian Evolution." Comparative Biochemistry and Physiology Part A: Physiology 60.2 (1978): 177-79. Web. 

(4) Gudipati, Smitha. "Apteryx Australis." Animal Diversity Web. University of Michigan Museum of Zoology, n.d. Web. 13 Nov. 2014. <>

(5) "How Kiwi Evolved." Kiwis for Kiwi. BNZ, n.d. Web. 13 Nov. 2014. <>.

(6) "Kiwi." WWF New Zealand. WWF, n.d. Web. 13 Nov. 2014. <>.

(7) Robertson, H., and B. Weeber. "Southern Brown Kiwi Apteryx Australis." BirdLife International. BirdLife International, n.d. Web. 13 Nov. 2014. <>.

(8) "Southern Brown Kiwi." Wikipedia. Wikimedia Foundation, 11 Dec. 2014. Web. 13 Nov. 2014. <>.

(9) "Tokoeka (Apteryx Australis)." ARKive. N.p., n.d. Web. 13 Nov. 2014. <>.


  1. There are five species of kiwi birds all of which are native to New Zealand. They are also the national symbol for new Zealand. Here in his article, I will present Kiwi Bird Images Facts and its classification with photos.