A third Kiwi chick hatched at the Columbus Zoo and Aquarium on Jul. 17, marking the first time an institution in North America has successfully hatched three kiwi in one year. The Columbus Zoo’s first hatching of the North Island brown kiwi (Apteryx mantelli) occurred less than four months ago on March 23, while the second hatched on June 25, 2011.
This newest little chick, a female, is currently being cared for behind-the-scenes. The first two chicks are both males and have been given names reflecting their native New Zealand; “Ariki” (ah-ree-kee), meaning first-born or chie,f and “Toa” (to-ah) meaning warrior. The oldest of the chicks, Ariki, can be seen in the Zoo’s Roadhouse nocturnal habitat for a few hours each day.
Only seven kiwis, including the three at the Columbus Zoo, have hatched in the past five years in North America. The Columbus Zoo is only the third zoo in North America to successfully hatch a kiwi chick since the first one hatched at Smithsonian’s National Zoo in 1975. There are now six kiwis at the Columbus Zoo and Aquarium and a total of 22 kiwis in three United States zoos.
The Columbus Zoo’s conservation program has supported projects to protect the kiwi including supplying funds to construct predator proof fencing around reserves and fitting kiwis with transmitters to enable regular monitoring.
Kiwis are flightless birds about the size of a domestic chicken and the egg, weighing as much as 20% of the female’s body weight, is the largest egg in relation to body size of any bird. The female kiwi lays one egg at a time in the burrow occupied by the male kiwi. In the wild the male completes the average 86-day incubation process on his own.
At the Zoo eggs are checked to see if they are fertile 30-45 days after they are laid. To maximize the potential of a successful hatching a fertile egg is placed in an incubator where it is monitored for temperature and humidity and turned slightly each day. Once the chick pips the egg it takes about four days for it to completely emerge and it survives on its yolk sac for 6-12 days.
Kiwi chicks are miniature versions of the adult kiwi and are about 1/8 of the size of an adult when they hatch. They are precocial, meaning they are completely on their own after hatching, and must find food and avoid predators without assistance. Most birds locate their food through sight and have a relatively poor sense of smell. Being nocturnal, the kiwi’s senses are just theopposite and they use their long beak to forage through leaf litter sniffing out earthworms and other invertebrates, fruits and berries.
Kiwis have a high mortality rate in the wild mostly due to predation by invasive species; 50% of kiwi eggs fail to hatch, 90% of chicks do not survive to six months of age and only 5% reach adulthood. Kiwi males are sexually mature at two years of age and females are reproductive at about three years old.
The five distinct species of kiwi are only found in New Zealand and in zoos outside of New Zealand.