Kiwis are endangered because of the presence of stoats and dogs. Stoats, members of the weasel family, are responsible for half of kiwi chicks' deaths.
Rats also play a role in the diminished number of kiwis. Because they compete for food with the kiwi, they become food for stoats. As a result, the presence of rats means there is a higher number of stoats. Without human intervention, only 10 percent of kiwi chicks survive to six months. Kiwi chicks remain vulnerable to stoats until they reach about 2 pounds when they can usually defend themselves.
Dogs frequently kill adult kiwi, causing major declines in local populations. All breeds of dogs, regardless of size or training, can kill kiwis; dogs are attracted to kiwis due to the birds' distinctive scent. Kiwis are easily crushed in dogs' jaw because the kiwis have no breastbone. The life expectancy of the adult Northland brown kiwi is 14 years on average because of dog attacks.
Cats, when uncontrolled, wild or abandoned, also attack and kill kiwi chicks. Ferrets frequently kill adult kiwi, and mammals introduced to an area can also have an impact on kiwi. Competition by these animals for similar food results in delayed growth of kiwi chicks.
The New Zealand government has earmarked an additional $6 million for research to control stoats. More than 80 community groups have been formed to protect the kiwi. The New Zealand Department of Conservation has set aside a 240-square-mile area for public conservation of the kiwi.