Not all species of kiwi are endangered, but they are all certainly under threat. The biggest threat to the kiwi comes from dogs, feral cats and other imported pets including the stoat, of all things, as well as ferrets. New Zealand has no native predators. Being a small, flightless bird, the kiwis defenses are extremely limited. Many kiwis are also killed every year by unregistered Pig-Hunting dogs (registration requires Kiwi Aversion training) and being killed while crossing roads/highways.
Loss of habitat due to deforestation and destruction of large tracts of native bush is also endangering the kiwi. Not only does this threaten its food sources, but deforestation means the kiwi has fewer places to hide from its many predators. Prior to Europeans coming to New Zealand, the kiwi enjoyed a healthy population.