New Zealand has four species of rodent: kiore, Norway rat, ship rat and the house mouse. All were introduced. Kiore are regarded as a valued taonga by some iwi.
Rats and mice are usually in the bush in large numbers. They pose two problems for kiwi. First, they degrade native forests by eating the fruit that native birds depend on for food and the forest needs for natural regeneration. Second, they are food for the kiwi’s predators – mustelids and cats – and help keep the populations of those lethal predators high.
Hedgehogs are not kiwi killers, but they are introduced to New Zealand and they do compete with kiwi for native insects and snails. Hedgehogs also eat the eggs of ground nesting birds. They can be in the bush in large numbers.