Little spotted kiwi only occur in New Zealand, where there are around 1500 individuals remaining. They are the smallest kiwi species, about the size of a bantam hen, and are very susceptible to predation by introduced mammals, such as stoats and dogs. Today they survive on predator-free offshore islands and the fenced mainland sanctuary Zealandia in Wellington.
Although little spotted kiwi currently have a very restricted distribution, deposits of bones (e.g., in caves) indicate that they used to occur throughout New Zealand.
When did little spotted kiwi disappear from the mainland?
Little spotted kiwi in the North Island were already very rare when Europeans settled New Zealand. Only one or two live birds have ever been collected from the North Island mainland for museum collections, both in the 19th century.
In contrast, little spotted kiwi were common on the west coast of the South Island at this time. When exactly they disappeared from the South Island is unclear, with misidentification with the related great spotted kiwi adding to the confusion. However, it has been widely reported that South Island little spotted kiwi went extinct in the 1930s. Other researchers disagree and think that little spotted kiwi were present on the west coast for much longer.
Our recent study has shed light on this debate. We used DNA to identify to species three dead kiwi found in the South Island that post-date the 1930s. These kiwi are now held in Te Papa’s bird collection.
We were able to show that a kiwi specimen found in 1952 from central Westland and two other kiwi specimens found in 1978, from NW Nelson and south Westland, were all little spotted kiwi (as opposed to juvenile great spotted kiwi). This suggests that little spotted kiwi survived, and were widespread, in the South Island until much more recently than generally accepted.
Little spotted kiwi today all originate from a few individuals from Kapiti Island and are highly inbred with very little genetic diversity. This may mean they have reduced resistance to new diseases and an increased risk of genetic defects. If there was more certainty about the identity of the remaining mainland birds in the 1970s perhaps more effort could have been made to locate and move surviving little spotted kiwi to predator-free islands. This would likely have boosted the genetic diversity surviving in this species today.
This result demonstrates how little we know about our native species, even the prominent ones like our (unofficial) national bird, the kiwi. If so little was known about kiwi, then what about other reclusive members of our fauna thought to be recently extinct, such as South Island kokako, or less charismatic but equally interesting species, such as our greater short-tailed bat (Mystacina robusta)?
It doesn’t surprise me that there could have been little spotted kiwi post-1940 that survived on the west coast of the South Island. Having visited the area on numerous occasions, i am always impressed by the sheer ruggedness of the place.