To answer that first question: they must have been once, given the sub-fossil remains from caves within or at least very close to the park. Trying to gather more recent evidence has been difficult.
During the Depression, men were employed cutting fence posts at Canaan and the story goes that they survived on weka, kākā and kiwi. In 1941 a little spotted kiwi was recorded close to Takaka. Speaking with two older men who had family holidays on private land at Onetahuti during the 1940s, there was talk of kiwi having called at night but they were never seen.
In the 1980s large footprints were seen in soft sand on a farm near Canaan and, according to a well qualified ornithologist, these were measured and were consistent with those of a kiwi. Listening at night and playing calls to elicit a response drew a blank. Other reports of hearing a kiwi on this farmland have been occasionally submitted to DOC. And then last year there were two plausible records: two experienced trampers believed they saw a kiwi at dusk near Harwoods Hole, and others were sure they heard one from Wainui Hut.
These recent records have been followed up thoroughly. Acoustic recorders were deployed, firstly by Robin and Sandy Toy and later by Andrew Digby, but no kiwi was ever vocal near these recorders for the scores of nights they were active. We sat out at night and played kiwi calls but without any response. We even collected some very kiwi like droppings but genetic analysis identified them as definitely coming from weka!
Project Janszoon would like to see kiwi introduced into the park, taking advantage of the 15,000 ha where predators are now well controlled. However given that even the great spotted kiwi seems to be absent (whereas it persists strongly in Kahurangi National Park) there have to be doubts about whether the habitat is suitable. We are taking soil samples from a range of habitats and during both winter and summer to see how abundant kiwi invertebrates are. Its early days still but perhaps the porous granite soils are just not suitable.