With an estimated population of 13,000, the Rakiura tokoeka is the most abundant of the tokoeka taxa, but recent research shows that at least one population, in Mason Bay, is in decline. Thirteen pairs of birds in adjacent territories are being monitored to try to establish why.
It may be because of cat predation or because the Bay’s habitat is changing – the study area is reverting from farmland back to scrubland, which does not suit the kiwi as well as food is harder to find.
In 2009, a second comparative study site was set up at Port Adventure, which has a more stable forest environment.
The Rakiura tokoeka is considered by the Department of Conservation to be ‘threatened (nationally endangered)’, and it is vital that the island remains free of stoats and ferrets.
As with the Fiordland tokoeka, there is no direct management of the Rakiura birds as the population is large. It is estimated that just 1.9% of the Rakiura taxa are actively managed (250 birds). Kiwi researchers predict that, if no management changes are made, their population will decline by 1.8% by 2030.
The kiwi do benefit from occasional aerial 1080 operations. Research is ongoing to gather important information about the status and trend of the population, and possible causes of decline.
Rakiura tokoeka live mainly in the southern two-thirds of the island – researchers think the different geology to the north is not to the birds’ liking.
Some kiwi live in sand dunes along the coast, while others prefer the tussock grass high on the Tin Range. Birds are also found in areas of scrub and bush, and often live in family groups. Female kiwi can often be seen feeding during the day, possibly because during the summer breeding season the southern nights are relatively short.
The kiwi’s territory size varies enormously depending on the habitat. In the sand dunes, family groups can command 50-hectares, while in the tussock grassland of Mason Bay, just 5-hectares can suffice. The size seems to depend on food supply, with larger territories required where food is more difficult to find.