Six varieties, four species

Forest and Bird, Issue 292, 1 May 1999, Page 17

Six varieties, four species

n early result was the discovery, by genetic studies in 1993, that there are at least four, not three, species of kiwi. What had been known earlier as the brown kiwi through the country, was found to be two or more quite distinct, although physically similar (cryptic) species. They are now known as the brown kiwi in the north and tokoeka (their Ngai Tahu name which literally means ‘weka with a walking stick’) in the south. The split is not at Cook Strait, but between Okarito and Haast on the West Coast. The Okarito brown kiwi, or rowi, of South Okarito forest is more closely related to the brown kiwi of the North Island than to those living less than 200 kilometres away near Haast, even though they look more like their southern cousins. Among tokoeka, the birds living in the mountains behind Haast are genetically and physically different from those in Fiordland or Stewart Island, being rufous in colour, with a down-curved bill. They are now called Haast tokoeka, while the others are called southern tokoeka. The great spotted kiwi and little spotted kiwi complete the kiwi family. (The current distribution of the six varieties of kiwi is shown opposite.)

The path to extinction

stimated kiwi population figures, projected from the year of Forest and Bird’s foundation and its 1998 jubilee, show the birds will be functionally extinct on the mainland in another 75 years. The figures track the effect of a 5.8 percent annual decline in mainland populations. The offshore island populations, protected from mustelids, are stable for the North Island brown kiwi and the southern tokoeka. Only the number of little spotted kiwi (already extinct on the mainland) shows some improvment on predator-free islands.

1923 1998 2073 North I Brown Kiwi North I 2,640,000 30,000 340 L Barrier I 1000 1000 1000 Okarito Brown Kiwi South I 11,000 130 1 Haast Tokoeka South I 18,000 200 2 Southern Tokoeka South I 530,000 6,000 68 Stewart I 20,000 20,000 20,000 Great Spotted Kiwi South I 1,760,000 20,000 226 Little Spotted Kiwi South I 3000 0 0 Islands 50 1100 1500 Mainland 4,962,000 56,330 637 Offshore islands 21,050 22,100 22,500 Overall 4,983,050 78,430 23,137