Territory, distribution and dispersal of the North Island Brown Kiwi (Apteryx australis mantelli) were studied at Waitangi State Forest, Northland, from February 1981 to July 1982. In all, 84 kiwis were banded and individually coded and 220 resightings were recorded. Weights and bill measurements are given, together with some growth rate data. Territories of 23 birds are shown and these approximate 5 ha per adult pair, but territory size may decrease with greater abundance of food and with immigration from logged areas. Kiwis frequent many burrows within fixed territories, and males defend these territories from other pairs, primarily by calling. Juveniles under 1 year old are accepted in these ranges, whereas larger juveniles and some females do not have regular haunts. Kiwis try to retain their territories in the face of logging and other forest management practices and this behaviour demonstrates the importance of site attachment. Swamp margins and swamp arms are important to kiwis as a temporary refuge after clearfelling and as feeding areas during dry periods of the year. Despite the forestry practices the Waitangi kiwi population is thought to be viable.