Breeding of North Island Brown Kiwi, Apteryx australis mantelli, in Hawkes Bay, New Zealand

Three pairs of kiwis were fitted with radio transmitters and followed for two years in a forest remnant in Hawke's Bay. Laying began in late June or July, when both sexes reached peak weight, and usually finished in November. Twelve of 14 nests were in burrows, 470-900 mm long. Females laid 2-5 eggs each season, 21-60 days apart; clutches which failed in the first few weeks of incubation were replaced. Completed clutches comprised two eggs. A second clutch laid after the first had successfully hatched was recorded only once. Males did all of the incubating and emerged every night to feed, except when chicks were hatching. Their feeding bouts averaged 4.9 h, about half the feeding time of non-incubating kiwis. The weights of both sexes declined during the breeding season—females by about 20% and males by about 13%. Only 6 of 21 eggs laid in the two years hatched. One chick died while hatching, and two died soon afterwards. Three fledged 16-20 days after hatching, giving a productivity of 0.5 chicks/pair/year. The breeding behaviour and mating system of kiwis in Hawke's Bay are discussed.