Social Organization of North Island Brown Kiwi: Long-term Pairs and Three Types of Male Spacing Behaviour

Abstract

We obcrved i I kiwi b! radiotr-acking for an average period of 2.3 months each, in W'aitangi State Forest, New Zcaland. Spacing data for more than one reproductive season are available from 27 individuals, with intervals of up to six years for some of them. €;emales have a high potential for polyandr!-, especiall!. in the S'aitangi population with a male-biased sex ratio oi 1.4 : I. However, behavioural cvidencc. suggests a monogamous mating system with long-term pair bonds. Pair membcrs tend to stas close to each other and nearly all observed social interactions were between them. We show that there are three types of male spacing behaviour, which are related to the pairing status. A surplus of tully grown males (22.1 'YO in 1986, 37.3 '% in 1987) remained unpaired. About halt ot these bachelor males maintained territories, which were twice the size of paired males' territories. 'This prohahly serves to recruit mates. The other half of unpaired males used huge home ranges of six times the size of paired males' territories, overlapping several territories of conspeciiics. Wc have no evirienct. thar these floaters take part in reproduction.