North Island brown kiwi vocalisations and their use in censusing populations

Vocalisations of the North Island Brown Kiwi (Apteryx australis mantelli) were monitored from March 1981 to July 1982 in Waitangi State Forest, Northland. Calling rates were found to be seasonally cyclic and correlated with breeding. Males calIed more often than females. Four categories of kiwi sounds are described and their possible functions discussed. A census of kiwis based on counts of calls underestimates the population: a banding study in a small area gives a much better indication of kiwi numbers. An estimated 800-1,000 kiwis inhabit Waitangi State Forest. Calling rates are density dependent and so can be used for comparison of kiwi population densities between two areas.