Use of trained dogs to determine the age structure and conservation status of kiwi Apteryx spp. populations

Specially trained dogs are used to locate many threatened bird species in New Zealand during conservation management and research projects. Systematic searches were made in four forest patches in Northland where many Brown Kiwi Apteryx mantelli had been fitted with bands, wing tags, transponders or radio-transmitters over a 12-year period of experimental management. The percentage Of subadult birds found by dogs increased in line with predictions from population models of the changing age structure of the population. The dogs independently found radio-tagged adults and subadults in close proportion to their known abundance. Dogs proved to be an excellent tool to determine the age structure of a kiwi Population. With knowledge of the life history of the species involved, this information was used to make an accurate assessment of the conservation Status Of the study population of Brown Kiwi in Northland. Our results also support the recent downgrading of Little Spotted Kiwi Apteryx owenii from 'Vulnerable' to 'Near Threatened', which was based partly on healthy age ratios found during dog searches on Kapiti Island, rather than on results from a study of their breeding biology on the island which showed unsustainably low chick recruitment.