Changes in the diversity of New Zealand forest birds

Abstract

Shannon diversity indices for several subfossil assemblages of New Zealand birds are compared with estimates for living communities today. As expected, bird species diversity was higher in the pre-human environment, but it was also greater than that predicted from studies of living communities. Previous estimates of the number of terrestrial bird species in the pre-human avifauna are too low, and many of these were incorrectly interpreted as being open-country species. The pre-human fauna was deficient in open-country birds. A prediction based on biogeographic (species-area) theory that this deficiency in open-country species was filled by half the species of moa (Dinornithiformes) is not supported by palaeoecological evidence. The major fall in bird species diversity in New Zealand is linked to the type of forest removed in Polynesian times, as well as the area.