New Zealand's Pre-Human Avifauna and Its Vulnerability
- Department of Zoology, University of Canterbury, Private Bag, Christchurch, New Zealand
In the past 1000 years New Zealand has experienced a major 'extinction event', losing 40-50% of the avifauna, at least 50% of the frog fauna, and unknown proportions of the lizard and invertebrate faunas. During this period, bird species became extinct at different times and rates depending on the particular aspects of their ecology and life history which made them vulnerable to habitat loss, hunting, predation, and competition for food resources. Three groups of species with different levels of vulnerability are recognised within this event:
Group I, 1000-1200 AD—species susceptible to initial impact of hunting by Polynesians and dogs, and predation and competition for food after an explosive irruption of kiore (Rattus exulans)
Group II, 1200-1780 AD—species more resilient but gradually reduced by Polynesian hunting and continuous clearance and fragmentation of habitat;
Group III, 1780-present—species susceptible to hunting with European weapons and predation by Rattus norvegicus, R. rattus, mustelids, cats, and to competition by mammalian herbivores, and destruction of wet forest and wetland habitat. Climatic change is seen as a negligible influence relative to these major intrusions. Discussions of the pre-human avifauna have so far concentrated almost exclusively on moas (Aves: Dinornithidae, Anomalopterygidae), partly because information on the other extinct species is sparse. The ecology of 12 species in the pre-human avifauna is inferred from their anatomy, relationships to extant species, sub-fossil evidence of diets, and analogy with related forms elsewhere.