Ecological attributes correlated with human-induced rarity of the New Zealand lizard fauna: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Science (Honours) at Lincoln University

Abstract

Forty percent of New Zealand lizard species are now rare, threatened or endangered and occupy only parts of their former range. Conservation of these species is in need of a sound theoretical grounding to base management decisions. Factors thought to have caused range contractions, and thus induced rarity, have been inferred from circumstantial evidence. The validity of these assumptions is questionable. I used a Proportional Odds Model to determine if five ecological attributes, and taxonomy, were significantly correlated with induced rarity in New Zealand lizards. Habitat, body size and genus significantly predicted patterns of induced rarity in the New Zealand lizards. The results of this study suggest that habitat modification and predation by introduced mammals were important causes of range restrictions. Contrary to interpretations made by previous authors, nocturnal and terrestrial species were no more vulnerable than diurnal and arboreal species, having controlled for differences in habitat and body size. In addition, species in different genera showed different patterns of induced rarity, having controlled for habitat and body size. This suggests there may be ecological attributes other than those included in this study which predict patterns of induced rarity. The implications of the above findings for the conservation of New Zealand lizards are illustrated with a study of the lizard fauna of Quail Island. Patterns of induced rarity were explained by examining the ecological attributes of extant and extinct species and the effects of human modification to Quail Island. I discuss the importance of correctly identifying factors that caused induced rarity patterns on Quail Island to ensure success of the proposed restoration of the island's lizard fauna.