Proximity to source populations and untidy gardens predict occurrence of a small lizard in an urban area

Abstract

Very little is known about how lizards respond to urbanization. Given their small space requirements, opportunist lizard species can potentially exist in small patches of suitable urban habitat. This study identified the relative importance of landscape and habitat-level factors that influenced the occurrence of an opportunist and generally abundant species, the common skink Oligosoma nigriplantare polychrome in suburban private gardens in New Zealand. Private gardens are potentially important in sustaining urban wildlife as they make up a significant proportion of the total area of many cities. Common skinks were largely absent from the central suburbs and distributed in less highly ordered gardens around the city edge. Skink occurrence was influenced mainly by landscape-level features that reflect opportunities for dispersal into gardens from source populations (distance to city edge; presence of an adjacent grassy paddock) and habitat quality (messiness). To a lesser extent skink occurrence was associated with lower cat densities, less native vegetation and south-facing sites. Within private gardens common skinks were associated with areas with a high proportion of basking surfaces, lower plant species diversity, shorter distances to potential cover, and vegetation that was low in height and made up mainly of long exotic grasses. Despite common skinks’ ability to thrive in exotic vegetation and their small spatial requirements, it is unlikely that they will thrive in urban areas unless gardening practices change to increase resource availability and provide refuges from predators.