Ecological niche and microhabitat use of Australian geckos

Abstract

Modern biological research often uses global datasets to answer broad-scale questions using various modelling techniques. But detailed information on species–habitat interactions are often only available for a few species. Australian geckos, a species-rich group of small nocturnal predators, are particularly data-deficient. For most species, information is available only as scattered, anecdotal, or descriptive entries in the taxonomic literature or in field guides. We surveyed gecko communities from 10 sites, and 15 locations across central and northern Queensland, Australia, to quantify ecological niche and habitat use of these communities. Our surveys included deserts, woodlands, and rainforests, examining 34 gecko species. We assigned species to habitat niche categories: arboreal (9 species), saxicoline (4), or terrestrial (13), if at least 75% of our observations fell in one microhabitat; otherwise we classified geckos as generalists (8). For arboreal species, we described perch height and perch diameter and assigned them to ecomorph categories, originally developed for Anolis lizards. There was lower species richness in rainforests than in habitats with lower relative humidity; the highest species richness occurred in woodlands. Most arboreal and generalist species fit the trunk-ground ecomorph, except those in the genus Strophurus, whose members preferred shrubs, twigs of small trees, or, in two cases, spinifex grass hummocks, thus occupying a perch space similar to that of grass-bush anoles. Habitat use by Pseudothecadactylus australis, Saltuarius cornutus, and Gehyra dubia fit the trunk-crown ecomorph. We provide quantified basic ecological data and habitat use for a large group of previously poorly documented species.