Islands and scales: a biogeographic survey of reptiles on Kimberley islands, Western Australia

WA Museum Records and Supplements | Updated 7 years ago

ABSTRACT – The Northern Kimberley region in north-western Australia has high biodiversity and conservation values, including a rich herpetofauna with high levels of endemism. To date, the numerous islands off the coast have been little surveyed. We surveyed 24 of the largest islands along the Kimberley coast for reptiles between 2007 and 2010, to improve our understanding of biogeographical patterns of the region and to locate populations of species that may be threatened by factors including changed fire regimes and Cane Toad invasion. We recorded 79 species of terrestrial reptiles. Species richness ranged from 14 to 32 taxa per island (mean = 22), and tended to increase with island area. Many taxa (36.7%) were Northern Kimberley endemics, 10 of which are only known from island populations. There were numerous new records for islands, range extensions and the discovery of at least three new taxa. Classification based on species presence/absence data identifi ed several distinct clusters of islands, with geographical location of islands, extent of rugged, rocky habitat and climatic gradients at a regional scale having important infl uences on reptile communities. The main cluster of nine islands with the greatest species richness, including richness of Northern Kimberley endemics, was located in the high rainfall zone of the north-west Kimberley. Islands in this cluster were also generally larger in size and they were the most rugged. Island clusters in the mostly drier areas to the north and south had less diversity and often different taxa to the north-west Kimberley cluster. The remaining islands—Adolphus, Sir Graham Moore, Mary and Kingfi sher—were all distinct in the classifi cation analysis. The Kimberley islands harbour unique taxa and reptile assemblages, as well as numerous species known to be vulnerable to Cane Toad toxins and, as such, are important conservation refuges. Careful consideration is required of any proposals to develop the islands, and ongoing surveillance and quarantine is necessary to prevent the introduction of invasive species.