Terrestrial vertebrate richness of the inhabited Torres Strait Islands, Australia

Located between New Guinea and Australia, Torres Strait and its islands provide an opportunity to examine the results of recent isolation on the Australo-Papuan fauna. However, records of the modern diversity of terrestrial vertebrates on the islands remained scattered and poorly documented. Analyses of terrestrial vertebrate inventories and physical island variables can provide insight into pre-existing conditions of the Sahul land bridge and useful strategies for conservation efforts. We collated all available records of terrestrial vertebrates from the 17 inhabited islands and supplemented these with our own systematic surveys. We used Spearman’s rank correlation coefficient and nested analysis to determine how species richness relates to physical island variables. We also used cluster analysis to group similar islands based on their vertebrate assemblages. Vertebrate richness is not correlated with Simpson’s habitat diversity but is correlated with total number of habitat types, indicating that rare habitats may contribute disproportionately to richness. The archipelago supports a depauperate Australo-Papuan fauna and the assemblages found on smaller islands are subsets of those on larger islands. Island size is the most effective predictor of species richness, and the analysis reveals that geographically related islands support similar suites of species. The frequency with which our surveys added new records to individual island inventories highlights the need for additional sampling in the region