Patterns and causes of extinction and decline in Australian conilurine rodents Original Research Article

The conilurine rodents, a predominantly Australian group of almost 50 species, have suffered a higher rate of extinction and decline than other mammalian taxa. Previous theories advanced to explain mammal declines in Australia have not achieved wide acceptance or provided the confidence for initiation of general recovery programmes. This study examined univariate and multivariate associations between conilurine decline and a range of life history (body size, biogeographic province, habitat preference, diet, use of shelter and refuges, reproductive potential, population stability, and rainfall) and land-use parameters (abundance of the introduced fox Vulpes vulpes, cat Felis cattus, rabbit Oryctolagus cuniculus, and domestic stock). Life history associations included an increase in range decline with increasing body size; more severe decline in the arid centre and temperate woodlands; less severe decline in species which have high reproductive rates and those which use shelter (burrows and natural cavities); and a more severe decline in species with a high proportion of leaf/stem in their diets. Declines were most severe in areas where rabbits and foxes were abundant and less severe in areas where dingoes were abundant. The abundance of the cat was the best predictor of decline in small conilurines (<35 g), and in conilurines of all sizes where foxes and rabbits are scarce or absent. An ‘hyperpredation’ hypothesis is advanced to account for these patterns. Declines have been most severe in areas where predator abundance (cat, fox, dingo Canis familiaris dingo) has been greatly elevated and sustained by the introduction of rabbits and mice. Cats and foxes are also associated with severe declines in species with low reproductive rates in areas where rabbits and mice are scarce or absent and where habitats may have been modified by grazing or frequent burning. Rabbit control, construction of small predator-proof fenced enclosures around core breeding populations, and continued transfer of endangered fauna to predator-free islands are advocated to facilitate conilurine recovery.