How introduced rabbits Oryctolagus cuniculus limit the abundance of red kangaroos Macropus rufus and other native grazers in Australia

The successive releases of myxoma virus, rabbit fleas and rabbit haemorrhagic disease virus in Australia greatly reduced the abundance of introduced rabbits, but also reduced enquiry into any continuing role of rabbits in modifying native pasture vegetation or competing with native grazing mammals. We argue here, however, that despite these biological controls, rabbits still compete with red kangaroos for limited pasture resources such as native grasses. This is based on: (a) long-term trends in kangaroo numbers, (b) increases in kangaroos following removal of rabbits, (c) similarities between the quality of foods selected by rabbits and those needed by young kangaroos, (d) the low availability of native grasses as a food source in degraded arid-zone pastures, (e) correlations between abundance of grasses and abundance of rabbits (negative) and kangaroos (positive) and (f) inadequate alternative explanations. Rabbits remain ubiquitous and even at densities of <1 rabbit ha−1 can change pasture composition and quality. Consequently, our results have major implications for managing and conserving native pastures and native grazing mammals.