Possible implications of Rabbit Calicivirus Disease for malleefowl Leipoa ocellata Gould in the north-west of Victoria

Parks Victoria and the Department of Natural Resources & Environment (NRE) are collaborating with agencies from the other States and the Commonwealth of Australia in a national program of detailed monitoring and surveillance of the effects of Rabbit Calicivirus Disease (RCD). A component of the Victorian study involves an investigation of possible changes in fox predation upon malleefowl Leipoa ocellata Gould, 1840, in the wake of reduced rabbit abundance caused by RCD. The study entails measurement of overall fox activity post-RCD, measurement of egg loss from malleefowl nests, and an assessment of any observable changes in fox diet. Measures of fox abundance/activity pre- and post- RCD suggest that the level of fox activity has not declined significantly in the 18 months since the spread of RCD in the Victorian Mallee. This contrasts with a dramatic decline in rabbit abundance giving rise to concerns about the possibility of “prey switching”. Preliminary findings by Benshemesh & Burton (1997) are that there was a high level of egg loss due to foxes in the first breeding season post-RCD (1996/97). The only similar finding was by Frith (1959) in a study conducted from 1953/54 to 1957/58 at the time when myxomatosis first affected rabbit populations in Australia. Initial sampling indicates that rabbits formed a relatively small proportion of the fox diet (approximately 15% of stomach contents) at the time of the initial RCD epizootic. It is too early to draw conclusions regarding any changes in fox diet post-RCD.