Observations on the effects of rabbit calicivirus disease on low and medium density rabbit populations in western New South Wales

Abstract

Between winter 1995 and winter 1998, seasonal spotlight counts for rabbits were conducted along three transects in western New South Wales. Rabbit Calicivirus (RCV) arrived at the study site in spring 1996 and had an immediate marked effect on rabbit densities. Prior to the advent of Rabbit Calicivirus Disease (RCD), rabbit abundance followed the expected annual pattern of positive growth during the winter to summer period and negligible or negative growth during the summer to winter period. With the arrival of RCV, rabbit abundance was observed to decline by 47% and 75% within low density populations and by 84% within a medium density population. In the subsequent 21 months, the low density populations returned to levels approximating those prior to the arrival of RCV. In contrast, rabbit abundance within the medium density population remained at consistently lowered levels. These data suggest that RCD will have a minimal effect on semi-arid zone rabbit populations below a density of 0.4/ha and that additional management actions will be required to further reduce rabbit abundances.