A literature review of the impact of rabbits on Australian vegetation and ecosystems highlighted the effects of rabbits on a wide range of native trees and shrubs. By removing seedlings and promoting weeds rabbits are a significant factor contributing to native vegetation decline and biodiversity loss.
Despite rabbits having been kept low for some years by Rabbit Haemorrhagic Disease, a survey of remnant vegetation at 220 sites adjacent to farmlands in south-eastern Australia indicated that rabbits were present in 54% of sites visited and were causing noticeable vegetation damage in 26% of sites (i.e. about half the infested sites). Rabbits are more widespread in south-eastern South Australia, western Victoria and Tasmania than in eastern Victoria, New South Wales and south-east Queensland.
A major result from this survey is that low numbers of rabbits (1 - 2/ha) are capable of removing all seedlings of the more palatable native tree and shrubs and exacerbating weed competition with native flora. However, most land managers are not aware that a problem exists except where acute rabbit damage is observed.
Data obtained during the survey have been used to develop and calibrate rapid methods for scoring rabbit abundance and vegetation damage. This has enabled development of an assessment tool that land managers can use to quickly reach a decision on actions necessary for reducing rabbits and maintaining biodiversity. It is applicable for native vegetation on roadsides, reserves and natural shrub-lands used for pasture. The method has been tested using Landcare groups, farmers and government agency staff and progressively improved to increase its robustness and practicality.