Objective 2 – Improve knowledge and understanding of the impact of rabbits and their interactions with other species and ecological processes
The biology and ecology of rabbits has been extensively studied throughout Australia, but a clear understanding of the interactions between rabbits and other fauna, as well as their contribution to a range of environmental processes is still not well understood. Many studies describe economic losses to agriculture, but for the environment, very little information on the value and extent of these losses has been readily quantified. Further, many land managers consider rabbits to be under control through the use of biocontrol agents, but there is little understanding of how even one rabbit can significantly impact native vegetation and how integrated control measures can enhance outcomes.
There is a paucity of research about the exact contribution of rabbits to the diet of native or introduced predators and the potential trophic-cascade effect that rabbit control, or even introduced predator control, may cause (e.g. increase in rabbit numbers, augmentation in resource competition with native herbivores, increase of predation on native prey species). For example, in semi-arid Australia, rabbits have been reported as a staple (and in some cases, primary) prey species for introduced species such as feral cats and foxes, and are thought to directly influence the abundance of these predators (Read & Bowen 2001; Holden & Mutze 2002; Glen & Dickman 2005). The abundance, survival and breeding of eagles, such as the wedge-tailed eagle (Aquila audax), has also been previously thought to be directly related to rabbit abundance, but some recent research is proving otherwise (see Olsen et al. 2014). It is therefore imperative that more conclusive information on potential impacts is garnered.
Key actions for Objective 2 focus on improving our understanding of the impacts of rabbits and the interaction of rabbits with other species, in order to use this information to optimise integrated rabbit control measures.
Action 2.1 seeks to further investigate the interaction between rabbits, feral cats, foxes and wild dogs to enable more effective integration of control activities for these species. Research is envisaged to focus on how predator abundance fluctuates in response to rabbit control, and the nature of the shift in predation to native species in response to rabbit control. This research is expected to help land managers to determine and anticipate any unexpected consequences (direct and/or indirect) of proposed control actions. Such assessments may save land managers considerable flow-on remedial management costs, and help to ensure the previous control actions have a positive outcome (Bergstrom et al. 2009).
Action 2.2 seeks to further investigate the correlation between rabbits and weed species and increase our understanding of the benefits of integrated management. Previous research has suggested that high levels of grazing and soil disturbance by rabbits around warrens is likely to promote the growth of introduced plant species, especially invasive weeds (Williams et al. 1995; Cooke 2012b). By understanding the correlation of rabbits and weeds, land managers should be able to respond more cost-effectively and efficiently to both invasive species.
Action 2.3 aims to continue research into whether or not rabbits sustain populations of native species (i.e. act as a main component of their diet), and whether rabbit control has any implications for the survival of these populations. In particular, research should aim to create a greater understanding of how native predators respond to a sudden and widespread reduction in rabbit numbers.
Control program planning demonstrates consideration of unexpected consequences of proposed actions.
Control programs demonstrate use of integrated control measures for pest species that interact with rabbits and for weed species promoted by rabbits.
Research papers are published that inform whether rabbit control is detrimental to the survival of native species.
2.1 Continue research into understanding the contribution of rabbits in maintaining feral cat, fox and wild dog numbers in different landscapes, and any potential effects of modifying pest predator populations (e.g. prey switching, decline in native species)