The European rabbit, Oryctolagus cuniculus, is native to the Iberian Peninsula but has become one of the most destructive invasive species globally. Rabbits are highly prolific breeders with few natural predators in their introduced ranges, allowing their populations to explode and profoundly alter ecosystems, causing extensive environmental and agricultural damage. Preventing further incursions and managing existing populations requires a comprehensive strategy that integrates strict biosecurity measures with proactive control methods.
Preventing Establishment Through Biosecurity and Monitoring
Preventing the initial establishment of European rabbits in new territories is the most cost-effective approach. This strategy relies heavily on maintaining strict biosecurity protocols at all points of entry, including ports and borders. Inspections must be thorough to intercept any live animals, equipment, or materials that could harbor rabbits or their eggs.
Strong legislation is necessary to prohibit the importation, transport, or release of rabbits, backed by significant penalties for non-compliance. Early detection systems are equally important, focusing on surveillance in high-risk areas like urban fringes and agricultural zones. Reporting campaigns mobilize the public and landowners, allowing for rapid identification of isolated populations. If a new population is detected early, immediate and intensive eradication efforts can be launched before the animals establish complex warrens.
Direct Management Strategies
Direct management focuses on physical and chemical methods suited for localized control or integrated programs. Exclusion fencing is a common physical barrier, but it must be constructed with specific dimensions to be effective against burrowing animals. Rabbit-proof fencing typically involves a mesh of no more than 40-50 millimeters, with the wire extending at least 150-300 millimeters below the ground and bent outwards to deter digging.
Warren destruction eliminates the complex underground breeding and shelter systems rabbits rely on. Techniques include deep ripping, which uses heavy machinery to collapse and churn the soil to a depth of up to 600 millimeters. Fumigation involves introducing chemical agents like phosphine gas directly into the warrens, which are then sealed to suffocate the rabbits inside.
Chemical control, such as baiting with restricted poisons like Pindone or 1080 (sodium fluoroacetate), quickly reduces high-density populations. These agents are strictly regulated to minimize risk to non-target wildlife, often requiring pre-feeding with non-toxic baits to ensure only rabbits consume the poison. Trapping is used in sensitive areas where other methods pose a higher risk, but it is labor-intensive and not scalable for large infestations.
Biological Control as a Population Suppression Tool
Biological control leverages species-specific pathogens to suppress large rabbit populations where physical methods are impractical. The introduction of the Myxoma virus, causing Myxomatosis, achieved initial mortality rates exceeding 90% in some areas following its release in the 1950s. This success demonstrated the potential of viruses to manage widespread populations.
The Rabbit Haemorrhagic Disease Virus (RHDV) was introduced as a second wave of biological control in the 1990s after rabbits developed resistance to Myxomatosis. RHDV caused significant population crashes, particularly in arid regions. However, its effectiveness is challenged by host-pathogen co-evolution, as rabbits naturally develop genetic resistance to the viruses over time. This resistance selects for more tolerant individuals, leading to a recovery in population numbers.
The emergence of new strains, such as RHDV2 (which appeared around 2015), demonstrates the ongoing evolutionary arms race between the rabbit and the virus. RHDV2 is concerning because it affects younger rabbits previously immune to the older strain, leading to an average population reduction of about 60% upon initial spread. Constant monitoring and the development of new viral strains are necessary to maintain high suppression levels against evolving resistance.
Long-Term Policy and Ecosystem Recovery
Sustained prevention and recovery require coordinated governmental policy and long-term funding. Effective control relies on integrated pest management, where biological control agents are consistently followed up with localized physical destruction of warrens and habitat removal. Legislation must mandate that control efforts are coordinated across neighboring land tenures to prevent re-infestation from uncontrolled areas.
Beyond population suppression, ecological restoration is needed to help landscapes recover from the effects of rabbit grazing and burrowing. This includes reseeding native vegetation and managing bare ground susceptible to wind and water erosion. Protecting native species that rely on the recovered landscape is a natural outcome of sustained rabbit control. Commitment to this continuous process, rather than short-term campaigns, determines the long-term success of rabbit prevention.