Rabbits in Australia

introduced to Australia in the 1800s by European settlers. Free from diseases and facing relatively few predators in a modified environment, the wild populations grew rapidly. They soon became a problem for colonists trying to establish vegetable gardens and, after the 1860s, quickly spread across the southern two thirds of Australia with devastating impact.

In this section:

History

Domesticated European rabbits arrived in Australia with the First Fleet, brought along as a source of food. European wild rabbits were subsequently introduced, especially as game for hunting. There are reports of many attempted introductions, but not all were successful. A colony of feral rabbits was reported in Tasmania in 1827 and European wild rabbits were released in Victoria in 1859, and in South Australia shortly after. By 1886 they were found throughout Victoria and New South Wales – extending to Western Australia by 1894, and into the Northern Territory by the 1900s. By 1910 feral rabbits were found throughout most of their current range – covering two thirds of Australia.

How rabbits advanced across Australia. (Source: Williams et.al. 1995)

Molecular analysis of current populations reveals a patchwork of varying genetics in rabbits with six main regional groupings across the country, supporting evidence for a history of multiple introductions, followed by regional dispersal. Regional selection pressures may also be at play.

Map of rabbit genetic clusters. (Source: Iannella et.al., 2019)

Distribution & Abundance

Overview of Distribution

By 1920 it is thought there were 10 billion rabbits in Australia. The population is currently estimated to be 200 million. Those rabbits inhabit 70% of Australia’s landmass (5.3 million km2) and are generally widespread wherever they are found.

Estimated rabbit populations in Queensland have been:

  • 150 million in 1949, prior to myxomatosis
  • 5 million in 1995, just before RHDV
  • 2 million in 1996, shortly after RHDV
  • 14 million in 2008 (DPI&F, 2008).

Rabbit populations vary dramatically with seasons and with the introduction of new biological controls. Their ability to breed enables them to rapidly build up numbers after a drought or the release of a new bio-control. The response can be very rapid in good seasons after a drought, but is more gradual after a new bio-control as it attenuates and/or rabbits develop immunity.

Rabbit abundance and Economic costs. (Cox T, et.al., 2013)
Legend: LH axis = Abundance (Line). RH axis = Losses (Triangles).

Rabbits are adapted to the ‘Mediterranean’ climate of their Iberian homelands – a climate with cool, wet winters and hot, dry summers. They do well in similar regions in Australia, but not in the hot, humid tropics. Environmental factors influencing rabbit distribution include:

  • Rabbits are physically stressed by heat and humidity, doing best in places with a mean annual temperature above 10oC and a mean warmest monthly temperature of 25oC or less.
  • Rabbits usually get all the water they need from the plants they eat, except during drought when they require access to water within approximately 0.4 km of their warren.
  • The availability of food is an ephemeral factor, often drive by rainfall. Rabbit densities are generally highest where the total rainfall the year prior was more than about 400mm and the winter temperature was above 4°C, creating good growing conditions.
  • Soil type. Soils with 20-50% clay content are good for burrows, and deep, sandy soils are also preferred burrow sites.

The presence of predators, diseases (including bio-controls), and the control activities of land managers (e.g. baiting, warren ripping and fumigation) influence the incidence of rabbits at a local, district or regional scale.

Field work, monitoring wild rabbits.

For more information see: Rabbit Distribution and Abundance: Information Sheet.

Monitoring & Mapping

Recording the distribution and abundance of rabbits is not a simple matter.

  • Rabbit abundance fluctuates dramatically within and between years. Typically, rabbits breed rapidly with good seasonal conditions, followed in turn by a crash as they either eat themselves out of food – or are affected by a bout of myxomatosis or rabbit haemorrhagic disease.
  • It is often difficult to tell how many rabbits are about. They are nocturnal and live in burrows, concealing the extent of their abundance from many would-be observers. Indicators like warren size, dung counts, and vegetation impacts may be used as proxy measures.
  • Rabbits occur everywhere from urban areas to extremely remote, rarely visited sites, so the effort spent surveying rabbit populations varies greatly across the country. Different methodologies and sampling protocols are used, at different scales and frequencies, making it a challenge to collate and analyse data.

Models have been developed to build on the patchwork of available data. They effectively ‘fill the gaps’ with predictions of distribution and abundance, and help analyse the key factors controlling rabbit populations. The assumptions within a model allow diverse datasets to be analysed, generating maps of potential rabbit distribution and abundance. Every model will have short-comings and the maps generated must be viewed with an appreciation of the assumptions and data behind them, but they provide useful insights about rabbit distribution and the factors influencing it.

For more information see: Rabbit Distribution and Abundance: Information Sheet.

Long-term rabbit monitoring sites, like this one at Turretfield, SA, provide important data for research and modeling. (Image: Louise Barnett)