While living in England, a certain Austin Thomas who had been an avid hunter regularly dedicating his weekends to rabbit shooting, decided to import 24 grey and domestic rabbits from England to his Barwon Park property near Geelong in Victoria in 1859 so that he could continue his hobby in Australia by creating a local population of the species. Australia had no native rabbit population. At the time he had stated, "The introduction of a few rabbits could do little harm and might provide a touch of home, in addition to a spot of hunting."
In a classic example of unintended consequences, within ten years of the introduction in 1859, rabbits undertook the fastest spread ever recorded of any mammal anywhere in the world. Rabbits are extremely prolific creatures, and Australia provided ideal breeding conditions since they were able to breed the entire year. This small population exploded to cover Victoria and New South Wales by 1886 and today rabbits are entrenched in the southern and central areas of the country, with scattered populations in the northern deserts.
Although the rabbit is a notorious pest it proved helpful to many people during the Great Depression and during wartime. Trapping rabbits helped farmers by providing something to eat, extra income and in some cases helped pay off farming debts. Later, frozen rabbit carcases were traded locally and exported. Pelts too, were used in the fur trade and are still used in the felt-hat industry.
Unfortunately rabbits are suspected of being the most significant known factor in species loss in Australia since they tend to kill young trees in orchards, forests and on properties by ring barking them (the process of completely removing a strip of bark around a tree's outer circumference, causing its death).
Rabbits are also responsible for serious soil erosion problems as they eat native plants, leaving the topsoil exposed and vulnerable to sheet, gully and wind erosion. The removal of this topsoil is devastating to the land as it takes many hundreds of years to regenerate. This soil is typically deposited in waterways, causing siltation and destroying aquatic ecosystems.
They also actively compete with domestic livestock and altered pasture composition by selectively grazing on more palatable and nutritious plants leading to destruction of habitat and affecting many native marsupial species such as the bilby and the bandicoot as their feed sources were outstripped by marauding rabbits.
Interventions
In the past, rabbit populations were reduced drastically with the introduction of biological control vectors. In 1950, the myxomatosis virus initially wiped out between 95 and 100% of rabbits in some areas. However, rabbits recovered with the development of resistance in many populations. The introduction of Rabbit Haemorrhagic Disease or Rabbit Calicivirus (RHDV or RCD) also helped control populations, especially in arid areas, but again, rapid resistance to RCD has left rabbits as one of Australia's most formidable pests.
Other actions for rabbit control include:
- fumigation of warrens;
- fencing;
- destruction of warren systems;
- removal of rabbit harbour; and
- shooting.
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ReplyDeleteBrian this is a great overview of the rabbit problem in Australia and how someone's addition of a nonendemic species became a big problem for the country. There were two changes which I would recommend for your CDL.
ReplyDelete1. It is unclear to me how an increase in species loss can positively relate to an increase in rabbit population. There may not be a link there.
2.I am curious to know what the unintended consequences of the rabbit management policy were. Did the near demise of the rabbits affect any other species or natural cycle on the island negatively?
I was glad to see that you included siltation and aquatic ecosystem loss as variables to your CDL.
Thks for the comments Megan. very possible the cld is not complete for to answer your questions:
ReplyDelete1. unfortunately the species loss meant that there was less competing species for vegetation and preadtors, hence increased food for rabbit population and more reproduction.
2. very good question and quite frankly didn't get into it. I will look it up when this blessed credit eases up, and gives us time to explore a bit and digest it a bit further: )
I swear my next cld will be about how the pursuit of systems thinking is leading to a no of unintended consequences like girlfriend impatience, zero house maintenance, distraction from work and fatigue hehe.
have a good evening.