Chapter 7

Possible problems concerning escaped stock

One aspect of rabbit keeping, which is of major concern to many developing countries, is the potential threat to other agricultural enterprises of escaped domestic stock. The unfortunate experience of the Australians is no doubt responsible for this. The genus Oryctolagus, to which the European rabbit belongs, is widespread in Europe and Australia. There are 8 other genera in the family Leporidae to which rabbits and hares belong. The family is widespread in the world but is nowhere very numerous (apart from Europe and Australia), particularly not in the tropics. On certain islands, however, domestic rabbits have multiplied almost regardless of climate from sub-arctic regions to the tropical Phoenix Island only 4°S from the Equator (Flux, personal communication; Watson, 1961).

Unless the rabbit breed is genetically very pure it can revert to the wild type quite quickly: A male and 3 female white rabbits liberated in 1954 on Middleton Island, Alaska, had increased to 5,000 of various colours by 1962 (O'Farrel, 1965). Exdomestic stock thrive in the wild on small islands, especially where there are no competing lagomorphs or predators such as cats. They have established themselves successfully on Hawaii, San Juan (USA), Robben Island (South Africa), Kerguelan, Enderby and other islands off New Zealand and Japan, exhibiting a wide range of environmental tolerance. It is important to note, however, that on Enderby Island (Auckland), a genetically pure strain of the Argente de Champaign breed was liberated and has remained true to form since 1840. rabbits liberated on Moturiau Island (New Zealand) reverted to wild type colour and remained about 30% heavier than ordinary New Zealand wild type rabbits exterminated in 1962 (Flux, personal communication).

Thus in areas such as the Tonga Islands where an interest in rabbit production has been shown (Nance, personal communication), extreme caution should be taken and only very pure genetic strains should be considered (Fenner and Ratcliffe, 1955). In Tonga, escaped rabbits could not be eradicated by hunting and poisons would be difficult to use because of the danger to people and stock. It took 4 years of hard effort (guns, gas poisons and use of helicopters) to clear feral rabbits from a flat 9 acre island off the New Zealand coast (Flux, personal communication). It should also be noted, however, that on the small heavily populated island of Malta, domestic rabbits have been kept for many years without problems. The island also has a population of wild rabbits (genus Oryctolagus).

On large islands and mainland areas without native lagomorphs, domestic rabbits have spread only slowly, if at all, for example Silver Grays on the South Island of New Zealand and domestic rabbits from Tierra del Fuego on the Patagonian mainland.

Domestic rabbits from San Juan have been liberated in many states of America without establishing even temporarily. There, they face competition with indigenous rabbit breeds and suffer the attentions of predators. Wild-type rabbits would differ from the domestic breeds and would have a better chance of establishing themselves and would be far more difficult to control.

In Australia in the mid 19th century, domestic rabbits were kept in almost every town and city, and were known to have escaped or have been liberated but they remained in the locality and gave little or no trouble (Fenner and Ratcliffe, 1955). The trouble in that country only began when wild rabbits were released. Stodart and Myers (1964) consider that the behaviour patterns of domestic rabbits, which sleep on the surface by day, render them more susceptible to predators. The burrowing habit, which provides wild rabbits with a microclimate of moderate stable temperatures and relatively high humidities, undoubtedly helps them to withstand periods of very high ambient temperatures and water shortage in warm countries (Hayward, 1961).

It is worth emphasising here that all successful mainland invasions, i.e. Europe, England, Australia, New Zealand and South America, have sprung from wild stock. Even in Australia, where the invasion was spectacularly successful, wild rabbits have not permanently colonised the tropical parts of the country (Myers and Parker, 1965). The distribution is confined mainly to the southern third to half of the continent, which has a climate similar to the Mediterranean area from which they came.

Before domestic rabbits are introduced to a country where they have not previously existed, particularly in the case of small islands, expert ecological advice should be sought.