The Answer

Whether domestic or feral, indigenous or non-indigenous, animal or human, the only cheap, humane, long-term and effective method of limiting a population is by fertility control. The continuing presence of feral animals in Australia, despite on-going campaigns of large-scale slaughter, prove lethal control to be costly, inhumane and ultimately futile. Chemical fertility control is already available. The difficulty is the means of delivery to large populations.

Prof. Jay Kirkpatrick , of the Department of Biological Sciences, Eastern Montana State College, has worked for many years with fertility control of horses and deer. He administers contraceptives remotely by dart from a tranquilliser gun. During his visit to Australia last year to attend the Fertility Control Conference in Queensland, Professor Kirkpatrick was able to report that population levels amongst wild horses and deer in Montana are now dropping - that is natural deaths are exceeding births - by the use of his method.

Fertility Control of Rabbits

The rabbit is particularly suitable for fertility control, as it is a prolific breeder but short lived. If the new generation of rabbits does not happen, or is much reduced, the parent rabbits are not replaced and the parents themselves do not live very long. The problem is to find a contraceptive which can be delivered widely and is specific to rabbits.

When he was first in Australia in 1989 Professor Kirkpatrick suggested that one of the newer synthetic oral progestins could be incorporated into oats or other grain and sprinkled into rabbit dens. Given the very short life of the wild rabbit, he believed that reductions would show up fairly fast. This might be a workable strategy in parks like Tibinnbilli or other defined areas. It would be important to keep the grain in the dens to prevent birds from eating it.