The invasion of the feral goat

While it’s common to hear about the impact of feral rabbits, foxes and cats on the environment, they are not the only feral animals causing problems in Australia – introducing the feral goat.

While domestic goats are present on all continents except Antarctica, the problem of feral goats is unique to Australia, New Zealand and some small islands.1

Feral goats now occur across 28% of Australia and are most common in the rocky or hilly semi-arid areas of western New South Wales, South Australia, Western Australia and Queensland.2

According to Robert Henzell at the AVA Annual Conference in May, feral goats are in such abundance in some places due to a number of factors.

“Feral goats have few natural predators, their biggest threats being people and dingoes. They have a high reproductive rate with populations able to increase by 60–75% a year, wide eating habits, high mobility and are relatively free of parasites and diseases due to the dry Australian environment,” said Dr Henzell.

So what impact are these animals having on the environment? They have been blamed for competing with and causing the decline of native animals, causing soil erosion, overgrazing native plants, polluting natural waters and having the potential to harbour and spread exotic animal diseases, such as foot-andmouth disease.

Several methods have been used to attempt to control the feral goat population; one is the use of mustering. “This technique can work well, especially when aerial mustering is used in flat areas with little vegetation. It can achieve clearance of 80–90% of herds, and afford about three years before goat numbers return to pre-mustering levels,” said Dr Henzell.

Other methods are slightly more inventive, such as the Judas goat.

“Judas goats are fitted with radio transmitters and released into the wild to join a feral goat herd. The Judas goat is then traced and the herd is either shot or captured, while the Judas goat escapes and joins another herd,” he explained.

“It is most useful for feral goat eradication in high rainfall areas, and for exotic disease control.”

One notable success in the eradication of feral goats has been achieved on Kangaroo Island, where goats have been removed from most of the Island’s range and are believed to remain only along a small section of the north coast.

This has been achieved through the efforts of the Kangaroo Island Natural Resources Management Board (KINRMB), with financial and technical assistance from the Invasive Animals Cooperative Research Centre and state government agencies.

“Eradication in this area is likely by 2012, in which case the KINRMB will have achieved the largest island feral goat eradication anywhere in the world,” said Dr Henzell.

Proceedings of the AVA Annual Conference are available to AVA members in the SciQuest online library via www.ava.com.au/veterinarians/sciquest.

Jennifer Bolton
Communications Officer

1. Parkes J, Henzell R, and Pickles G. (1996). Managing Vertebrate Pests: Feral
Goats. Australian Government Publishing Service, Canberra. 129 pp.
2. The Feral Goat (Capra Hircus). www.environment.gov.au/biodiversity/invasive/
publications/pubs/feral-goat.pdf. Accessed June 2011.

This story appears in the July 2011 issue of the Australian Veterinary Journal

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