Goat (feral or wild)
Common name: goat (feral or wild)
Scientific name: Capra hircus
Goats (feral or wild) are declared as an established pest animal in the state of Victoria.
Read more about the classification of invasive animals in Victoria.
History of spread
Feral goats have been present in Australia since early European settlement, with wild populations becoming established due to accidental escape or deliberate release. Early populations were initially concentrated around settlement areas. However, they have since spread across 35% of Australia and occur on many offshore islands.
Goats were introduced to many areas by early settlers, miners and railway construction gangs who used them for meat and milk.
Cashmere and Angora goats were also introduced to Australia in the mid-1800s to start a fibre industry. When this industry collapsed in the 1920s, many goats were abandoned in preference for wool.
The mixed origins of feral goats are reflected in the genetic diversity seen in wild populations.
The greatest numbers of feral goats occur in the arid and semi-arid pastoral regions of Queensland, New South Wales, South Australia and Western Australia. However, it appears their numbers are increasing in parts of the Great Dividing Range.
Distribution in Victoria
There is little information available regarding the distribution and density of feral goats in Victoria. However, anecdotal information suggests that the largest goat populations occur in areas where large tracts of forested or semi-arid areas offer some protection from control and people. Feral goats have also been sighted in many state and regional parks and forests throughout Victoria.
Factors that influence feral goat distribution include food, water and shelter. Occurrence of parasites and diseases as well as predators such as wild dogs are also influential.
There are over three hundred distinct breeds of goat throughout the world, but the Australian feral goat population consists of a mix of Angora, Cashmere, Anglo-Nubian, British Alpine, Saanen and Toggenburg breeds.
Both male and female goats have distinctive curved or corkscrew shaped horns, although some may be hornless. The coats of feral goats vary widely depending on breed and so does their hair type with it being either short, long, curled, silky or coarse. Goats may also have wattles (hanging fleshy lobes) on the neck and beards.
An adult male goat is called a buck, the female is called a doe and juvenile goats are referred to as kids. Colloquially, adult males may be referred to as 'billies' and females as a 'nannies'. Adult goats weigh between 40 and 60 kg while kids weigh about 2.6 kg at birth. Male kids are heavier than females and this is a difference that they retain throughout their lives.
Feral goats are highly sociable animals that form family units typically consisting of an adult female goat and her recent offspring. Family social units associate together to form a herd.
Male kids eventually leave their mothers and form 'bachelor' herds with similar aged males. Feral goat bachelor herds overlap with the female's home range during breeding periods but may range over much larger areas for the rest of the year. Feral goat home ranges can vary from one square kilometre to 600 square kilometres depending on resource availability.
Female goats leave the group to give birth in a protected place such as a rock overhang cave or dense vegetation. Goat kids can follow their mothers soon after birth, but many remain hidden for the first few days and are only visited by their mothers for feeding.
Feral goats are most active during the day and rest at night in regular camp sites. Herd dynamics vary depending on seasonal changes, birth rates and the movements of the male bachelor herds. Feral goats tend to use high or difficult-to-access areas as their night-time camp sites to minimise the risk of predation.
Feral goats often use smell rather than sight to find food and detect predators. As a consequence, they prefer to graze facing into the wind to detect scent.
Goats are reliant on access to water and their home range will revolve around it. The frequency at which goats drink is influenced by environmental conditions. Generally, a herd of feral goats is led by a dominant male. He shares leadership with a dominant female who will usually outlast several dominant males throughout her time.
Among the male goats, horn size can suggest dominance without physical fighting. Adult male goats are also highly reliant on scent to indicate dominance and physical condition. Adult male goats display dominance through a variety of contact and non-contact methods. Non-contact threats include staring, facing a rival with the chin down and horns forward, rushing or rearing. Encounters where physical contact occurs include pushing, head butting, engaging horns and rearing up and clashing.
Feral goats are highly social animals and have reasonably complex systems of communication which includes smell, sight and sound. Alarm behaviour in feral goats is highly developed, making it difficult to drive/muster goats as they scatter when faced with danger. When a female goat detects danger, she will stand rigid with ears towards the source of alarm. Kids respond by running to the relative safety of the female. Female goats may also snort loudly and repeatedly to alert nearby goats to the danger. Depending on the threat, the group may flee, move away slowly, or return to their previous activities.
Feral goats are opportunistic browsers that generally select the highest quality foods available. They will eat:
- plant litter
Despite their tendency to select high-quality foods, feral goats can eat most plant species in Australia. This includes many plants that are toxic, spiny and bitter which sheep and cattle are likely to avoid.
An average-sized goat requires between 2 and 4.5 litres of water per day, depending on temperature. Despite this, some goats in cooler and wetter climates are able to obtain the majority of their water from their food, meaning they are capable of surviving in areas with limited permanent fresh water.
Feral goats can establish populations in any area where food, water and protection from predators is available. In Victoria, feral goats tend to be able to establish and maintain populations in the semi-arid environments of the north west and the mountainous terrain of the Grampians, Alpine and East Gippsland regions.
In mountain regions, feral goats can live at high altitudes where there is food and water available. Goats are skilled rock and log climbers, and regularly use caves and rock overhangs for shelter.
Wild dogs and dingoes are the most significant predators of feral goats in Australia. Feral pigs, crocodiles, foxes and large eagles may also prey upon feral goats, particularly goat kids.
Diseases and parasites
Feral goats are susceptible to many exotic livestock diseases that are not present in Australia including:
- foot-and-mouth disease
- Rift Valley fever
- blue tongue.
Feral goats are also susceptible to several endemic diseases currently found in Australia including:
- Johne's Disease
- Q fever
- pulpy kidney
- various parasitic worms of the gastrointestinal tract.
Additionally, feral goats may also spread diseases to domestic livestock including sheep and goat herds.
Feral goats can breed all year round, but breeding tends to peak during autumn with less in spring.
Feral goat breeding is influenced by environmental factors including drought, population dynamics, food and water availability. Despite variations in breeding seasons, all sexually mature female goats commonly come into oestrus at about the same time.
As many populations of feral goats have a higher proportion of females than males, population growth can be high. It is generally accepted that a population has the potential to double in size every 1.6 years, without human influence or control.
Female goats are sexually mature from six months of age and can produce young twice a year, with a gestation period of only 150 days. Twins and triplets are relatively common among domestic and feral goat populations, but most feral goats tend to have singles or twins.
Dispersal of feral goats depends on availability of food, water and shelter. Feral goats prefer to maintain a small home range and traditional camp sites where possible, but will disperse when food and water becomes scarce. Young female goats will stay with their family group throughout their lives, while males will leave these groups at puberty and join bachelor groups.
From day-to-day large herds may will separate into smaller subgroups during the day and re-unite at night at common camp sites.
Impact on ecosystems and waterways
Feral goats cause considerable environmental impacts through:
- soil damage
- over grazing
As a selective browser, feral goats can drastically impact on specific plant communities over a relatively short period.
Goats are also capable of climbing trees where branches and trunks are on suitable angles, enabling them to graze much higher than kangaroos or sheep. Even when adult trees can survive, the goats will destroy seedlings affecting the rate of recruitment, and limiting the survival of that plant community.
Feral goats compete with many animals species for food, water and shelter. Goat dung around water ways, together with goat carcasses that have fallen into the water, is likely to affect water quality.
Competition and land degradation by feral goats is listed as a key threatening process under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).
Agricultural and economic impacts
Feral goats are a major agricultural pest throughout Australia.
Economic losses because of feral goats can be split into four areas of costs:
- to primary production
- associated with exotic diseases
- of land degradation caused by goats
- to the public to manage goats.
In other Australian states, some costs can be recouped by mustering and selling feral goats. Due to lower numbers and difficult terrain, it’s generally not practised in Victoria.
The monetary value of economic losses in Victoria is unknown. However, the cost to Australia is estimated to be around $25 million per annum. While the largest populations of feral goats occur in Western Australia, South Australia and New South Wales, there are still considerable populations in Victoria.
While feral goats are found mostly on public land in Victoria, they are also found on private property. Feral goats and domestic livestock have overlapping diets and habitats which can cause competition with domestic livestock for food, water and shelter. Feral goats can also out-compete and outlast sheep and kangaroos in time of drought.
Primary producers who own domestic goats may incur costs by having to prevent male feral goats from mating with their females. Foresters also incur costs to production caused by goat damage to their seedlings.
Feral goats are known to be susceptible to several diseases of livestock including Ovine Johne's Disease, foot-and-mouth, rinderpest, rabies and blue tongue. Unchecked wild herds could potentially play a major role in the spread of exotic disease if they are introduced into Australia.
Recommended control measures for feral goats include:
- exclusion fencing.
The department recommends integrated pest management using all suitable control measures in a strategic and coordinated manner at a landscape scale.
Read more about management and control of feral goats.
- Department of Natural Resources and Environment 2002, Victorian Pest Management Framework: A Framework for Action – Feral Pig and Feral Goat Management Strategy, Department of Natural Resources and Environment, Melbourne.
- Feral Goat fact sheet. 2010. Biosecurity Queensland. Accessed on 13th February 2012 http://www.dpi.qld.gov.au/documents/Biosecurity_EnvironmentalPests/IPA-Feral-Goat-PA18.pdf
- Fleming, P and Tracey, J 2003, Methods for Determining Feral Goat Abundance in Rugged Terrain, Vertebrate Pest Research Unit, NSW Agriculture.
- Forsyth D. M., Duncan R. P., Bomford M. and Moore, G. 2004 Climatic suitability, life history traits, introduction effort and the establishment and spread of introduced mammals in Australia.
- McGregor, B 2007, A Guide to the Grazing Requirements of Fibre and Meat Goat, Department of Primary Industries, Attwood.
- McGregor, B 2007, An Introduction to Reproduction Management of Fibre and Meat Goats, Department of Primary Industries, Attwood.
- Parkes, J, Henzell, R and Pickles, G 1996, Managing Vertebrate Pests: Feral Goats, Bureau of Resources, Sciences and Australian Nature Conservation Agency, Australian Government Publishing Services, Canberra.
- Parks Victoria 2008, Annual Report 2007-08, Parks Victoria, Melbourne.
- Parks Victoria 2007, Annual Report 2006-07, Parks Victoria, Melbourne.
- Parks Victoria 2006, Annual Report 2005-06, Parks Victoria, Melbourne.
- Parks Victoria 2005, Annual Report 2004-05, Parks Victoria, Melbourne.
- Parks Victoria 2004, Annual Report 2003-04, Parks Victoria, Melbourne.
- Sharp, T and Saunders, G 2007, Model Code of Practice for the Humane Control of Feral Goats, Vertebrate Pest Research Unit, New South Wales Department of Primary Industries, Orange.
- The Feral Goat Fact Sheet. 2011. Department of Sustainability Environment Water Population and Communities. Accessed on 13th February 2012
Figures 1 to 4 courtesy of Jason Wishart