Feral Animals of the Northern Territory
Feral Horse - Equus Caballus
Impacts
Feral horses cause considerable damage to the natural environment, including increased erosion of soil and waterways, increased spread of weeds, trampling of native vegetation, consumption of native seedlings leading to reduced biodiversity, sedimentation of waterways and water bodies, destruction of infrastructure, competition with native species and domestic cattle for resources, and spread of disease and parasites to domestic stock and native species. Correlative data collected near Alice Springs indicate that feral horses accelerate gully erosion, foul water holes and natural springs and denude large areas of native vegetation. They may also displace native herbivores like kangaroos by removing food and shelter.
Horses will travel up to 50 km for food and water, which means that they have the potential to cause extensive damage over a very wide range.
The economic impact which feral horses have on pastoralism is poorly quantified but likely to be significant. High dietary overlap indicates that the potential for competition between feral horses and cattle for food is high. Horses compete with stock for water which may be a crucial factor during drought.
Background
Horses arrived on the First Fleet in 1788 and the first major influx of horses into Australia was the importation of the Timor Pony at the Port Essington on the Coburg Peninsula in 1838-1849. Shipments of working farm horses were brought to Australia; however, records indicate that these escaped or were abandoned in the early 1800s. This trend increased as machines gradually replaced horses in a range of tasks and many horses were released to join the already established feral herds.
Distribution and Habitat
It is estimated there are 300,000 feral horses throughout Australia, where they inhabit a range of habitats. On average, horses produce one foal every two years, leading to relatively rapid increases in the wild.
In the Northern Territory, major concentrations occur to the west of Alice Springs, in the Gulf region, in the Victoria River District and to the south of Darwin extending as far as Katherine. Feral horses also occur on Vanderlin Island in the Sir Edward Pellew Island Group and on Bathurst and Melville Islands. A small population of Timor ponies still runs wild on the Coburg Peninsula.
Feral horses are common in tropical grasslands and on semi-arid plains which offer the best forage, but are also found in hilly range habitat. Feral horses often retreat to higher relief or heavily wooded habitats to escape drought and/or mustering activities.
Management
The Parks and Wildlife Service implements control of feral horses in most national parks which it manages. Currently there is a major horse control program in the Victoria River District which has been declared a pest control area.
Feral horses can be managed using a number of techniques:
Aerial platform control. This management practice requires extensive training of personnel. It is one of the most effective, environmentally friendly and humane methods of removing large feral animals because it is target-specific. If implemented correctly, will result in a rapid death, with very little suffering to the animal. Helicopter shooting by trained personnel enables coverage of large areas and inaccessible country. It is the only practical way of achieving quick, humane, large-scale population reduction.
Trapping or mustering feral horses so that they may be sold for meat or stock. This technique, while potentially effective is expensive and time consuming over large areas. In addition, in many cases, the numbers of animals that are required by the pet food trade are significantly less than the numbers that are required to be removed for environmental protection and sustainability.
On-ground culling. This technique is humane and relatively cost-effective compared with many of the other techniques, but is limited to accessible terrains.
Fertility control is a non-lethal approach to feral horse management but it is currently of limited use. Fertility control techniques are difficult to administer to large numbers of feral horses and the treatment would need to be repeated often to be effective. There is very little evidence to suggest that this procedure would be effective or feasible for controlling large numbers of feral animals.
