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Nonnative feral ungulates have both direct and indirect impacts on native ecosystems. Hawai`i is particularly susceptible to biological invasions, as the islands have evolved in extreme geographic isolation. In this paper we explore the ecological impacts of nonnative feral goats (Capra hircus) in the Hawaiian Islands, including both the current state of knowledge and future research directions to address knowledge gaps. Understanding how invasive vertebrates impact island ecosystems is important as it provides an informed context for developing contemporary solutions to pressing management problems. Current knowledge gaps, such as the behavioral ecology of goats and their impacts on specific plant species and communities, limit the effectiveness of ecological restoration and conservation in Hawai`i. Emerging technologies in wildlife tracking and remote sensing will enable a greatly improved understanding of the behavior and ecological impacts of these nonnative animals in what is already a highly degraded ecosystem.

The 2008-2009 Aerial Feral Pig and Feral Goat Shooting Program aimed to reduce feral mammal infestations in the Barnard/Hunter River catchment areas, northern New South Wales (NSW), Australia, over a 2-year period, as well as to provide skills to landholders to manage vertebrate pests. By accomplishing these reductions in pest animal densities, it endeavoured to reduce impacts of feral mammals on soil and water resources and on native flora and fauna, thereby protecting ecosystems and giving benefits to the wider community. The NSW Department of Industries and Energy identified the control area, including the Barnard and Hunter River catchment areas, as having one of the highest populations of feral pigs in northern NSW. The area contains diverse and vulnerable ecosystems of woodlands, remnant rainforest, escarpment, and open grazing areas. Projects were designed to use best practice pest animal management methods, including aerial shooting, followed by a trapping campaign and ground shooting. Stakeholders included NSW National Parks and Wildlife Service, Armidale and Hunter Rural Lands Protection Boards, and up to 336 private landowners. Aerial shooting was undertaken in July, because winter is the most opportune season for this method. In 2008, a total of 913 feral pigs, 650 feral goats, 18 deer, and 4 wild dogs were destroyed. In 2009, 1,338 feral pigs, 900 feral goats, and 336 deer were destroyed, all of which were primary target animals. Trapping and poisoning were used to control feral pigs and an extensive ground-shooting program was put in place to control feral goats and the emerging deer problem. Monitoring of residual populations, through New England Livestock Health and Pest Authority property inspections, and assessment of damage caused by feral animals were undertaken at the conclusion of both projects. Ground trapping continues over a 4-month period, and ground shooting is ongoing and opportunistic.

Many diseases of livestock, such as foot and mouth disease (FMD), rinderpest, pest des petite ruminants, and maedi-visna, are exotic to Australia and contingency plans are in place to counteract their introduction. Epidemic modeling fulfills a vital role in these plans. Feral goats occur at high density with livestock in the high-rainfall zone of eastern Australia. Contact within and between groups of domestic and feral ungulates contribute to the behavior of disease in sympatric populations, and are essential parameters for epizootic models. A project in central New South Wales, Australia is investigating the contacts and home range sizes of feral goats in order to construct models for FMD transmission. Preliminary analysis has shown that contacts between feral goats and sheep were fewer than between feral goats, and that the home ranges of goats in the study were small (

The goat (Capra hircus) was first introduced into Western Australia (WA) over 100 years ago and since this time have been liberated and become feral. Feral goats are now found over much of the semi-arid and arid pastoral areas of the State and as uncontrolled grazers cause significant damage to the rangeland. The use of commercialisation as a control strategy to induce landholders to reduce feral goats has been used. This strategy is appealing for several reasons. It requires little government involvement from agencies responsible for pest control, resulting in low public costs. It returns immediate, tangible profits to landholders for the control effort and it utilizes the pest as a resource, making the programme more acceptable to some individuals. However, it is now clear that a commercialisation policy has not been successful in reducing overall feral goat numbers and the consequent damage. Some reasons for this include; commercialisation requires the creation of an infrastructure to handle the product; immediate economic returns from feral goats become long-term cash flows; long-term benefits are not considered; individual control is undertaken rather than co-operative programmes; feral goats are not included as part of the landholders domestic stocking rate entitlement. If such a policy is to continue it will not achieve the long-term objective of eradication. A feral goat eradication programme has recently been instigated in Western Australia by the pastoral industry. Although, commercialisation is to be used to remove the bulk of the population, such a strategy cannot be used on a long-term basis and follow-up control must be undertaken if the objective of the programme is to be achieved. The prolonged use of a commercialisation policy will result in the preservation of a species rather than the elimination of it.