Biodiversity on islands is vulnerable to introduced species, and the vegetation tends to lack adaptions to mammalian herbivores (Campbell and Donlan 2005). Unfortunately, goats (

) have been established on many islands. Goats alter plant communities and forest structures and threaten vulnerable plant species; the flow-down effect of these outcomes includes increased soil erosion and the reduction of native fauna that share a similar environmental niche (Spatz and Mueller-Dombois 1973, Coblentz 1978, Parkes 1984, Brennan 1986, Coblentz and Van Vuren 1987, Cronk 1989, Walker 1991, Moran 1996, Desender

. 1999, in Campbell and Donlan 2005). In some island ecosystems it has been the case that goats are the most destructive herbivore present (King, 1985). Feral goats are particularly destructive in such environments and cause a huge loss of native vegetation due to their grazing habits. This leads to ecosystem degradation and biodiversity loss (Coblentz 1978; Schofield 1989; Moran 1996; Desender

1999 in Campbell and Donlan 2005).

Goats have been eradicated from approximately 120 islands and there is hope that native communities will recover rapidly (Hamann 1979, 1993, in Campbell and Donlan 2005). The largest islands on which substantial goat populations have been removed are: Lanai Island (Hawaii), San Clemente (USA), Pinta Island and Santiago Island (Galapagos Islands, Ecuador) and Raoul Island (New Zealand) (Campbell and Donlan 2005; Cruz et al., 2009). In general, goat eradication management for islands larger than 500 hectares requires detailed planning and the use of specialised technology, equipment and personnel. Securing funds for eradication programmes may be an obstacle to goat control (Campbell and Donlan 2005). The recent eradication of feral goats from Santiago Island (58,465 ha) in <5 years cost US$6.1 million, and was achieved with a combination of techniques and technologies (Cruz et al. 2009).

The introduction of modern eradication technology has greatly improved the effectiveness of goat control programmes, making goat eradication more likely. Some control methods include the employment of aerial hunting (helicopter), specially trained goat-hunting dogs, Global Positioning Systems and Geographic Information System techniques as well as sterilised goats marked with radiotelemetry collars, called “Judas goats”, which gravitate to, and therefore detect, wild goat herds. Judas goats are used to find wild herds and are especially suitable for finding the last few survivors or to detect the presence of wild goats when it is uncertain whether they have been eradicated. Hunting dogs are particularly useful in situations when goat density is low and vegetation density is high. Aerial hunting is appropriate in situations where there is less ground cover and a higher density of goats. Eradication is always the better option when compared to short-term control. If short-term control is chosen, goats should be kept at low densities.

Although effective eradication technology is available, Benjamin et al. (2011) demonstrate the potential of strategic water management as a non-lethal technique to protect biodiversity from the impacts of feral goats. In the study area in New South Wales, feral goats were found to remain in close proximity to artificial water points. However, they were able to access and impact upon areas of conservation importance which were nearby to these water points. However, by using fencing, the distance the goats needed to travel from the water points to gain access to conservation areas was increased – this protected biodiversity without eradicating the goat population (although the population was locally reduced). This solution was favourable with local landholders some of whom harvest the feral goats.

Guidelines for managing the impact of feral goats have been developed under the Vertebrate Pest Program (VPP) Australia administered by the Bureau of Resource Sciences (BRS). The purpose of these guidelines is to assist in the development of cost-effective strategies to reduce the damage feral goats cause to production and conservation. Management techniques and strategies for feral goat management are recommended and illustrated by case studies. Deficiencies in knowledge, management and legislation are identified. Please follow this link to view and download Parkes, J., R Henzell & G Pickles, 1995. Managing Vertebrate Pests: Feral Goats

Inter-oestrous interval is 20 days; oestrus duration is 40 hours. Ovulation occurs 30 hours after oestrus begins. Oestrus is seasonal only.