General Impact
Biodiversity on islands is greatly threatened, making the introduction of herbivores a great risk (Campbell and Donlan 2005). Unfortunately, goats (Capra hircus) have been established on many such 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 et al. 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 in native vegetation due to their grazing habits. This leads to ecosystem degradation and biodiversity loss (Coblentz 1978; Schofield 1989; Moran 1996; Desender et al. 1999 in Campbell and Donlan 2005).
Location Specific Impacts:Anguilla 
Habitat alteration: Goats are having a major detrimental influence on vegetation of Anegada Is. (Miller et al., 1999 in Varnham 2006) and other islands where they are present.
Threat to endangered species: It is believed that feral goats compete with the native 'Vulnerable (VU)' lesser Antillean iguanas (see Iguana delicatissima in IUCN Red List of Threatened Species) for food, and alter plant community structure by selective browsing. Feral goats can also damage sensitive iguana nesting sites by trampling (Cronk, 1986 in Varnham, 2006).
Goats also impact on the largest colony of Magnificent Frigatebirds (Fregata magnificens) in the E. Caribbean (Davis et al., 2001 in Varnham, 2006). Anegada Is. (British Virgin Islands)
Habitat alteration: Feral goats, Capra hircus are having a major detrimental influence on vegetation of Anegada Is. (Veitch, 1998 in Varnham, 2006) and other islands where they are present.
Reduction in native biodiversity: Feral goats, Capra hircus also impact on the largest colony of Magnificent Frigate birds (Fregata magnificens)in the E. Caribbean (Woodfield, 2005 in Varnham, 2006). Great Tobago Is. (British Virgin Islands)
Habitat alteration: Feral goats, Capra hircus are having a major detrimental influence on vegetation of Anegada Is. (Veitch, 1998 in Varnham, 2006) and other islands where they are present.
Reduction in native biodiversity: Feral goats, Capra hircus also impact on the largest colony of Magnificent Frigate birds (Fregata magnificens)in the E. Caribbean (Woodfield, 2005 in Varnham, 2006). Bay Cay (Cayman Islands)
Threat to endangered species: Capra hircus pose a serious threat to the the native 'Critically Endangered (CR)' Turks & Caicos rock iguana (see Cyclura carinata in IUCN Red List of Threatened Species), presumably through competition for food plants, altering the vegetational composition of habitats and trampling soft substrates where iguanas burrow or nest (Alberts, 2000 in Varnham, 2006; Mitchell et al., 2002 in Varnham, 2006). Major Hill Cay (Cayman Islands)
Threat to endangered species: Capra hircus pose a serious threat to the the native 'Critically Endangered (CR)' Turks & Caicos rock iguana (see Cyclura carinata in IUCN Red List of Threatened Species), presumably through competition for food plants, altering the vegetational composition of habitats and trampling soft substrates where iguanas burrow or nest (Alberts, 2000 in Varnham, 2006; Mitchell et al., 2002 in Varnham, 2006). Parrot Cay (Cayman Islands)
Threat to endangered species: Capra hircus pose a serious threat to the the native 'Critically Endangered (CR)' Turks & Caicos rock iguana (see Cyclura carinata in IUCN Red List of Threatened Species), presumably through competition for food plants, altering the vegetational composition of habitats and trampling soft substrates where iguanas burrow or nest (Alberts, 2000 in Varnham, 2006; Mitchell et al., 2002 in Varnham, 2006). Îles des Saintes (Guadeloupe) 
Herbivory: At the Saintes Islands, populations of wild goats have greatly contributed to changes in the landscape and the structure of vegetation. An August 2007 survey by the Guadeloupian Orchidophile Association revealed that the protected orchid Brassavola cucullata is heavily grazed on Kahouanne Islet, one of its last remaining areas of occurrence (Feldmann, pers. comm., 2007). Mayotte
Herbivory: Although there is no information on the impact of grazing goats on native vegetation, goat grazing is a very important cause of erosion on Mayotte, especially in dry areas (Barthelat, pers comm, 2007). New Caledonia (Nouvelle Calédonie)
Herbivory: The impact of Capra hircus on biodiversity of New Caledonia is not well documented. On a dry forest site in Province Sud goats and the rusa deer (Cervus timorensis russa) are preventing the regeneration of indigenous and endemic plants, and they threaten an endemic woody plant (Ochrosia inventorum) whose current known distribution is limited to this site, with extinction (De Garine-Wichatitsky et al., 2004). Auckland Is. (sub-Antarctic) (New Zealand)
Reduction in native biodiversity: In a study conducted by Chimera, Coleman and Parkes (1995) the rumen contents of 49 goats (captured in 1989) were identified and the dry weight of each component was measured to produce a breakdown of the diet of this small remnant population of feral goats on Auckland Island (a subantarctic island with a cold and harsh climate located south of New Zealand). Woody plants and grasses made up the bulk of their diet (41% and 39%, respectively); seaweeds made up 13%, ferns 4% and herbaceous species 3%. At least 40 plant species were eaten by the goats, but only three species, rata (Metrosideros umbellate), snow tussock (Chionochloa Antarctica), and kelp (Durvillea Antarctica), made up half of the total. Rata (Metrosideros umbellate), Coprosma foetidissima, Pseudopanax simplex and Carex appressa were the most commonly found species - eaten in at least some quantity by 90%, 80%, 76% and 69% of the goats (respectively). Unidentified grasses composed 21.4% of the total contents (dry weight) and were found in 100% of goats. New Zealand
Herbivory: Goats have been recognised as “the single most destructive herbivore” introduced to the islands of the world (King 1985). By eating young trees in a forest they prevent the replacement of adult trees that form the forest canopy. Banks Peninsula (New Zealand)
Ecosystem change: The potential impact of goat browsing on Banks Peninsula is large, as goats are able to reach all but the most inaccessible land in the area, threatening the numerous unique plant communities and endemic plants found on the peninsula (Parkes 2003).
Modification of successional patterns: Natural successional processes that occur in the unique native plant communities on Banks Peninsula may be indirectly disrupted by goat browsing (Parkes 2003).
Reduction in native biodiversity: Native plants that are particularly palatable to, and favoured by, goats on the Banks Peninsula include mahoe (Melicytus ramiflorus), pate (Schefflera digitata) and large-leaved coprosma (Parkes 2003).
Threat to endangered species: The populations of feral goats and pigs on Great Barrier Island threaten the survival of several endangered New Zealand species. These include the kokako (see Callaeas cinerea in IUCN Red List of Threatened Species) and Hochstetter’s frog (see Leiopelma hochstetteri in IUCN Red List of Threatened Species), and several plants including Mestegis apetala and Fuchsia procumbens (Parkes 1990). Macauley Is. (New Zealand)
Reduction in native biodiversity: Sykes (1969) was convinced that some of the endemic species once present on Macauley Island were eliminated due to goat browsing. Raoul Is. (New Zealand)
Habitat alteration: Browsing of native vegetation by goats on Raoul Island has caused changes in the vegetation structure of the forests because of the unpalatability of the two main understorey trees, Myrsine kermadecensis Chessem. and Ascarina lucida var. lanceolata (Hook. f.). Allan (Sykes 1969). These species were probably more common in 1966-67 than previously and were found to form dense pure stands in the dry and wet forests (respectively). The fern Pteris comans, also reportedly unpalatable to the goats, was also thought to be more common on the island due to its selective advantage (Sykes 1969).
Interaction with other invasive species: The introduced terrestrial aroid Alocasia macrorrhiza (L.) Schott., is unpalatable to the goats, a trait which is thought to have given it a selective advantage on the island, allowing it increase markedly in number to dominate large areas of the forest (Sykes 1969). This large-leaved plant restricts light reaching the forest floor and inhibits the regeneration of woody species. In addition to Alocasia a number of other introduced plants increased at the expense of indigenous flora due to their unpalatability to goats (Sykes 1969).
Modification of successional patterns: The forests of Raoul Island are mainly dominated by the Kermadec pohutukawa (Metrosideros kermadecensis W.R.B. Oliver) (Sykes 1969). Sykes (1969) reported that this is a favoured species by goats and in most areas observed on the island (before goat control) little or no young seedlings of this species were observed. As this is the main canopy tree, its disappearance over large parts of the island would obviously have resulted in drastic changes to the rest of the vegetation as well. (A similar effect to this has been realised on Cuvier Island near the New Zealand coast). The Raoul forests are noted also for their large tree ferns (belonging to two endemic species of Cyathea). Sykes (1969) hypothesised that these had became notably less common because of the inhibition of regeneration by the goats. Seedlings of the endemic Coprosma acutifolia Hook. F. were also reported to be reduced by the goats; the plant is a principal component of the understorey layer in dry forests and the canopy in wet forests (Sykes 1969).
Reduction in native biodiversity: The destruction of indigenous flora by goats was noted in 1908 (Oliver 1910, in Parkes 1984). A botanical survey conducted in 1966/67 and reported by Sykes (1969) revealed that at least one endemic species, Hebe breviracemosa, which is very palatable to goats, was nearly extinct. The survey also made light of the following points. Homalanthus polyandrous, Boehmeria dealbata and Pseudopanax kermadecense were reported to be uncommon due to the browsing activity of the goats. Whilst the mature trees were relatively unaffected, the regeneration of these species appeared to be inhibited. Regeneration of the endemic Kermadec nikau, Rhopalostylis cheesmanii, wharangi, Melicope ternate and karaka, Corynocarpus laevigatus has also probably been kept in check by goat browsing. Other palatable species, such as the karo (Pittosporum crassifolium) and the endemic Kermadec taupata (Coprosma petiolata), were mainly confined to the cliff faces. The Kermadec ngaio, once a characteristic of the coastal scrub, had also been greatly reduced in many parts of Raoul Island. Olivier (1910) noted that goats barked parapara trees (Heimerliodendron brunonianum) and they seemed to be nearly extinct by 1967. Goats have also been known to climb Kermadec pohutukawa and mahoe Melicytus ramiflorus to browse epiphytic ferns (particularly Asplenium). The ice plant Disphyma australe, abundant on the coast, was also browsed by the goats. Egmont National Park (New Zealand)
Reduction in native biodiversity: By the 1920s the impact of goat browsing on local and indigenous vegetation on Mt Taranaki began to be noted (Thomson 1922, in Parkes 1990). Cuvier Is. (New Zealand)
Herbivory: Goats have been recognised as “the single most destructive herbivore” introduced to the islands of the world (King 1985). By eating young trees in a forest they prevent the replacement of adult trees that form the forest canopy.
Reduction in native biodiversity: Atkinson (1960) reported on the devastating effect that browsing goats had inflicted upon the vegetation of Cuvier Island. The forest was originally dominated by the New Zealand pohutukawa Metrosideros excelsa Gaertn. However, the regeneration of this and other tree species has been completely halted, and on the seaward slopes there was little of this original woody vegetation left (Sykes 1969).
A 36-year study of forest recovery since the eradication of goats showed that more than two-thirds of the tree and shrub species present had been reduced by goats, some to very low numbers. At least six other plant species on the island had probably been eliminated by goats (Atkinson, in prep.). In addition, early indications are that at least six plant species became extinct on the island as a result of goats Agrigan (Aguigan, Aguijan) Is. (Northern Mariana Islands)
Herbivory: Goats exterminated much of the original vegetation in early 1940s (DiSalvatore 1981). Pitcairn
Herbivory: Serious soil erosion follows the deforestation caused by the goats (Moverly 1953: 65) Pitcairn
Habitat alteration: Deforestation, leading to soil erosion (Moverly 1953, in Varnham 2005). Pitcairn
Habitat alteration: Capra hircus causes deforestation, leading to soil erosion (Moverly, 1953 in Varnham, 2006) La Palma Is. (Spain)
Habitat alteration: The Endangered (EN) Col de Risco (Crambe microcarpa) is endemic to the island of La Palma, Canary Islands, Spain. The major threat to the survival of this species is browzing and trampling by goats (Capra hircus) and the introduced game species aoudad (Ammotragus lervia) leading to decline in population and habitat destruction (Guerra 2011).
Predation: Endemic to the island of La Palma, the Canary Islands, Spain, Centaurea (Cheirolophus santos-abreui) is listed as Critically Endangered (CR) in the IUCN Red List of Threatened Species. The main threats to the survival of this species is browzing/herbivory and trampling by feral goats and introduced game species aoudad (Ammotragus lervia) leading to decline in populations and habitat destruction. Other threats include competition with the invasive alien plant (Ageratina adenophora) and seed predation by the animal parasite (Chaetorellia sp.) (Cáceres et al 2011).
Predation: Native to the Canary Islands and found on La Palma and Tenerife, Garbancera canaria (Cicer canariense) is listed as Endangered (EN) in the IUCN Red List of Threatened Species. The main threats to the survival of this species is the threat posed by introduced herbivores such as rabbits (Oryctolagus cuniculus), goats, sheep (Ovis aries); and the game species Ovis musimom and aoudad (Ammotragus lervia) (Guerra & Betancort 2011).
Predation: The Endangered (EN) Col de Risco (Crambe microcarpa) is endemic to the island of La Palma, Canary Islands, Spain. The major threat to the survival of this species is browzing and trampling by goats and the introduced game species aoudad (Ammotragus lervia) leading to decline in population and habitat destruction (Guerra 2011).
Predation: The Vulnerable (VU) Retamón (Genista benehoavensis) is endemic to the island of La Palma, Canary Islands, Spain. The major threat to the survival of this species is predation by goats; rabbits (Oryctolagus cuniculus) and the introduced aoudad (Ammotragus lervia) (Alamo et al 2011)
Predation: The La Palma endemic (Lactuca palmensis) is listed as Least Concern (LC) in the IUCN Red List of Threatened Species. Threats to this species include predation by feral goats, rabbits (Oryctolagus cuniculus) and the introduced game species aoudad (Ammotragus lervia) (Guerra 2011) Tenerife (Spain)
Predation: Native to the Canary Islands and found on La Palma and Tenerife, Garbancera canaria (Cicer canariense) is listed as Endangered (EN) in the IUCN Red List of Threatened Species. The main threats to the survival of this species is the threat posed by introduced herbivores such as rabbits (Oryctolagus cuniculus); goats (Capra hircus); sheep (Ovis aries); and the game species Ovis musimom and aoudad (Ammotragus lervia) (Guerra & Betancort 2011). Canarias (Spain)
Predation: Endemic to the island of La Palma, the Canary Islands, Spain, Centaurea (Cheirolophus santos-abreui) is listed as Critically Endangered (CR) in the IUCN Red List of Threatened Species. The main threats to the survival of this species is browzing/herbivory and trampling by feral goats and introduced game species aoudad (Ammotragus lervia) leading to decline in populations and habitat destruction. Other threats include competition with the invasive alien plant (Ageratina adenophora) and seed predation by the animal parasite (Chaetorellia sp.) (Cáceres et al 2011).
Predation: Native to the Canary Islands and found on La Palma and Tenerife, Garbancera canaria (Cicer canariense) is listed as Endangered (EN) in the IUCN Red List of Threatened Species. The main threats to the survival of this species is the threat posed by introduced herbivores such as rabbits (Oryctolagus cuniculus); goats; sheep (Ovis aries); and the game species Ovis musimom and aoudad (Ammotragus lervia) (Guerra & Betancort 2011). Cotton Cay (Turks and Caicos Islands)
Threat to endangered species: Capra hircus pose a serious threat to the the native 'Critically Endangered (CR)' Turks & Caicos rock iguana (see Cyclura carinata in IUCN Red List of Threatened Species), presumably through competition for food plants, altering the vegetational composition of habitats and trampling soft substrates where iguanas burrow or nest (Alberts, 2000 in Varnham, 2006; Mitchell et al., 2002 in Varnham, 2006). Turks and Caicos Islands
Threat to endangered species: Capra hircus pose a serious threat to the the native 'Critically Endangered (CR)' Turks & Caicos rock iguana (see Cyclura carinata in IUCN Red List of Threatened Species), presumably through competition for food plants, altering the vegetational composition of habitats and trampling soft substrates where iguanas burrow or nest (Alberts, 2000 in Varnham, 2006; Mitchell et al., 2002 in Varnham, 2006). Hawaii (Hawai‘i) Is. (United States (USA))
Herbivory: Goats have been recognised as “the single most destructive herbivore” introduced to the islands of the world (King 1985). By eating young trees in a forest they prevent the replacement of adult trees that form the forest canopy.
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