Saint Helena

There is no specific legislation relating to invasive species although there are controls on plant, livestock and honeybee imports aimed at preventing the introduction of pest and pathogens. In addition the Endangered Species Ordinance does give the Governor in Council the power to prohibit the growing or cultivation of any plant or the keeping of any animal if it is liable to damage the welfare or continued existence of any plant or animal.

The JNCC database lists 415 introduced species for Saint Helena. This includes 291 plants, 105 invertebrates and 19 vertebrates.

Problems with invasive non-native species

Overall, non-native species are well recorded on Saint Helena. Invasive plant species dominate Saint Helena’s flora. Examples include New Zealand Flax (Phormium tenax) and the Quinine Tree (Cinchona succiruba) which are responsible for the destruction of areas of native fern thicket; Thorn Apple (Datura stramonium) which is a serious weed; Bull Grass (Juncus tenuis) is regarded as reducing the suitability of Wirebird nesting sites.

There is a large range of introduced plant pests, some of which cause significant damage to agricultural and horticultural crops (eg (Brevicoryne brassicae) a cabbage aphid, Cottony Cushion Scale (Icerya purchasi), a tortricid moth (Cryptophlebia leucotreta), Diamond Back Moth (Plutella xylostella)). A scale insect (Orthizia insignis) is decimating the last surviving stands of native gumwood trees (Commidendrum spp).

Mynah Birds (Acridotheres tristis) take the eggs and hatchlings of Wirebirds, depredate fruit trees and other crops and are implicated in the spread of seeds from exotic plant species. Cats (Felis catus) are regarded as being largely responsible for the demise of Saint Helena’s historic seabird colonies. House mice (Mus musculus) may raid Wirebird nests and are implicated in the decline of endemic snails and other invertebrates. Rabbits (Orytolagus cuniculus) and sheep (Ovis aries) can seriously damage native vegetation.

Priority invasive non-native species and actions

Flax clearance and tree fern thicket restoration has occurred at High Peak and Diana’s Peak.
There are a number of successful biological control programmes against plant pests (eg (Icerya purchasi) control by a ladybird beetle (Radolia cardinalis); (Orthyzia insignis) control by a predatory Coccinellid beetle; (Plutella xylostella) by several biological agents).

Goats, which have significantly modified the landscape in the past were removed from the island in the 1960s. An eradication campaign against feral Donkeys (Equus asinus) has been largely successful. Shooting campaigns against dogs (Canus familiaris) and trapping of cats have largely reduced their feral populations in recent years. Poisoning campaigns against both species of rats were carried out in urban areas in the 1990s and there is ongoing action against them in rural areas.

Thin strip of image show tree trunk and bark