The introduction of non-native species is regarded by IUCN-The World Conservation Union as the second most-important threat to biodiversity after habitat loss (Vermeulen and Whitten 1999). Many species of plants and animals have been brought both intentionally and unintentionally to Jamaica by humans, who have also created the conditions that facilitate the spread of non-native species. While many imported species [which intriguingly includes camels, sloths, and bears (Browne 1789)] remained innocuously confined or failed to become established following their release or escape, a number have had devastating effects.
Pest species, (for table) which invade disturbed land and halt the regeneration of forest, include ferns such as Gleichenia sp., Dichranopteris sp. Nephrolepis multiflora (sword fern) and Thelypteris opulenta. The red bead tree (Adenanthera pavonina) can become established on hills and forms monocultural stands in some places while bamboo (Bambusa vulgaris) takes over abandoned cockpit bottoms. Roseapple trees (Syzgium jambos), an introduced species which is native to Asia, are spreading through the Cockpit Country and may be displacing native species, although they seldom form single species stands. The development of practical ways to control invasive species, particularly ferns on hilltops denuded by cultivation and fire, could be one of the most important single contributions to conservation of the Cockpit Country.
See also the Website of the Jamaican Clearing House Mechanism
Some were brought to Jamaica as domesticated animals (e.g., dogs, cats, goat, cattle). Others were released as pest control agents (e.g., Marine toads (Bufo marinus) in 1844, Indian mongoose (Herpestes auropunctatus) in 1872; both to control rats) or represent the organisms associated with human colonization (e.g., rats [Rattus spp.]). The mongoose has been linked with either the proximate or ultimate cause of extinction in five endemic invertebrates: one lizard -- Giant galliwasp (Celestrus occiduus), one snake -- Black racer (Alsophis ater), two birds -- Jamaican Poor-will (Siphonorhis americanus) and Jamaican Petrel (Pterodroma caribbaea), and one rodent -- Jamaican rice rat (Oryzomys antillurum).
While not encountered as frequently as in dry coastal habitats, the mongoose occurs along the periphery of the Cockpit Country and has been observed by S. Koenig one kilometer into the interior from Windsor. Marine toads, opportunistic and highly mobile, are common along the periphery of the Cockpit Country where the moist conditions prevent dessication, a major mortality factor for this species elsewhere in the tropics (Zug 1983). Eleutherodactylus johnstonei was introduced about 1890 and rapidly expanded throughout disturbed habitats of central Jamaica. It is found along the periphery and cleared roads of the Cockpit Country. There is concern that females of the endemic E. junori may be unable to locate calling males because of the much louder calls of the larger E. johnstonei (Johnson 1988). No systematic searches have been conducted to determine the extent to which these species penetrate the interior forest.
The Shiny Cowbird (Molothrus bonariensis) has been expanding its range naturally from South America over the last 100 years. It was first observed in the wild in Jamaica about 10 years ago. It is a brood parasite, laying its eggs in the nests of host species that lack evolved mechanisms to detect and eject foreign eggs. The Cowbird has caused major declines of several host species on other Caribbean islands. The Jamaican Blackbird and the Jamaican Oriole (Icterus leucopteryx) are recognized as particularly vulnerable because of their close taxonomic relationship, although the Jamaican Blackbird's habitat requirements may not overlap significantly with habitat utilized by cowbirds. Other threatened species include flycatchers, vireos, and warblers. The Shiny Cowbird has not been recorded in the Cockpit Country but it does occur in the Upper Black River Morass, particularly in disturbed areas of livestock production. Its effects on native land birds have never been studied in Jamaica.
Pathogens and parasites
The role of pathogens and parasites is gaining increasing recognition as a significant limiting factor in species conservation efforts, particularly for island flora and fauna that have typically evolved in the absence of disease vectors (Warner 1968, Cooper 1989, Snyder et al. 1994, Gulland 1995; see also MacPhee and Marx 1997). The contribution of diseases and insect pests to patterns of extinction of plants and animals has not been assessed in Jamaica. Only when pests have widespread impacts on commercial species are their effects studied (e.g. pink mealey bug in the eastern Caribbean). Research is needed to document presence and prevalence of pathogens and parasites, particularly for species taxonomically-related to imported species.
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