Location and General Description
This ecoregion is distributed among the Cayman Islands, specifically areas on Grand Cayman Island, Little Cayman Island, and all of Cayman Brac Island. The three Cayman Islands are located at the western end of the Greater Antilles in the Caribbean. Their combined land area is 259 km2. Most of the population of the Caymans lives on Grand Cayman where development typical to the Caribbean has rapidly altered the island’s environment. All three Cayman Islands are flat limestone with low elevation. The human populations of the three islands differ considerably with fewer than 100 on Little Cayman and less than 2,000 on Cayman Brac. This is reflected in the varying degrees to which the islands' environments have been changed. Little Cayman is the least disturbed of the group, with almost all of the interior untouched as of 1980 (Diamond 1980). In contrast, the rapid development of Grand Cayman has resulted in degradation and alteration of most of the natural habitats. Clearing of natural woodland and thicket for roads, housing, tourism and agriculture continue to be the most significant pressures on this ecoregion.
The dry woodlands of Grand Cayman and Cayman Brac have suffered a long history of disturbance and timber extraction (IUCN 1992). The tropical hardwoods of this ecoregion regenerate and grow very slowly. Consequently, the effects of logging early in this century are clearly visible. In central and eastern Grand Cayman and on Cayman Brac, the woodlands form a complex mosaic of secondary growth at various stages. Primary vegetation is restricted to the most inaccessible areas. Little Cayman is still dominated by primary vegetation (Burton 1992). The low elevation dry woodlands on all three islands of the Caymans are of regional importance for biodiversity conservation (Procter & Fleming 1999).
The flora of the Cayman Islands includes 20 species of orchids, of which five are endemic. All orchids and cacti of the Caymans are included in Appendix II of CITES (Procter & Fleming 1999). Twenty-one taxa of reptiles and amphibians in the Cayman Islands are considered endemic. Notable of these are three subspecies of iguana (Cyclura nubila), numerous anoles (Anolis spp.), and several subspecies of the Cayman islands dwarf boa (Trophidopsis caymensis). The status of the lizard Leiocephalus carinatus is indicative of many endemic species found among these islands. This species was previously widespread on surrounding coastal areas but many colonies are thought to be extirpated because of beachfront development (Procter & Fleming 1999).
A field guide to the 181 bird species of the Caymans was published by Bradley (1985) and an overview of the avifauna is provided by Bradley (1994). There are 21 families of breeding birds represented by 38 genera and 46 species in the Cayman Islands, 17 subspecies that are endemic (Bradley 1994). The Cayman Brac Parrot (Amazona leucocephala hesterna) is common in the Cayman islands, but is at risk due to habitat destruction by humans and hurricanes and by harvesting for pets. Overall, the species has declined dramatically throughout its range and is considered threatened (Raffaele et al. 1998). The proximity of Little Cayman and Cayman Brac has meant that some endemic subspecies are shared by both islands. The only non-domestic mammals found in the Cayman Islands are bats. Eight species are noted of which none is endemic.
The National Trust for the Cayman Islands Law established the National Trust to preserve the historic, natural, and maritime heritage of the islands. The National Trust is a statutory, non-governmental organization involved with land acquisition, management for conservation purposes, and maintaining areas of land for wildlife conservation. The Trust is also joint proprietor of a 24 ha botanical garden on Grand Cayman with woodlands being preserved in their natural state. In1990, responsibility for all environmental matters was placed in the Portfolio for Education, Environment, Recreation and Culture. The Natural Resources Unit, a department under the Portfolio, is responsible for the day-to-day management of the natural environment.
The eight Protected Areas in the Cayman Islands cover just over 8,000 ha, equivalent to 31% of the islands’ land area. In 1989 the government gave 257 ha of land (Salina Reserve) to the National Trust. In December 1991 ownership of a 40 ha woodland site on Cayman Brac, important as a nesting area for the Cayman Brac Parrot (Amazona leucocephala hesterna), was transferred to the National Trust by The Nature Conservancy (USA) and is now titled Brac Parrot Reserve (IUCN 1992).
Types and Severity of Threats
Development pressures on Grand Cayman and Cayman Brac continue to be the main threat to biodiversity in the Cayman Islands. Little Cayman with a population of less than 100, has until recently remained relatively undisturbed. However, the number of buildings has doubled in just the past few years (Procter & Fleming 1999). The dry tropical forests of this ecoregion support a large fraction of the human population and as a result are under intense pressure. The result is that the tropical dry forests not only provide space for the expanding human population but also are used intensively as a source of fuelwood and charcoal. Grazing animals also are often allowed to roam through dry forests (Alberts 1999).
Justification of Ecoregion Delineation
The Cayman Islands were divided into dry forest and xeric scrub ecoregion, which were then distinguished from the mangroves. The lines to delineate the dry forests were derived from both the Department of Tourism map (1989) which distinguished between woodlands and open areas of low growth, and the Stoddard map (1988) which distinguishes mangrove and swamp habitat from terrestrial habitat. The lines for the potential dry forest ecoregion were made to encompass woodlands but exclude mangroves.
Alberts, A. (comp. & ed.). 1999. West Indian iguanas: status survey and conservation action plan. IUCN/SSC West Indian Iguana Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK.
Bradley, P. 1985. Birds of the Cayman Islands. Cayman, Bradley, Private Collection.
Bradley, P. B. 1994. In: The Cayman Islands: Natural history and biogeography. Brunt, M. A. and J. E. Davies, editors, Kluwer Academic Publishers. Dordrecht. pp. 377-406.
Burton, F. J. 1992. A strategy for the establishment of terrestrial reserves in the Cayman Islands, with special reference to a new reserve on Grand Cayman. Cayman, The National Trust for the Cayman Islands.
Department of Tourism, Cayman Islands. 1989. Visitors Map: Cayman Islands. Map 1:50,000. Cayman Islands Government & Ordnance Survey, Southampton, England.
Diamond, A. W. 1980. Ecology and species turnover of the birds of Little Cayman. Atoll Research Bulletin. 241: 141-164.
IUCN. 1992. Protected areas of the world: a review of national systems. Volume 4: Nearctic and Neotropical. IUCN, Gland, Switzerland and Cambridge, UK.
Procter, D., and L. V. Fleming, editors. 1999. Biodiversity: The UK overseas territories. Joint Nature Conservation Committee, Peterborough.
Raffaele, H., J. Wiley, O. Garrido, A. Keith, and J. Raffaele. 1998. A guide to the birds of the West Indies. Princeton University Press. Princeton.
Stoddart, D.R., M.A. Brunt, and J.A. Davies, editors. 1988. The biogeography and ecology of the Cayman Islands. W. Junk Publishers, Dordecht, The Netherlands. Maps 1:25,000 included.
Prepared by: Sean Armstrong
Reviewed by: In process