The main part of this EBA is formed by Puerto Rico and its offshore islands (e.g. Mona, Vieques, Culebra) which are a self-governing commonwealth in association with the USA. The land is mountainous and was originally almost completely forested. Because of variations in climate, topography and soils, the forests are diverse and include mangroves, wet and dry coastal forest, wet and dry limestone forest in the west, rain forest in the Cordillera Central and Sierra de Luquillo, and elfin forest on a few summits.

The Virgin Islands comprise two dependent territories, of the UK (main islands Anegada, Tortola and Virgin Gorda) and USA (St Thomas, St John and St Croix), and consists of c.100 small islands and cays with dry scrub forest, mostly heavily modified by man.

Nearly all the restricted-range species are forest birds, present in a variety of forest types and man-modified habitats, with the exception of Amazona vittata (now confined to rain forest), Caprimulgus noctitherus (dry limestone forest) and Dendroica angelae (upper montane and elfin forest). All species occur on Puerto Rico apart from Loxigilla noctis, which, in this EBA, is only found on St John in the US Virgin Islands. Three species are confined to Puerto Rico and the Virgin Islands: Otus nudipes, Melanerpes portoricensis (now extinct on St Thomas) and Myiarchus antillarum. Five further species occur on Puerto Rico and the Virgin Islands and elsewhere: Geotrygon mystacea, Anthracothorax dominicus, Eulampis holosericeus, Orthorhyncus cristatus and Margarops fuscatus. Many restricted-range species are shared with Hispaniola (EBA 028) to the west and the Lesser Antilles (EBA 030) to the east.

Hispaniolan Parrot Amazona ventralis, a restricted-range species from Hispaniola (EBA 028), and Green-checked Amazon A. viridigenalis, a restricted-range species from Mexico (EBA 011), have been introduced to Puerto Rico, but this is outside their natural historical range so they have not been included as restricted-range species of this EBA.

Natural succession has been slowly reforesting Puerto Rico since industry replaced agriculture as the economic base in the late 1940s (Wadsworth 1950, Birdsey and Weaver 1982). Data from 1978 indicated 37% of the island to be covered in woody vegetation, but this comprised 32% secondary growth, 5% native trees used for shade in coffee plantations and less than 1% virgin forest (Harcourt and Sayer 1996). Secondary forest is used by some restricted-range birds, and coffee plantations in the central mountains provide an important refuge for some species (Brash 1987), but hurricanes are a continual threat to small remnant populations (Wiley 1985).

Storms may, however, have positive long-term effects. Thus, because of deforestation, hunting and nest-robbing, Amazona vittata had a population of just 13 in the early 1970s, confined to the Luquillo mountains; but the mountain forests (which are older, undisturbed and not highly productive) may not be optimal habitat. Hurricane damage in 1989 reduced parrot numbers by half but may have stimulated production of buds, fruit and seeds, resulting in increased clutch sizes and numbers of nests of the survivors, as well as forcing them to disperse to the lowlands, which may have led them to discover new nesting sites (Meyers et al. 1993). These effects - along with a conservation programme, involving artificial nest-sites, control of predators and competitors, and captive breeding - probably helped the parrot's recovery to c.40 birds by 1996.

Two further restricted-range species are judged to be threatened: Caprimulgus noctitherus is at risk from loss of its specialized habitat (c.100 km²) and from introduced predators such as mongooses, rats and cats, while Agelaius xanthomus is under pressure from a range of threats, most notably brood-parasitism by Shiny Cowbirds Molothrus bonariensis, loss of mangroves and introduced predators - although the Mona Island population is reasonably healthy and not threatened by cowbirds (J. M. Wunderle in litt. 1996). A population decline has recently been noted in Vireo latimeri in Guánica Forest, also attributable to parasitism by M. bonariensis (Faaborg et al. 1997).

Widespread threatened species which occur in this EBA include West Indian Whistling-duck Dendrocygna arborea (Vulnerable), Piping Plover Charadrius melodus (Vulnerable, winter only), Plain Pigeon Columba inornata (Endangered) and Red Siskin Carduelis cucullata (Endangered, the population here derived from escaped cage-birds).

Forest is present in over 20 protected areas on Puerto Rico including two Biosphere Reserves: the Luquillo Forest (rain forest, also known as the Caribbean National Forest, 113 km²) in the north-east and the Guánica State Forest (dry limestone forest, 40 km²) in the south-west. Private lands also contain large, mature tracts of secondary forest.

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Puerto Rico and the Virgin Islands. Downloaded from https://datazone.birdlife.org/eba/factsheet/25 on 23/11/2024.