Jamaica is believed to be the product of prehistoric volcanoes. The central ridge of the Blue and John Crow Mountains range comprises metamorphic rock that has pushed through surrounding limestone during the land ascent from the sea floor. As the island of Jamaica evolved, deep basins formed between the Cretaceous rock of the Blue Mountain range and the limestone plateau in the west. The rock formations visible in the range and surrounding areas are a combination of conglomerates, sandstone and shale.
A unique feature of the Blue and John Crow Mountains is the Cloud Forest – a rare habitat of tropical mountains – making up only 1.2% of all tropical forests in the Americas and 2.5% of tropical forests globally. In Jamaica, montane cloud forests are found only in the Blue Mountains. Occurring at elevations 1,000 metres and higher, they are unique to the Caribbean. Cloud forests of similar elevation (for example in Hispaniola and Cuba) feature coniferous trees, but the Blue and John Crow Mountains is dominated by broadleaf trees with only two native conifers e.g. Juniper Cedar (Juniperus lucayana) and Mountain Yacca (Podocarpus urbanii).
Jamaica’s Blue and John Crow Mountains sustain biodiversity of global significance. It is among the Caribbean’s 290 Key Biodiversity Areas and the Caribbean’s 48 Wholly Irreplaceable Sites. The National Park is also on the International Union for Conservation of Nature and World Wildlife Fund list of 200 globally important sites for the conservation of plant biological diversity and is noted as an irreplaceable protected area for the conservation of the world’s amphibian, bird and mammal species.
Over half the flowering plants in the national park are found only in Jamaica and about one third are endemic to the national park. At least 40% of the higher plants (flowering and non-flowering) are also endemic to Jamaica. The forest is made up of large trees such as Juniper Cedar (Juniperus lucayana), Blue Mahoe (Hibiscus elatus) and Soapwood (Clethra occidentalis) and smaller shrubs such as Hot-lips (Cephaelis elata) and Jamaican Rose (Blakea trinervia). To capture sunlight in the thick forest, many plants climb up the trees, like Climbing Bamboo (Chusquea altifolia) whilst others spend all their lives on the branches of trees, like orchids and bromeliads. Tree ferns and other plants that like a lot of water are common in the Blue and John Crow Mountains.
The trunks and branches of the trees are covered with a wide variety of other plants such as lichens (a combination of algae and fungi) which are usually grey-ish green and are either flat against the tree (or even on rocks) or hang from tree branches like Old Man’s Beard.
For most Jamaican land animals, the Blue and John Crow Mountains National Park is their last refuge - a large area of natural forest where they are protected from human disturbance. The region is one of two known habitats of the Giant Swallowtail Butterfly (Pterourus/Papilio homerus) – the largest butterfly in the Western Hemisphere. The Cockpit Country is the other location.
To support the population of this endangered butterfly species, the Jamaica Conservation and Development Trust has worked with members of the Bowden Pen Farmers’ Association, which is based near the habitat of the Giant Swallowtail, to establish a plant nursery that grows the Water Mahoe (Hernandia catalpifolia). This plant is the only source of food for the Homerus butterfly caterpillars. The seedlings have been used to reforest several degraded areas, and this has likely contributed to the increasing numbers of the butterflies seen in the area.
The national park is one of the largest bird migratory sites in the Caribbean. Along with Jamaica’s endemic birds, it hosts over 200 bird species throughout the year; making it a great location for bird-watching. It is the only place on the island where all Jamaica’s unique birds can be observed, including the endangered Jamaican Blackbird (Nesopsar nigerrimus). Other highlights for bird enthusiasts include: Rufous-throated Solitaire (Myadestes genibarbis) Mountain Witch (Geotrygon versicolor); and the Jamaican Tody or Robin Redbreast (Todus todus).
While there are no large or poisonous animals in the Blue and John Crow Mountains National Park, it is home to four of Jamaica’s six endemic snakes. The Jamaica Boa (Epicrates subflavus) is the largest and can grow up to 2 metres (6 feet).
The national park is a major habitat for Jamaica’s amphibian population; the other being the Cockpit Country. The region supports 11 of the 23 species of endemic frogs; five of which are only found in the Blue and John Crow Mountains National Park.
The Blue and John Crow Mountains is also the habitat of the Jamaican coney (Geocapromys brownii). Once though to be extinct, the rodent is the largest endemic animal on the island.