Caroline Island - Flora and Fauna

Flora and Fauna

Despite more than three centuries of occasional human impact on Caroline, it is considered to be one of very few remaining "near-pristine tropical islands." and has been rated as one of the most unspoiled Pacific atolls. Its relatively undisturbed state has led to Caroline being considered for designation as a World Heritage Site and as a Biosphere Reserve. Ecological surveys documenting the island's flora and fauna have been made intermittently through the later 20th century: Caroline was visited in 1965 by the Pacific Ocean Biological Survey Program, in 1974 by the Line Island Expedition, and in 1988 and 1991 by the United Nations Environment Programme Wildlife Conservation Unit.

Caroline Island is heavily vegetated, and most islets possess three ringed zones of vegetation: an outermost herb mat, typically composed mainly of Heliotropium anomalum; an inward zone of shrub, primarily Heliotropium foertherianum; and a central forested region, typically dominated by groves of Pisonia grandis trees. Coconut palms have also been introduced and exist in substantial quantities on the larger islets. This pattern of vegetation is consistent across the larger islets, with smaller islets lacking the central forest and the smallest vegetated solely by low herbs. Other common plants include Suriana maritima and Morinda citrifolia.

Caroline Island is an important breeding site for a number of species of seabirds, most notably the Sooty Tern (Onychoprion fuscata), numbering around 500,000 – a colony of Sooty Terns dominates the eastern islets – and the Great Frigatebird (Fregata minor), numbering over 10,000. Caroline Island and its neighbor, Flint Island, also host some of the world's largest populations of the coconut crab. (Birgus latro). Other native animals include the Tridacna clam, which is abundant in the central lagoon, hermit crabs, and multiple species of lizards.

The endangered green turtle (Chelonia mydas) nests on the beaches of Caroline Island, but there have been reports of poaching by recent homesteaders. The Bristle-thighed Curlew (Numenius tahitiensis), a migrant visitor from Alaska, is also classified as vulnerable.

Around twenty non-native species of flora have been introduced to Caroline Island via human contact. Among these are the vine Ipomoea violacea, which has begun to proliferate. Domestic cats and dogs introduced alongside a small homestead have driven the seabird population away from the islet of Monu Ata-Ata.