Crabs are the most conspicuous and probably the most numerous inhabitants of the forest floor and beach fringe. The little nipper (Geograpsus grayi) is common under the Pisonia forest. The robber crab (Birgus latro) is occasionally observed within the forest but was more abundant prior to harvesting by Cocos-Malays.
Three species of hermit crabs are present in large numbers - the red hermit crab (Coenobita perlata) the purple hermit crab (C. brevimana) and the tawny hermit crab (C. rugosa). The land crab (Cardisoma carnifex) is abundant, particularly in the saltmarsh and on the fringes of the lagoon. Yellow nippers (Geograpsus crinipes) and the red crab (Gecarcoidea natalis) also occur. The horn-eyed ghost crab (Ocypode ceratophthalma) is commonly found on the north-western beaches with grapsus (Grapsus tenuicrustatis) common on rock sections of the coast.
A species of cricket Ornebius sp., occurs among the leaves of both cordia and pisonia, and Nerius lineolatus, a long-legged dipteran, and the mosquito (Aedes albopictus) are plentiful. Butterflies, ants, cockroaches, beetles and weevils are also represented. Spiders, a small wood-louse, various species of ectoparasitic ticks and mites, scorpions, termites, a centipede and a terrestrial mollusc (Melampus sp.) have been recorded but as yet no millipedes or earthworms have been found.
Pulu Keeling National Park has 24 listed species of birds with eight being of special conservation significance. When Charles Darwin visited the Cocos (Keeling) Islands in April 1836, the "immense number" of marine birds recorded in 1828-29 on the main atoll (cited Gibson-Hill 1949) were probably still present though somewhat diminished. The reason for the decline in birds of the main atoll was almost certainly due to habitat change, intense hunting by people and predation by cats and rats.
Fourteen species recorded from North Keeling Island are listed for protection under the Japan-Australia, China-Australia and the Republic of Korea-Australia Migratory Birds Agreements (JAMBA, CAMBA and ROKAMBA). The island is the focus of seabirds over a huge expanse of the central-eastern Indian Ocean, is one of the few remaining pristine tropical islands in the Indian Ocean and is of unique importance to the ocean's seabird biota.
Find out more about birdlife on the Cocos (Keeling) Islands - download Island Explorer's bird brochure.
Red-footed Booby Sula sula
By far the most numerous seabird on North Keeling Island the red-footed booby has an estimated population of around 30,000 breeding pairs, making it one of the most important colonies of red-footed boobies in the world.
The red-footed booby is the smallest of all boobies at about 70 centimetres in length and with a wingspan of up to one metre. It has red legs, and its bill and throat pouch are coloured pink and blue.
Greater and lesser frigatebirds Fregata minor and F. ariel
The great frigatebird is a lightly built large seabird up to 105 cm long with predominantly black plumage. The female is larger than the male and has a white throat and breast, and the male's scapular feathers have a purple-green sheen. In the breeding season, the male is able to distend a striking red gular sac. Both lesser and great frigate birds, occur on the island in large numbers. This population of lesser frigate birds is the second largest in Australia and in the Indian Ocean.
Cocos buff-banded rail Rallus phillipensis andrewsi
The Cocos buff-banded railis significant as the only endemic bird in the island group. It is a common bird on North Keeling Island and occurs in all habitats. The largely terrestrial bird is about size of a small domestic chicken. It frequently forages along the lagoon shore, apparently eating crustacea which are abundant in the seagrass deposited along the tide line. The rail is now probably extinct on the southern atoll, due largely to habitat destruction. The population on North Keeling Island is around 750-1000 individuals, and the species is listed as endangered.
White-tailed tropicbirds Phaethon lepturus
White-tailed tropicbirds are a common sight in the skies above North Keeling Island spiralling upwards in the thermal eddies. They nest in moderate numbers in hollows of mature pisonia and cordia trees.
The adult white-tailed tropicbird is a slender, mainly white bird, 71-80 cm long including the very long central tail feathers, which double its total length.
The mourning gecko or common smooth-scaled gecko Lepidodactylus lugubris is common in the park. This small (10.5 cm total length), nocturnal gecko feeds on small insects and flower nectar. This species is notable because it is its ability to reproduce asexually. Females engage in pseudo-copulation, stimulating both to produce viable eggs.
Nesting green turtles (Chelonia mydas) nest on the island and hawksbill turtles (Eretmochelys imbricata) inhabit the waters of the park. The only species of sea snake recorded from the southern atoll is the yellow-bellied sea-snake (Pelamis platurus).