Protected Areas and World Heritage Programme

NAME Kiritimati (Christmas) Island Wildlife Sanctuary

LOCATION 2^o00'N, 157^o20'W; in the northern Line Islands, 285 km southwest of Tabuaeran, 2,500 km south of Honolulu in Hawaii and 2,700 km north of Tahiti in French Polynesia.

AREA Island 32,137 ha; main lagoon 16,000 ha; subsidiary lagoons 16,800 ha.

ALTITUDE Sea level to 13 m.

OVERVIEW Kiritimati is the world's largest coral atoll with a total land area of 321 sq.km and an approximately equal area of lagoons. With its multi-complex system of subsidiary land-locked lagoons, the island and its several hundred islets harbour some of the world's largest concentrations of seabirds, and are of global significance both in terms of diversity and abundance. The entire island is a Wildlife Sanctuary within which there are five closed areas.

PHYSICAL FEATURES Kiritimati has the largest land area of any coral atoll in the world, with an approximately equal area of saltwater and supersaline lagoons. The single, large, flat island consists of coral formations 30-120 m in depth overlying volcanic rocks, and has a large tidal lagoon covering 16,000 ha and opening to the northwest. At the eastern end of this lagoon, there are several hundred smaller landlocked lagoons occupying 16,800 ha and delimited by causeways and larger tracts of land. Salinities vary widely, and many of the lagoons are supersaline. These tidal and landlocked lagoons contain hundreds of islets, the three principal ones being Cook Island, Motu Tabu and Motu Upoa. There are considerable variations in water level, and extensive intertidal mudflats are present. Freshwater lenses occur, with salinities varying between 0 and 3.5 p.p.t., and with a water table generally at a depth of between 0 and 2 m. Thirteen different physical units have been described by Garnett (1983), namely seaward reef, seaward beach, beach crest, coastal dunes, boulder ramparts, coastal plain, central ridge, inland dunes, lagoon scarp, lagoon dunes, lagoon flats, lagoon beach and lagoon reef. The island rises to 13 m in height at the top of the dunes along the north coast of the Southeast Peninsula. Soil development is poor due to the limited supply of organic matter. A reef platform extends 30-120 m from the shoreline around the whole island, being widest along the north coast. Further details are provided by Garnett (1983), UNEP/IUCN (1988) and IUCN (1991).

Kiritimati lies within the equatorial dry zone. The mean annual rainfall is 873 mm, varying widely between a minimum of 177 mm and a maximum of 2,621 mm. Rainfall is usually heaviest in March and April, and lightest in October and November. The temperature is constant, ranging diurnally between 24^oC and 30^oC, with little seasonal variation. The prevailing winds are easterly trades.

ECOLOGICAL FEATURES The native vegetation comprises forest, scrub, dwarf scrub, grassland and herb communities. Indigenous forest is restricted to three small groves of Pisonia grandis attaining a height of 10 m, at Southeast Point, Motu Tabu and near Northwest Point. The dominant scrub over most of the island is Scaevola taccada, in either pure stands or with Messerschmidia argentea and Suriana maritima. Lower lagoon flats are dominated by Suriana, growing to a maximum height of 2 m. Messerschmidia is found most commonly on the beach ridge, coastal plain and lagoon shores. Sida fallax, reaching 2 m in height, is abundant on the coastal plain to the south and on sandy soils elsewhere. Heliotropium anomalum forms a dwarf scrub on beach ridges and boulder ramparts, mixed with Portulaca lutea and P. oleracea. Extensive Sida dwarf scrub, mixed with Heliotropium, Boerhavia repens, Portulaca, Cassytha filiformis and Lepturus repens, is found in the Southeast Peninsula and southern coastal plains. Elsewhere, Lepturus-dominated grasslands cover large areas of coastal plain. The principal herbaceous community is dense Sesuvium portulacastrum mat which frequently covers the low-lying, waterlogged lagoon shore. Approximately 5,200 ha in the west have been planted with coconut palms (Cocos nucifera), and about 50 other introduced species occur, mainly around villages, abandoned military installations and other disturbed sites. Most alien species are believed to have arrived during the present century. Further details are provided by Garnett (1983) and IUCN (1991).

LAND TENURE Largely state owned.

CONSERVATION MEASURES TAKEN Kiritimati was gazetted as a bird sanctuary in December 1960, under the Gilbert and Ellice Island Colony Wild Birds Protection Ordinance of 1938. The three principal lagoon islets (Cook Island, Motu Tabu and Motu Upua) were declared reserves with restricted access. Under the 1975 Wildlife Conservation Ordinance, the entire island was re-gazetted as a Wildlife Sanctuary in May 1975, with five areas being designated as Closed Areas Cook Island (19 ha), a long, narrow islet at the entrance to the main lagoon; Motu Tabu (3.5 ha), a small islet with planted Pisona woodland in the main lagoon; Motu Upua (19 ha), a larger islet with Messerschmidia, Heliotropium, Suriana and Scaevola scrub and scattered Cocos nucifera; Ngaontetaake (2.7 ha), an islet in the east of the central lagoon; and Northwest Point, a traditional nesting area for Sooty Terns north of the main settlement. All are important nesting areas for sea birds, Motu Upua holding the largest extant colonies of Phoenix Petrel and Christmas Island Shearwater. Entry into the Closed Areas is prohibited except under written permit.

A Wildlife Conservation Unit was established on Kiritimati in 1977 to survey and monitor seabirds populations, enforce strict wildlife conservation legislation, control feral cats and pigs, and provide a conservation education programme. The Unit is represented on the Kiritimati Development Committee and the Local Land Planning Board. Garnett (1983) proposed a five-year management plan (1983-87) involving law enforcement, education and public awareness, surveys and research, advice to government, control of introduced species and appropriate development of tourism. Many of the activities proposed in this management plan have subsequently been carried out by the Wildlife Conservation Unit. A grant has been made available by New Zealand to fund programmes for the eradication of feral cats and pigs.

CONSERVATION MEASURES PROPOSED Garnett (1983) has recommended that the island as a whole loses its wildlife sanctuary status and that a number of specific areas be gazetted as wildlife sanctuaries, namely all the islets, the central lagoons, Northwest Point, Paris Peninsula and Southeast Peninsula. Within these proposed sanctuaries, it is recommended that the following areas be declared closed areas Cook Island, Motu Tabu, Motu Ubua, Ngaontetaake, Frigatebird Island and all Sooty Tern colonies.

LAND USE Kiritimati was bonded under the 1856 American Guano Act in June 1858, after which it was sporadically exploited for phosphate. The island has been occupied more or less continuously since 1882. By 1886, some 18,000-20,000 coconut palms had been planted, and 200 tons of pearl-shell exploited. A number of commercial concerns were licensed to exploit the island in the late 19th century, and some 70,000 coconut palms were planted at the turn of the century, although only 25% survived due to severe drought. The island was uninhabited from 1905 to 1912, but then followed large-scale development of coconut plantations by Central Pacific Coconut Plantation Ltd. The island was occupied by Allied forces during World War II, and an airstrip was constructed. From 1956 to 1958, atmospheric nuclear bomb tests were conducted by the U.K. some 50 km south of the island, and up to 4,000 servicemen were present. Further bomb tests were carried out by the U.S.A. in 1962. Military interests ceased in 1969, and many of the installations were dismantled. The surviving infrastructure of roads, wharfs and airport facilities have established Kiritimati as the administrative centre for the Line Islands. The principal economic activity is copra production, the Government copra plantation covering some 5,170 ha. The population in 1989 was estimated at 2,000, the great majority of whom live in London, Banana and Poland villages in the west. Recent developments include small-scale vegetable production and the export of live crayfish and chilled reef and ocean fish. A 1971 University of Hawaii expedition investigated the possibilities for production of brine shrimp (Artemia salina), and brine shrimp were introduced into the lagoon, but commercial implementation of the project was abandoned in 1978. A pilot project to determine the potential for salt production has been undertaken. In recent years, there has been some tourism to the island. Further details are given in Garnett (1983) and IUCN (1991).

DISTURBANCES AND THREATS Coconut plantations have replaced the natural vegetation over about a third of the land area. The indigenous Tree Heliotrope (Messerschmidia argentea) and other shrubs have been needlessly destroyed on several occasions in the name of agricultural projects that have turned out to be ill-conceived (Perry, 1980). Substantial changes have occurred in the ecology of the island as a result of the introduction of alien plants. The introduced Sourbush (Pluchea odorata) became widely dispersed during World War II, and forms thickets eliminating open habitats in some parts of the island. The low-growing vine Tribulus cistoides now dominates extensive open areas, but is to some extent beneficial in that it provides increased cover for some nesting seabirds (Perry, 1980). By 1978, there were over 50 species of exotic plants on the island (Perry, 1980). It is not known if the island was adversely affected by atmospheric nuclear bomb test programmes during 1956-58 and 1962. The El Nino-Southern Oscillation of 1982-83 had a devastating effect on seabird populations, leading to 90% mortality and no reproductive success in a number of species. Both numbers of birds and reproductive activity increased in 1983, but recovery was set back by the El Nino-Southern Oscillation of 1986-87.

Feral cats have been present on the island since the 19th century and pose the most serious threat to bird life. The feral cats feed almost entirely on seabirds, and their distribution is closely correlated with that of nesting seabirds. The total number of cats on the island, although showing considerable fluctuations, may at times exceed 2,000. As a result of predation by cats, 11 of the 18 breeding seabirds now nest only on lagoon islets that are free of cats. An exceptionally dry period during the latter part of 1978 resulted in the lowering of water levels in a number of shallow lagoons, enabling cats to move across to former islets where they extirpated several previously secure colonies of Grey-backed Terns (Perry, 1980). A cat eradication programme employing night-shooting has met with only limited success. However, the recruitment of stray domestic cats into the feral population has been countered by programmes of trapping in the villages since 1981, and by a local bye-law which makes it illegal to possess a female cat until it has been neutered.

Feral pigs formerly posed a serious threat to ground-nesting terns in particular, but intensive hunting has drastically reduced the numbers of pigs on the island in recent years. The Black Rat (Rattus rattus) has been recorded in the past, but apparently no longer persists. Tilapia (Oreochromis sp.) and brine shrimp (Artemia salina) have been introduced into the lagoons.

Direct exploitation of seabirds for food posed a serious threat to populations of Sooty Terns, Red-tailed Tropicbirds and boobies until 1977, when the wildlife conservation laws were enforced for the first time. The large-scale collection of Sooty Tern eggs for food occasionally resulted in complete nesting failure in some colonies. Tropicbirds were frequently killed for the sake of their tail streamers and other plumage feathers which were used in making fish lures and for decorating artifacts (Perry, 1980). Poaching remains a problem. An increase in fishing activity, better roads, cheaper and improved cross-country motor-cycles and the wider availability of outboard motors have all contributed to greater accessibility to previously remote parts of the island, with consequent increased disturbance and poaching at the seabird colonies. Red-tailed Tropicbirds, Red-footed Boobies and Masked Boobies, in particular, have suffered from the increased levels of poaching. There seems to be little prospect of these populations recovering to their pre-1982/83 levels, as long as feral cats and poaching are prevalent.

HYDROLOGICAL AND BIOPHYSICAL VALUES No information.

SOCIAL AND CULTURAL VALUES Archaeological research indicates that Kiritimati was visited by early Polynesians but not settled for prolonged periods. Remains include two sites which may have been villages, and a number of stone structures.

NOTEWORTHY FAUNA Thirty-seven species of birds have been recorded on the island, and 20 of these are known to breed. Kiritimati has the greatest variety and some of the largest populations of tropical seabirds anywhere in the world. Eighteen species of seabirds breed on the island. Population estimates prior to the 1982/83 El Nino included 12,000 pairs of Phoenix Petrels (Pterodroma alba), 500,000 pairs of Wedge-tailed Shearwaters (Puffinus pacificus), 6,000 pairs of Christmas Island Shearwaters (P. nativitatis), 500 pairs of White-throated Storm Petrel (Nesofregetta (fuliginosa) albigularis), 4,000 pairs of Red-tailed Tropicbird (Phaethon rubricauda), 1,500 pairs of Masked Booby (Sula dactylatra), 6,000 pairs of Red-footed Booby (S. sula), 6,000 pairs of Great Frigatebird (Fregata minor), 4,500 pairs of Lesser Frigatebird (F. ariel), 3 million to 4 million pairs of Sooty Terns (Sterna fuscata), 3,000 pairs of Grey-backed Tern (S. lunata), 2,000 pairs of Blue-grey Noddy (Procelsterna cerulea), 10,000 pairs of Black Noddy (Anous minutus) and 4,000 pairs of White Tern (Gygis alba) (Schreiber & Schreiber, 1984). The population of Sooty Terns, estimated at 15 million birds in the 1960s, remains the largest known population in the world despite the decline in recent years. The terns nest on five principal islets, two of which are in Closed Areas. The population of Phoenix Petrels is also the largest in the world, as is probably that of Wedge-tailed Shearwaters. Other internationally significant populations include those of the White-throated Storm Petrel, Red-tailed Tropicbird, Masked Booby, Great Frigatebird, Lesser Frigatebird, Grey-backed Tern and Blue-grey Noddy. Populations of all species declined to a greater or lesser extent following the devastating El Nino-Southern Oscillation of 1982 and 1983, and in most cases have remained below 1981 levels since then (Schreiber & Schreiber, 1984, 1989). There is only one indigenous land-bird, the Christmas Island Warbler (Acrocephalus aequinoctialis), which is fairly common except in the vicinity of settlements, favouring semi-open areas of native Lepturus grass with scattered Messerschmidia and Scaevola shrubs. The total population has been estimated at about 1,000 individuals (Garnett, 1983). The Scarlet-breasted or Kuhl's Lorikeet (Vini kuhlii) has been introduced to the island but remains scarce and local. Common migrants include the Pacific Golden Plover (Pluvialis fulva), Wandering Tattler (Heteroscelus incanus), Bristle-thighed Curlew (Numenius tahitiensis) and Ruddy Turnstone (Arenaria interpres). The type specimen of the Tuamotu Sandpiper (Prosobonia cancellatus) was collected on the island in January 1778, but the species has not been found there since.

The only mammal on the island, other than feral animals, is the Polynesian Rat (Rattus exulans), which is widespread and abundant. This was presumably introduced by early Polynesians. Green Turtles (Chelonia mydas) regularly come ashore in small numbers to nest. Mourning Geckoes (Lepidodactylus lugubris) and Snake-eyed Skinks (Ablepharus boutonii) are common, and the Stump-toed Gecko (Gehyra mutilata) has been recorded. Noteworthy invertebrates include Coconut Crabs (Birgus latro), ghost crabs (Ocypode spp.), land crabs (Cardisoma carnifex and Geograpsus grayii) and land hermit crabs (Coenobita perlata). Further details of the fauna are provided by Garnett (1983).

NOTEWORTHY FLORA The island has one endemic plant species, Cuscuta campestris.

SCIENTIFIC RESEARCH AND FACILITIES Kiritimati has been the subject of numerous studies and surveys. A considerable amount of research has been undertaken on the breeding seabirds (e.g. Schreiber & Ashmole, 1970; Garnett, 1982, 1983, 1984; Schreiber & Schreiber, 1984, 1989), while Milder and Schreiber (1982, 1989) have described the nesting behaviour and vocalizations of the Christmas Island Warbler. The University of Hawaii has several projects in the Line Islands and uses Kiritimati as a base. A meteorological observatory and projects on sea level rise and water temperature are based on the island. A bibliography of studies on the flora, fauna and past and present human use is given by Garnett (1983).

CONSERVATION EDUCATION The Wildlife Conservation Unit has developed an education and public awareness programme on the island.

RECREATION AND TOURISM An hotel and improved air connections with Honolulu have enabled the development of small-scale tourism for sport fishing and naturalists. Specialist wildlife tours consist of six-day guided visits to reserves, reefs and the Southeast Peninsula (Garnett, 1983).

MANAGEMENT AUTHORITY AND JURISDICTION Wildlife Conservation Unit, Ministry of the Line and Phoenix Groups.

REFERENCES Anon. (1985); Chock & Hamilton (1962); Dahl (1980, 1986); Garnett (1982, 1983, 1984); IUCN (1991); Milder & Schreiber (1982, 1989); Perry (1980); Schreiber & Ashmole (1970); Schreiber & Schreiber (1984, 1989); TCSP (1990); UNEP/IUCN (1988); Wildlife Conservation Unit (1985).

REASONS FOR INCLUSION 1a, 1d, 2a, 2b, 2c. The island is recognized as having considerable scientific and conservation importance for wildlife in the Central Pacific. It is particularly valued for the diversity and abundance of its seabird populations, with internationally significant breeding populations of 10-12 species. The large and complex system of partially and completely landlocked lagoons with hundreds of islets is unique in the Central Pacific.

SOURCE See references.