Kiritimati or Christmas Island is a Pacific Ocean atoll in the northern Line Islands and part of the Republic of Kiribati. Nuclear tests were conducted on the island by the United Kingdom in the late 1950s. During these tests islanders were not evacuated. Subsequently British servicemen as well as local islanders have claimed to have suffered from exposure to the radiation from these blasts.
The island has the greatest land area of any coral atoll in the world: about ; it is about in perimeter, while the lagoon shoreline extends for over . Kiritimati comprises over 70% of the total land area of Kiribati, a nation encompassing 33 Pacific atolls and islands. It lies north of the Equator, from Sydney, and from San Francisco.
Its roughly lagoon opens to the sea in the northwest; Burgle Channel (the entrance to the lagoon) is divided into the northern Cook Island Passage and the southern South Passage. The southeastern part of the lagoon is partially dried out today; essentially, progressing SE from Burgle Channel, the main lagoon gradually turns into a network of subsidiary lagoons, tidal flats, partially hypersaline brine ponds and salt pans, which as a whole has about the same area again as the main lagoon. Thus, the land and lagoon areas can only be given approximately, as no firm boundary exists between the main island body and the salt flats.
Kiritimati is the first inhabited place on Earth to experience the New Year each year (see also Caroline Atoll, Kiribati). Despite being east of the 180 meridian, a 1995 realignment of the International Dateline by the Republic of Kiribati 'moved' Kiritimati to west of the dateline.
"Kiritimati" may look like a typical "Polynesian" name, but this is by no means correct. Actually, it is a rather straightforward transliteration of "Christmas" into Gilbertese – where the 'ti' combination is pronounced 's' – and thus .Similarly Kiribati is a transliteration of Gilberts with the K replacing the G and the R replacing the L. Moreover, Gilbertese is a Micronesian language.
At Western discovery, Kiritimati was uninhabited. Like on other Line Islands, there may have been a small and/or temporary native population, most probably Polynesian traders and settlers. These would have found the island a useful replenishing station on the long voyages from the Society Islands to Hawaiʻi, perhaps as early as 400 AD. This trade route was apparently used with some regularity by about 1000 AD. From 1200 AD onwards, Polynesian long-distance voyaging became less frequent, and if there ever was human settlement on Kiritimati, it would have been abandoned in the early-mid second millennium AD. Two possible village sites and some stone structures of these early visitors have been located. Today, most inhabitants are Micronesians, and Gilbertese is the only language of any significance. English is generally understood, but little used outside the tourism sector.
Kiritimati was discovered by Captain James Cook on Christmas Eve (December 24), 1777. It was claimed by the United States under the Guano Islands Act of 1856, though little actual mining of guano took place. This claim was formally ceded by the Treaty of Tarawa between US and Kiribati, signed in 1979 and ratified in 1983. Permanent settlement started by 1882, mainly by workers in coconut plantations and fishermen, but due to an extreme drought which killed off tens of thousands of Coconut Palms – about 75% of Kiritimati's population of this plant – the island was once again abandoned between 1905 and 1912.
Many of the toponyms in the island go back to Father Emmanuel Rougier, a French priest who leased the island from 1917 to 1939 and planted some 800,000 coconut trees there. He lived in his Paris house (now only small ruins) located at Benson Point, across the Burgle Channel from Londres (today London) at Bridges Point where he established the port.
In World War II, Kiritimati was occupied by the Allies, and the first airstrip was constructed then, for servicing the US Army Air Force weather station communications center. The airstrip also provided rest and refueling facilities for planes traveling between Hawaii and the South Pacific. There was also a small civilian radio-meteorological research station.
The United Kingdom detonated some 5 megatons of nuclear payload near and 1.8 megatons directly above Kiritimati in 1957/58, while the USA between 25 April and 11 July, 1962 successfully tested nuclear devices of about 24 megatons payload altogether in the vicinity of the island. During the British Grapple X test of November 8, 1957, which took place directly above the southeastern tip of Kiritimati, yield was stronger than expected and there was some blast damage in the settlements. Islanders were usually not evacuated during the nuclear testing, and data on the environmental and public health impact of these tests remains contested.
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London is the main village and port facility. Banana is near Cassidy International Airport but may be relocated closer to London to prevent contamination of its groundwater. The abandoned village of Paris is not listed in census reports anymore.
The ministry of the Line and Phoenix islands is located in London. There are also two new high schools on the road between Tabwakea and Banana: one Catholic and one Protestant. The University of Hawaii has a climatological research facility on Kiritimati.
Cassidy International Airport (IATA code CXI), the only airport in Kiribati to serve the Americas, is located just north of Banana and North East Point. It has a paved runway with a length of . The abandoned Aeon Field, constructed before the British nuclear tests, is located on the southeastern peninsula, NW of South East Point.
In the early 1950s, Wernher von Braun proposed using this island as a launch site for manned spacecraft. There is a Japanese JAXA satellite tracking station; the abandoned Aeon Field had at one time been proposed for reuse by the Japanese for their now-canceled HOPE-X space shuttle project. Kiritimati is also located fairly close to the Sea Launch satellite launching spot at 0° N 154° W, about 370 km (200 nautical miles) to the east in international waters.
Most of the atoll's food supplies have to be imported. Potable water can be in short supply, especially around November in La Niña years. A large and modern jetty, handling some cargo, was built by the Japanese at London. Marine fish provide a healthy portion of the island's nutrition, although overfishing has caused a drastic decrease in the populations of large, predatory fish over the last several years.
Exports of the atoll are mainly copra (died coconut pulp); the state-owned coconut plantation covers about . In addition, goods like aquarium fish and seaweed are exported; a 1970s project to commercially breed Artemia salina brine shrimp in the salt ponds was abandoned in 1978. In recent years there are attempts to explore the viability of live crayfish and chilled fish exports and salt production.
Furthermore, there is a small amount of tourism, mainly associated with anglers interested in lagoon fishing (for bonefish in particular) or offshore fishing. Week-long ecotourism packages during which some of the normally closed areas can be visited are also available. There is some tourism-related infrastructure, such as a small hotel, rental facilities, and takeaways.
Joe's Hill (originally La colline de Joe) near Artemia Corners on the southeastern peninsula is the highest point on the atoll, at about ASL. On the northwestern peninsula for example, the land raises only to some 7 m (20 ft), which is still considerable for an atoll.
Despite its proximity to the ITCZ, Kiritimati is located in an equatorial dry zone and rainfall is rather low except during El Niño years; on average per year, in some years it can be as little as and much of the flats and ponds can dry up such as in late 1978. On the other hand, in some exceptionally wet years abundant downpours in March-April may result in a total annual precipitation of over . Kiritimati is thus affected by regular, severe droughts. These is exacerbated by its geological structure; climatically "dry" Pacific islands are more typically located in the "desert belt" at about 30°N or S latitude. Kiritimati is a raised atoll, and although it does occasionally receive plenty of precipitation, little is retained given the porous carbonatic rock, the thin soil, and the absence of dense vegetation cover on much of the island, while evaporation is constantly high. Consequently, Kiritimati is one of the rather few places close to the Equator which have an effectively arid climate.
Scaevola taccada (Beach Naupaka) is the most common shrub on Kiritimati; Beach Naupaka scrub dominates the vegetation on much of the island, either as pure stands or interspersed with Velvet Soldierbush (Tournefortia argentea) and Bay Cedar (Suriana maritima). The latter species is dominant on the drier parts of the lagoon flats where it grows up to 2 meters (7 ft) tall. Velvet Soldierbush is most commonly found a short distance from the sea- or lagoon-shore. In some places near the seashore, a low vegetation dominated by Polynesian Heliotrope (Heliotropium anomalum), Yellow Purslane (Portulaca lutea) and Common Purslane (P. oleracea) is found. In the south and on the sandier parts, Sida fallax, also growing up to 2 meters tall, is abundant. On the southeastern peninsula, S. fallax grows more stunted, and Polynesian Heliotrope, Yellow and Common Purslane as well as the spiderling Boerhavia repens, the parasitic vine Cassytha filiformis, and Pacific Island Thintail (Lepturus repens) supplement it. The last species dominates in the coastal grasslands. The wetter parts of the lagoon shore are often covered by abundant growth of Shoreline Purslane (Sesuvium portulacastrum).
Perhaps the most destructive of the recently-introduced plants is the camphorweed Pluchea odorata (Sweetscent), which is considered an invasive weed as it overgrows and displaces herbs and grasses. The introduced creeper Tribulus cistoides, despite having also spread conspicuously, is considered to be more beneficial than harmful to the ecosystem, as it provides good nesting sites for some seabirds.
More than 35 bird species have been recorded from Kitirimati. As noted above, only the Bokikokiko (Acrocephalus aequinoctialis), perhaps a few Rimitara Lorikeets (Vini kuhlii) – if any remain at all – and the occasional Eastern Reef Egret (Egretta sacra) make up the entire landbird fauna. About 1,000 adult Bokikokikos are to be found at any date, but mainly in mixed grass/shrubland away from the settlements.
On the other hand, seabirds are plentiful on Kiritimati, and make op the bulk of the breeding bird population. There are 18 species of seabirds breeding on the island, and Kitirimati is one of the most important breeding grounds anywhere in the world for several of these:
Kiritimati's lagoon and the saltflats are a prime location for migratory birds to stop over or even stay all winter. The most commonly migrants are Ruddy Turnstone (Arenaria interpres), Pacific Golden Plover (Pluvialis fulva), Bristle-thighed Curlew (Numenius tahitiensis) and Wandering Tattler (Tringa incana); other seabirds, waders and even dabbling ducks can be encountered every now and then. See also "Extinction" below.
Up to 2,000 feral cats can in some years be found on the island; the population became established in the 19th century. Their depredations seriously harm the birdlife. Since the late 19th century, they have driven about 60% of the seabird species from the mainland completely, and during particular dry spells they will cross the mudflats and feast upon the birds on the motus. Grey-backed Tern chicks seem to be a favorite food of the local cat population. There are some measures being taken to ensure the cat population does not grow. That lowering the cat population by some amount would much benefit Kiritimati and its inhabitants is generally accepted, but the situation is too complex to simply go and eradicate them outright (which is theoretically possible; see Marion Island) - see below for details. A limited population of feral pigs exists. They were once plentiful and wreaked havoc especially on the Onychoprion and noddies. Pig hunting by locals has been encouraged, and was highly successful at limiting the pig population to a sustainable level, while providing a source of cheap protein for the islanders.
There are some "supertramp" lizards which have reached the island by their own means. Commonly seen are the Mourning Gecko (Lepidodactylus lugubris) and the skink Cryptoblepharus boutonii; the Four-clawed Gecko (Gehyra mutilata) is less often encountered.
Green Turtles (Chelonia mydas) regularly nest in small numbers on Kiritimati. The lagoon is famous among sea anglers worldwide for its Bonefish (Albula vulpes), and has been stocked with Oreochromis tilapia to decrease overfishing of marine species. Though the tilapias thrive in brackish water of the flats, they will not last long should they escape in the surrounding ocean.
There are some crustaceans of note to be found on Kiritimati and in the waters immediately adjacent. The amphibious Coconut Crab (Birgus latro) is not as common as for example on Teraina. Ghost crabs (genus Ocypode), Cardisoma carnifex and Geograpsus grayi land crabs, the Strawberry Land Hermit Crab (Coenobita perlatus), and the introduced brine shrimp Artemis salina which populates the saline ponds are also notable.
In December 1960, the British colonial authority gazetted Kiritimati as a bird sanctuary under the 1938 Gilbert and Ellice Island Colony Wild Birds Protection Ordinance of 1938. Access to Cook Island, Motu Tabu and Motu Upua was restricted. Kititimati was declared a Wildlife Sanctuary in May 1975, in accordance with the Wildlife Conservation Ordinance of the then self-governing colony. Ngaontetaake and the Sooty Tern breeding grounds at North West Point also became restricted-access zones. Two years later, active conservation measures got underway.
To a limited extent, permits to enter the restricted areas for purposes like research or small-scale ecotourism are given. Kiribati's Wildlife Conservation Unit participates in the Kiritimati Development Committee and the Local Land Planning Board, and there exists an integrated program of wildlife conservation and education. New Zealand is a major sponsor of conservation efforts on Kiritimati.
Egg collecting for food on a massive scale was frequent in the past but is now outlawed. It is to be noted that the Sooty Terns for example could sustain occasional collection of effectively all of a season's eggs (over 10 million), if given sufficient time to recover and if cats are absent. Even egg collecting on a scale that significantly decreases costly food imports thus in theory could be possible, but not until the cat and rat populations have been brought under control. Poaching remains a concern; with the population rising and spreading out on Kiritimati, formerly remote bird colonies became more accessible and especially the Red-tailed Tropicbirds and the Sula are strongly affected by hunting and disturbance. Tropicbirds are mainly poached for their feathers which are used in local arts and handicraft; it would certainly be possible to obtain them from living birds as it was routinely done at the height of the Polynesian civilization.
It may seem that the erstwhile numbers of seabirds may only ever be approached again even remotely is the wholesale eradication of the feral cats. While this has been since shown to be feasible, it is not clear whether even a severe curtailing of the cat population would be desirable. Though it previously was assumed that the small Polynesian Rat is of little if any harm for seabirds, even house mice have been shown to predate seabird nestlings. Most nesting birds, in particularly Procellariiformes, are now accepted to be jeopardized by Rattus exulans. The Kiritimati cats are meanwhile very fond of young seabirds; it even seems that their behavior has shifted accordingly, with cats being less territorial generally and congregating in numbers at active bird colonies, and generally eschewing to hunt rats when seabird chicks are in plenty.
Though control of cats should be undertaken, it needs to be carefully controlled and accompanied by in-depth study. As cat populations are lowered, it must be feared that the rats respond with an increase before many birds will, trading one threat for another (see also Macquarie Island, where rabbit populations exploded after cat eradication). It might, in the long run, even make matters worse as the rats are less unwilling to cross the shallows to get to especially plentiful feeding sites than cats. Possession of an unneutered female cat on Kiritimati is illegal, and owners need to prevent their domestic cats from running wild (such animals are usually quickly killed in traps set for this purpose). Nighttime cat hunting has made little effect on the cat population. But as noted above, vigorous protecting of active nesting grounds from cats by traps, poison and supplemented by shooting while otherwise leaving them alone to hunt rats may well be the optimal solution.
There is no reliable data on the environmental and public health impact of the nuclear tests conducted on the island in the late 1950s. A 1975 study claimed that there was negligible radiation hazard; certainly, fallout was successfully minimized. More recently however, a Massey University study of New Zealand found chromosomal translocations to be increased about threefold on average in veterans who participated in the tests; most of the relevant data remains classified to date however.
The 1982/83 "mega-El Niño" devastated seabird populations on Kiritimati. In some species, mortality rose to 90% and breeding success dropped to zero during that time. In general, El Niño conditions will cause seabird populations to drop, taking several years to recover at the present density of predators. Global warming impact on Kiritimati is thus unpredictable. El Niño events seem to become shorter but more frequent in a warmer climate. Much of the island's infrastructure and habitation, with the notable exception of the airport area, is located to the leeward and thus somewhat protected from storms. A raising sea level does not appear to be particularly problematic; the increasing flooding of the subsidiary lagoons would provide easily-observed forewarning, and might even benefit seabird populations by making the motus less accessible to predators. In fact, geological data suggests that Kiritimati has withstood prehistoric sea level changes well. The biggest hazard caused by a changing climate would seem to be more prolonged and/or severe droughts, which could even enforce the island's abandonment as they did in 1905. However, it is not clear how weather patterns would change, and it may be that precipitation increases.
It may have been, but probably was not, limited to Kiritimati; while no remains have been found, little fieldwork has been conducted and judging from the Tuamotu Sandpiper's habits, almost all Line Islands would have offered suitable habitat. The Kiritimati population of P. cancellata disappeared in the earlier part of the 19th century or so, almost certainly due to predation by introduced mammals. While Prosobonia generally manage to hold their own against Polynesian Rats, they are highly vulnerable to the Black Rat and feral cats. Given the uncertainties surrounding the introduction date and maximum population of the former, the cats seem to be the main culprits in the Kiritimati Sandpiper's extinction.
Given that the island was apparently settled to some extent in prehistoric times, it may already have lost bird species then. The geological data indicates that Kiritimati is quite old, was never underwater in the Holocene at least, and thus it might have once harbored highly distinct wetland birds. The limited overall habitat diversity on Kiritimati nonetheless limits the range of such hypothetical taxa, as does biogeography due to its remote location. At least one, possibly several Gallirallus and/or Porzana rails make the most likely candidates, given their former presence in the region and that conditions on Kiritimati would seem well suited. Perhaps a Todiramphus kingfisher was also present; such a bird would probably have belonged to the Sacred Kingfisher (T. sanctus) group as that species today occurs as a vagrant in Micronesia, and related forms are resident in SE Polynesia. These birds would have fallen victim to the Polynesian Rats and, in the case of the rails which would have almost certainly been flightless, hunting by natives.