Christmas Island, an external territory of Australia, is a raised coral island in the Indian Ocean, c.200 km south of Java in Indonesia (EBAs 160 and 161) and 2,600 km west of Darwin in North-West Australia (EBA 187).

The native vegetation includes mixed closed rain forest above 180 m, occasionally extending down to coastal terraces where deciduous forest predominates (Davis et al. 1986).

The best known member of the island’s fauna is probably the endemic terrestrial red crab Gecarcinus lagostomus, whose estimated 135 million individuals make spectacular annual migrations, which have captured international attention through wildlife documentaries.

The island is also important for its bird species and, in particular, for its two endemic land birds. These both rely primarily on forest: Ducula whartoni is largely restricted to remaining patches, while Zosterops natalis occurs more widely in a variety of habitats.

Two seabirds, Abbott's Booby Papasula abbotti and Christmas Island Frigatebird Fregata andrewsi, are endemic while breeding, and also rely on the remaining forest for nesting sites.

In 1887 rock specimens collected from Christmas Island were shown to be rich in phosphate, a discovery which led to a century of phosphate mining on the island (stopped in 1987 and recommenced in 1990, but then restricted to previous cleared areas: T. Stokes in litt. 1993). The mining and associated settlement has resulted in severe disturbance of the natural environment, including the loss of c.25% of native forest and consequent declines in forest species.

Feral populations of introduced cats, rats and mice have also affected the wildlife, as does (or did) hunting by people (Stokes 1988). The exotic wolf snake Lycodon aulicus capucius, is a more recent, but established, introduction (in shipping cargo in 1987), and, as its diet is small animals it may threaten some bird species, especially passerines (T. Stokes in litt. 1993), although there is no evidence that this has happened (Rumpff 1992; but see the effects of the introduced brown tree snake Boiga irregularis on forest birds in Guam, EBA 189).

Of the two endemic landbird species, Ducula whartoni is considered threatened on account of its particularly small range; a widespread introduced shrub, the cherry Muntingia calabura, does now provide an alternative food source, but the total area occupied by the bird is still likely to be less than 100 km². Hunting is now illegal and has presumably been reduced, but it continues at an unknown level; D. whartoni does remain, however, widespread and common (Garnett 1993, R. Hill in litt. 1995).

Two subspecies, both rain forest inhabitants, are classified as threatened by Garnett (1993): the Christmas Island form of Brown Goshawk Accipiter fasciatus natalis (population estimated at 50-150 pairs) and Moluccan Hawk-owl Ninox squamipila natalis (c.100 pairs). The local race of Emerald Dove Chalcophaps indica natalis, also a rain forest bird but tolerant of disturbed habitats, is identified as being a taxon of special concern.

Both endemic seabirds (see 'Restricted-range species', above) are classified as Vulnerable on account of their tiny breeding ranges. The population of Papasula abbotti (3,000 pairs in 1991) continues to decline, despite the cessation of new forest clearance, because air turbulence downwind of clearings kills adults and young, and crowding by displaced breeders reduces productivity of pairs breeding elsewhere in the forest (Garnett 1993, Reville and Stokes 1994; see also Yorkston and Green 1997). The population of Fregata andrewsi has also declined (currently estimated at 1,600 pairs) and the potential for this slow-breeding species to recover from these losses is low.

There is one protected area, on the south-west of the island, the Christmas Island National Park, which has recently been extended to include c.62% of the island (Garnett 1993), and a new management plan has been developed. This will benefit all the endemic landbirds and the seabirds too, as virtually all nesting sites of Papasula abbotti are included within the park and c.20% of mined areas adjacent to nesting sites have been planted in a continuing restoration programme (R. Hill in litt. 1994). Two of the three colonies of Fregata andrewsi are within the park, though the third, which lies outside, continues to be degraded by phosphate dust from mining activities (R. Hill in litt. 1995).

Stattersfield, A. J., Crosby, M. J., Long, A. J. and Wege, D. C. (1998) Endemic Bird Areas of the World. Priorities for biodiversity conservation. BirdLife Conservation Series 7. Cambridge, UK: BirdLife International.

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Christmas Island. Downloaded from https://datazone.birdlife.org/eba/factsheet/180 on 22/12/2024.