Christmas Island Hawk-owl (Ninox natalis)
Justification This species is restricted to one island location and is predicted to undergo a long-term decline greater than 80% in the next 30 years (three generations), due to the introduction of a highly destructive species of ant. It is therefore classified as Critical.
Identification 26-29 cm. Small, rufous-brown hawk-owl. Sexes similar, female slightly larger. Rufous-brown upperparts. Rows of small, white spots on secondary coverts, scapulars and tertials. Darker brown barring on remiges and tail. Narrowly barred white underparts. Underwing rufous-brown on coverts, barred light and dark grey on remiges. Yellow legs and feet. White lores, short supercilia and chin. Bright yellow iris in small, dark disc. Juvenile downier with whitish underside and head. Voice Double-noted hoot boo-book, second note usually lower in pitch than first. Juvenile begging call, high-pitched trill.
Taxonomy Previously considered a subspecies of Moluccan Hawk-owl N. squamipila, but its specific status has been recently confirmed.
Population estimate 1200
Population trend decreasing (continuing
Range estimate 137 km2
Country endemic? Yes
Range & Population Ninox natalis is restricted to Christmas Island (to Australia) in the Indian Ocean. The species is present throughout the island, with highest densities occurring in primary forest and the lowest in regrowth after mining. The population is declining and numbers 1,200 individuals.
Ecology It occupies permanent territories in all habitats on the island, although it is absent from mined sites. Its diet consists primarily of insects supplemented with small vertebrates, including the introduced black rat Rattus rattus.
Threats Forest clearance for phosphate extraction has destroyed 25% of available habitat, but has now been halted. The greatest current threat is from the introduced yellow crazy ant Anoplolepis gracilipes which is spreading rapidly across the island. These ants may prey directly on nestlings and, by killing the dominant life-form, the red crab Gecaroidea natalis, and by farming scale insects which damage the trees, are likely to alter the whole ecology of the island.
Action CITES Appendix II. A national park was created in 1980, and has since been extended. A lease agreement has been established with the mining company which prevents clearance of primary rainforest and requires permits to clear regrowth. A draft recovery plan has been prepared. Contingency plans are being developed to establish a captive population on mainland Australia. A control programme for A. gracilipes has been initiated.
