Data Zone
Justification of Red List category
Although it has a very restricted range, the population size of this species exceeds 10,000 mature individuals and the population trend appears to be stable. There are also no plausible threats that could cause this species to rapidly become Critically Endangered or Extinct. For these reasons it is assessed as Least Concern.
Population justification
Survey data suggest that the species continues to be highly abundant (Macgregor et al. 2021). The population on Christmas Island was most recently (in 2003) estimated at 80,000–170,000 mature individuals (Corbett et al. 2003, Beeton et al. 2010), although this may be an overestimate (Macgregor et al. 2021) with previous suggestions of just 20,000 mature individuals (Garnett & Cowley 2000, Garnett et al. 2010). The population is not thought to have changed substantially in size since. The population on Horsburgh Island lies outside the species' native range and was not introduced for conservation purposes, hence is not considered part of the global population size herein. Nonetheless, the number of mature individuals on Horsburgh has been estimated at 1,084 individuals (95% CI: 731–1,716; Woinarski et al. 2014). Population bands are therefore broad, set between 20,000 and 170,00 with a best estimate, following the most recent evaluation of the evidence (Macgregor et al. 2021) of 125,000 mature individuals.
Trend justification
There are no acting threats thought capable of causing declines and so the species is suspected to be stable. In 2005–2006, the species was detected in 99% of surveys specifically for birds (128 sites repeated four times) and, in more general island-wide surveys, at 92% of 933 sites in 2011 and 91% and 89% of 1,106 sites surveyed in 2013 and 2015, respectively (Director of National Parks unpublished, in Macgregor et al. 2021), all of which suggests the species continues to be highly abundant.
The species occurs naturally only on Christmas Island, Australia, where it is widespread (James and McAllan 2014). Between 1888 and 1900, the species was also introduced to Horsburgh Island in the Cocos (Keeling) islands for reasons that are not recorded (Woinarski et al. 2014).
It is found in all forested habitats on Christmas Island up to 360 m (D. James in litt. 2007). It also occurs in suburban gardens and weeds fields in abandoned mine sites (D. James in litt. 2007). There is no other species competing for food in its niche between the canopy and the lower-bole zone.
Historically, phosphate mining and other development removed a substantial area of white-eye habitat, but they are still present everywhere with shrubs or trees (James & McAllan 2014) and no clearing of Christmas Island's old-growth forest (primary vegetation) has been permitted since 1988. The introduced yellow crazy ant Anoplolepis gracilipes, which formed super-colonies during the 1990s and spread rapidly to cover about 25% of the island or about 3,400 ha, but was controlled over about 2,900 ha in September 2002, was once thought to be a potential threat; however, the species has proven even more abundant in areas where ants persist because it can feed on the same psyllid honeydew as the ants (Davis et al. 2008, Macgregor et al. 2021). Black rats Rattus rattus are not known to affect the population size on Christmas Island (James & McAllan 2014), but almost certainly prevented establishment of translocated birds on all islands of the southern atoll of the Cocos (Keeling) group other than the rat-free Horsburgh Island (Woinarski et al. 2014, Macgregor et al. 2021). There has been no effective management of black rats on Christmas Island. Cats Felis catus also kill many individuals on Christmas Island (present in 13% of gut samples, Tidemann et al. 1994; present in 16% of scats, Corbett et al. 2003), but are being managed with the goal of eradicating them from the island (Johnston et al. 2020).
Conservation Actions Underway
The Christmas Island National Park was established in 1980, and has since been extended to cover more than 60% of the island (D. James in litt. 2007). The introduced population on the Cocos (Keeling) Island might serve as an insurance population if unforeseen catastrophe was to effect the population on Christmas Island (Woinarski et al. 2014).
11-13 cm. Small, warbler-like bird lacking bright yellow colouring. Sexes alike. Dull green above, greyish-white below. White eye-ring. Dull brownish primaries, secondaries and tail, edged green. Black lores, continuing to halfway under eye-ring. Bright chestnut iris in adults, grey in juveniles. Pale yellow undertail-coverts. Black bill, pale grey base to lower mandible. Similar spp. Vagrant Arctic Warblers Phylloscopus borealis are possible. Voice Variable, includes chirping, twittering. Hints Smallest bird in range. Flocks forage in all levels of vegetation.
Text account compilers
Garnett, S., Vine, J., Berryman, A.
Contributors
Blyth, J., Garnett, S., Green, P., Hennicke, J., James, D., Low, T. & O'Dowd, D.
Recommended citation
BirdLife International (2024) Species factsheet: Christmas Island White-eye Zosterops natalis. Downloaded from
https://datazone.birdlife.org/species/factsheet/christmas-island-white-eye-zosterops-natalis on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/12/2024.