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Bonin White-eye Apalopteron familiare



Justification

Justification of Red List Category
This species has been downlisted from Vulnerable following evidence that its population is larger than previously estimated and is probably stable and not declining, as previously inferred. The species is listed as Near Threatened because it remains susceptible to the impacts of extreme weather events, which could result in it qualifying as threatened within one or two generations.

Population justification
This species's populations have been estimated at c.14,700 mature individuals on Hahajima, c.480 mature individuals on Mukohjima and c.420 mature individuals on Imotojima, based on data collected in the late 1990s (Kawakami and Higuchi 2013). These estimates are assumed to equate to a total population of c.15,600 mature individuals, probably equivalent to c.23,400 individuals in total.

Trend justification
Following considerable historical losses, the range and population are now thought to be stable (K. Kawakami in litt. 2012), and possibly have been for several decades (Kawakami and Higuchi 2003).

Distribution and population

Apalopteron familiare is endemic to the Ogasawara Islands, Japan, where it has been recorded from all three island groups, the Mukojima, Chichijima and Hahajima Islands. The nominate subspecies is now probably extinct, having been confined to Mukojima and not observed since the 1930s (del Hoyo et al. 2008). The species has also been extirpated from Chichijima (Suzuki and Morioka 2005). On Hahajima, it occurs on the main island and two small satellite islands—Imotojima and Mukohjima (Kawakami et al. 2008, Kawakami and Higuchi 2013), with the majority of the population found on the main island. Analysis of DNA reveals that dispersal between the islands is very rare and that they should be regarded as three distinct populations (Kawakami et al. 2008). This species's populations have been estimated at c.14,700 mature individuals on Hahajima, c.480 mature individuals on Mukohjima and c.420 mature individuals on Imotojima, based on data collected in the late 1990s (Kawakami and Higuchi 2013). Following considerable historical losses, the range and population are now thought to be stable. Kawakami and Higuchi (2013) conducted a population viability analysis and found that the probability of extinction for the main (Hahajima) population remained at 0% even when the carrying capacity decreased to 10% of its present value. The other two small populations were found to be more sensitive to any decrease in breeding success rate or carrying capacity (Kawakami and Higuchi 2013).

Ecology

It inhabits low secondary forest, forest edge, bushes, plantations and gardens. On Hahajima, it favours forest with well-developed undergrowth, feeding mainly 2-6 m above the ground, mostly on invertebrates. Nests are situated in tree forks and occasionally in tree cavities (Kawakami and Higuchi 2002b).

Threats

Virtually all the original subtropical forest has already been cleared from the Ogasawara Islands, leading to extinction on several islands, presumably as a result of the wholesale destruction of its habitat. Economic development on Hahajima Island, including developments for tourism, and a consequent reduction in forest cover, may have important implications for the species. However, Kawakami and Higuchi (2013) noted that c.60% of the current forest area on Hahajima was cultivated before World War II and that the species may therefore be tolerant of habitat conversion. Further invasions by exotic species remain a potential problem. Predation by domestic and feral cats may pose a minor threat (Kawakami and Higuchi 2002a). Nest predation by introduced black rats may be a threat on Hahajima (Kawakami in litt. 2012), but rats do not currently seem to be affecting the population. Brown rats are apparently established on the satellite islands of Hahajima. Competition with introduced Japanese White-eye Zosterops japonicus was found to have little or no negative effect on this species (Kawakami and Higuchi 2003).

Conservation actions

Conservation Actions Underway
It is legally protected in Japan. The Ogasawara Islands are a National Wildlife Protection Area, established primarily for this species. An active conservation programme is underway there, including the propagation and reintroduction of threatened native plants. Feral cat eradication is on-going on Hahajima. Invasive trees are being removed from Hahajima and its satellites. Rat eradication is planned for Imotojima and Mukohjima.

Conservation Actions Proposed
Continue to survey islands in its range to determine population trends and identify islands that still support populations. Establish a monitoring programme on Hahajima Island. Promote habitat protection and restoration of forest with well-developed undergrowth on Hahajima Island and other smaller islands where populations persist. Study the reasons for its extinction on previously occupied islands, and evaluate current threats to extant populations. Study the feasibility of reintroduction to other islands in Ogasawara, including the establishment of a captive breeding programme to support such actions.

Identification

13.5 cm. Small, yellow and olive-green honeyeater with a distinctive facial pattern. Mainly olive-green upperparts with yellowish tinge, pale yellow below with grey on flanks. Black patch extends from above to below eye and joins black line across forehead. White eye-ring. Black legs. Voice Various whistling calls.

Acknowledgements

Text account compilers
Benstead, P., Gilroy, J., Khwaja, N., Taylor, J., Allinson, T, North, A.

Contributors
Suzuki, T., Kawakami, K.


Recommended citation
BirdLife International (2019) Species factsheet: Apalopteron familiare. Downloaded from http://www.birdlife.org on 18/10/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/10/2019.