BirdLife species factsheet for Bonin White-eye Bonin White-eye Apalopteron familiare is restricted to the Ogasawara Islands, Japan, where it has been recorded from all three island groups, the Muko-jima, Chichi-jima and Haha-jima Islands. It is currently listed as Vulnerable under criterion C2a(ii) because it was thought to have a small, declining population as a result of the historical clearance of primary forest and continued threats to secondary forest from tourism and infrastructure developments, as well as from introduced pest species. The global population was previously estimated to number c.2,500-9,999 mature individuals (based on an estimate of 3,000-4,000 individuals on Haha-jima island (Kato et al. 1995), plus information from the other islands [BirdLife International 2001]). However, recent information suggests that this existing figure was an underestimate (S. Tadashi in litt. 2012, K. Kawakami in litt. 2012). Recent estimates, based on quantitative methods, suggest that the total population numbers 10,000-15,000 mature individuals (K. Kawakami in litt. 2012). Also, following considerable historical losses, the range and population are now thought to be stable (K. Kawakami in litt. 2012). The majority of the population is found on the main island, with only a few hundred individuals present on the two satellite islands, and analysis of DNA reveals that dispersal between the islands is very rare. Thus, they should be regarded as three distinct populations (Kawakami et al. 2008), and not one subpopulation as previously thought. Although limited to three islands, its distribution has not declined since World War II (K. Kawakami in litt. 2012). If this information is confirmed, and the population of this species is >10,000 mature individuals, is not in continuing decline and the vast majority, but not all individuals are not in one subpopulation, it would no longer qualify as Vulnerable and would warrant downlisting to Least Concern, or Near Threatened if it was still considered close enough to the the thresholds for Vulnerable under criterion C2a(ii) of the IUCN Red List. Information is requested on the population size, trends and distribution of this species. Additional comments on the proposed downlisting are welcome. References: BirdLife International. (2001) Threatened birds of Asia: the BirdLife International Red Data Book. BirdLife International: Cambridge, U.K. Kato, M., Numata, M., Watanabe, K. and Hata, M. (1995) Natural monuments of Japan. Kodansha: Tokyo. Kawakami, K., Harada, S., Suzuki, T. and Higuchi, H. (2008) Genetic and Morphological Differences Among Populationsof the Bonin Islands White-eye in Japan. Zoological Science 25, 882–887.
Kawakami and Higuchi (2013) estimated 14,700 individuals on Hahajima, 480 on Mukohjima and 420 on Imotojima, based on estimates of population densities in different habitats.
The population was considered to have been stable for several decades by Kawakami and Higuchi (2003).
Kawakami and Higuchi (2013) conducted a population viability analysis and found that the probability of extinction for the main (Hahajima) population remained 0% even when the carrying capacity decreased to 10% of its present value. They noted also that c.60% of the current forest area on Hahajima was cultivated before WWII and that the species may therefore be tolerant of habitat conversion.
The other two small populations were found to be more sensitive to any decrease in breeding success rate or carrying capacity.
Black rats are present on Hahajima, but do not currently seem to be affecting the population of white-eyes. Brown rats are apparently established on satellite islands of Hahajima.
Kawakami, K. and Higuchi, H. 2013. Estimation of the population size and viability of the Bonin White-eye Apalopteron familiare in the Bonin Islands, Japan. Ornithological Science 12: 51-56.
Kawakami, K. and Higuchi, H. 2003. Interspecific interactions between the native and introduced white-eyes in the Bonin Islands. Ibis 145: 583-592.