Bonin White-eye

The Bonin white-eye is, at its name suggests, endemic to the Bonin Islands, south of Japan. The species was once found on all the major groups of islands in the chain, including the Mukojima Group, the Chichijima Group and the Hahajima. Presently its habitat is restricted to Hahajima Island and two nearby islands, having become extinct across the rest of its previous range. The species' presence on Chichijima Island has been the subject of debate and dispute. The species has been introduced to Chichijima from Hahajima, so it was assumed that all records related to that introduction, but its natural presence on the island, and subsequent extinction, was subsequently established from early accounts, and a bird from that island was the type specimen for the species. All records of the species in the Chichijima Group are from the main Chichijima Island. On Hahajima, the only island that its habitat preferences have been studied on, the species occupies almost every habitat type. It occupies undisturbed native evergreen and broadleaf forest, dominated by Schima and Ardisia, as well as secondary and disturbed forest and other human modified habitats. The species occupies a wide range of modified habitats during the non-breeding season, but is more localised when breeding, when it is predominantly found in undisturbed native forest with large trees and bamboo, tree ferns and large shrubs. It is much rarer on the windy ridges of the mountains, where the vegetation is short and shrubby. Local fishermen on Hahajima have reported that the species disperses to the smaller islands of the group during the autumn and winter, but these localised movements have not been confirmed.

The Bonin white-eye is evaluated as being "near threatened" by the IUCN Red List. The nominate race, of Mukojima and Chichijima is thought to be extinct. Its current status on Chichijima is uncertain, and it was reintroduced there and may have persisted, although a 2003 study of the species found none there. The reasons for its extinction on these two islands are unknown. It is thought that habitat loss, specifically the clearance of primary forest, may be a cause. The species' status on Hahajima seems more secure. It was considered vulnerable, as population estimates put the number of birds on the island at around 4,000. More accurate censusing, which took into account both densities of birds and how they varied by habitat, re-estimated the population at over 15,000. The same study evaluated that the species was not in immediate threat of extinction. On the basis of the study it was downlisted to near threatened in 2013. The species is preyed upon by introduced cats; it is particularly vulnerable due to its tendency to feed on the ground, and its nests are raided by introduced rats. It is also somewhat threatened by the loss of native forest, for agriculture and tourism. Overall however the species is resilient to some degree to habitat modification, introduced predators and competitors, and its population is thought to be stable. It remains listed as near threatened, in spite of the stable population, due to a susceptibility to extreme weather events which could decimate the species. The Bonin white-eye is protected under Japanese law as a National Endangered Species. The Bonin Islands have been designated a National Wildlife Protection Area, in part to help protect this species. Efforts are underway to remove cats and rats from the islands, as well as remove invasive trees and restore native trees. Conservationists have suggested regular monitoring of the species be started and the feasibility of translocating birds to islands they have been lost from to create more populations and lessen the risk of a single incident wiping the species out.