Boninbrillenvogel

Bestimmung

The Bonin white-eye is 12 to 14 cm (4.7–5.5 in) long and weighs around 15 g (0.53 oz). The nominate race has a yellow head with a conspicuous triangular black eye-patch which is linked by the thin black line to a black forehead. The white eye-ring is broken by a thin black line through the eye. The lores are yellow, as are the throat and upper breast. The back and wings are olive-green tinged with grey, and the primaries are tinged with brown. The tail is olive-brown, and the underparts are pale yellow, with a grey wash on the flanks. The iris of the eye is brown, and the bill and legs are dark grey. The sexes are alike, and juveniles look very similar to the adults. The race hahasima is very similar to the nominate race, but the upperparts are tinged in yellowish-green tinge. It also has a slightly larger bill and tarsus.<p>Flight in this species is generally slow and direct, with fast sustained flight only being observed in chases between rivals. Aside from the chases, gliding and hopping were more common than flight, and individuals would usually climb trees by climbing branches and hopping; direct flights from the ground to the canopy are rare. The tarsus is long and the toes and claws are strong, especially compared to white-eyes in the genus Zosterops, reflecting its more terrestrial lifestyle. On the ground it hops rather than walks, in the manner of a thrush.

Taxonomie

The Bonin white-eye was described by Heinrich von Kittlitz in 1830 based on specimens collected on Chichijima in the Bonin Islands. Kittlitz placed the species in the bulbul (family Pycnonotidae) genus Ixos. He gave the species the specific name familiare from the Latin for familiar or friendly, as the species was the first bird that visitors would encounter, much like the house sparrow in Europe. In 1854 Charles Lucien Bonaparte moved it to its own genus, Apalopteron. The name is derived from the Ancient Greek hapalos for delicate and ptilon for feather. Bonaparte also placed it with the Old World babblers, then a subgrouping (Timaliini) of an enlarged Old World warbler family (Sylviidae). Richard Bowdler Sharpe moved it back to the bulbul family in 1882, and placed it in the genus Pycnonotus. It was moved back to the babblers again by Jean Théodore Delacour in 1946, before Herbert Girton Deignan placed it with the Australasian honeyeaters (family Meliphagidae) in 1958, on the basis of tongue structure, bill shape, nest structure and a number of other morphological features.<p>The species remained with the honeyeaters for many decades, although some authors questioned the placement, especially as it was the only honeyeater in the North Pacific and there were no members of that family in the Philippines, the island group between that family's natural range and the Bonin Islands. Finn Salomonsen, writing in 1967, thought that the golden white-eye (Cleptornis marchei) of the Marianas Islands might be a close relative, and the species was then known as the golden honeyeater. Hiroyuki Morioka and Takaharu Sakane also attributed the species to the honeyeaters, but cautioned that this was a provisional placement as the structure of the tongue was not very different from that of babblers. They also noted that it was very similar in diet and habitat preferences to the warbling white-eye, which had been introduced and was coexisting with the Bonin white-eye.<p>The discovery that the golden white-eye was indeed a white-eye and not a honeyeater, based on behavioural observations by H. Douglas Pratt and the genetic research of Charles Sibley and Jon E. Ahlquist, was the impetus for the resolution of the Bonin white-eye's family placement. Sibley came to suspect that this meant that the Bonin white-eye had been similarly misassigned to the honeyeaters. Hiroyoshi Higuchi independently had reached the same conclusion, and so Higuchi and Keisuke Ueda obtained specimens for Sibley, who enlisted Mark S. Springer to analyse them using RNA sequencing. In 1995 they were able to show that it was indeed a white-eye (family Zosteropidae), and closely related to the golden white-eye and the white-eyes of the genus Rukia of Micronesia. The molecular evidence was supported by behavioural similarities to the white-eyes, such as the highly social allopreening and maintaining close contact when roosting.<p>There are two subspecies of Bonin white-eye, the extinct nominate, formerly found in Mukojima and Chichijima, and the southern subspecies, A. f. hahasima, of Hahajima.

Wissenschaftlicher Name

Apalopteron familiare

Autorität

(Kittlitz, 1830)

Ordnung

Passeriformes

Familie

Zosteropidae

Gattung

Apalopteron

Verbreitung und Lebensraum

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.<p>On Hahajima, the only island on which its habitat preferences have been studied, 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.

Zugverhalten

Standvogel

Verhalten

Zugverhalten: Standvogel.

Schutzstatus

Bestandstrend: stabil.

Bestandstrend

stabil