Zostérops du Japon

Identification

The warbling white-eye is olive green on its back, from anterior to posterior, and is pale green on its underside. Its feet, legs, and bill range from black to brown. It has a green forehead and a yellow throat. The white-eye has rounded wings and a long, slender bill – both of which indicate this bird to be very acrobatic. Its wings are dark brown but outlined in green. Like other white-eyes, this species exhibits the distinctive white eyering that gives it its name (mejiro, as the bird is known in Japan, translates to "white eye"). Adults range from 4 to 4.5 in (10 to 11 cm) in length, and weigh between 9.75 and 12.75 grams.

Taxonomie

The warbling white-eye was described by the ornithologists Coenraad Jacob Temminck and Hermann Schlegel in 1847 from a specimen collected in Japan. They coined the binomial name Zosterops japonicus.<p>The English name "Japanese white-eye" was formerly used for Zosterops japonicus and what are now the Philippine subspecies of Z. japonicus were treated as a separate species, the "mountain white-eye" Z. montanus. A molecular phylogenetic study published in 2018 found that Z. montanus and several subspecies of Z. japonicus were conspecific, and they were therefore lumped together. They were placed in Z. japonicus Temminck &amp; Schlegel, 1845 as this has priority over Z. montanus (Bonaparte, 1850). The new English name "warbling white-eye" was introduced for the combined taxa. At the same time, several other subspecies of the former Z. japonicus were split off into their own separate species, Swinhoe's white-eye Z. simplex.<p>There are 15 recognised subspecies many of which are island endemics:

Nom scientifique

Zosterops japonicus

Autorité

Temminck & Schlegel, 1847

Ordre

Passériformes

Famille

Zostéropidés

Genre

Zosterops

Répartition et habitat

The warbling white-eye is found in Japan, Korea, Taiwan, eastern China, and the northern Philippines. Migratory populations of the bird spend winters in Burma, Thailand, Hainan Island, and Vietnam. The white-eye is widespread and common in Japan, considered one of the more dominant bird species.<p>In spring 2018 there were several sightings of Japanese white-eyes in Southern California, with confirmed breeding in San Diego County as of 2019. However, in 2019 the California birds were reclassified as belonging to a newly designated species, Swinhoe's white-eye. The dominant white-eye population in Taiwan has similarly been reassigned to Swinhoe's.<p>The warbling white-eye, originally introduced in O’ahu in 1929, has rapidly expanded its population and can now be found on every island of Hawaii; the climates of these islands range from tropical rain forests to deciduous forests. After subsequent releases and natural range expansion (enlargement of the area it occupies), the white-eye was determined to be the most abundant land bird on the Hawaiian Islands as early as 1987. It has become a vector for avian parasites that are now known to adversely affect populations of native birds such as Hawaiian honeycreepers, as well as spreading invasive plant species through discarded seeds.

Comportement

This bird species is rarely found on the ground. It is a very sociable species that may form flocks with other species, in which the birds form groups to forage during flight; white-eyes only flock with birds of other species outside of the breeding season. Allopreening – the art of cleaning, grooming, and maintaining parts of the body – is extremely common. Interspecific allopreening (between different species) has been observed in captivity. While sociable, however, the white-eye typically forms monogamous relationships with mates – it has only one mate at any one time.<p>Social hierarchy in a flock is established through physical displays. Some of these displays are not sex dependent, such as wing flicks exposing the underwing, wing flutters and vibrations, as well as open beak displays and beak snaps (rapid shutting of the beak to make a snapping noise). During breeding seasons, however, males establish territories via the sex-specific activity of singing loudly. Males will fend off intruders of the same species, yet will allow other species of birds to nest inside of their territory.<p>Pairs of individuals, generally monogamous, choose a location for the nest between 1 and 30 meters above ground level. Construction of the nest lasts 7–10 days on average, and a variety of nesting material may be used (living and non-living); spider webs, moss, lichens, and mammal hair are all examples of building media that the birds employ. When building nests, they often steal material from the nests of other birds. Nests tend to be cup shaped, with a diameter of 56.2 mm and a depth of 41.7 mm. The majority of nests are only used once, but some may be used up to three times in any given season.<p>The species is omnivorous, living on a diet of fruit from several species of flowering plants, various types of insects, and nectar at all levels of foliage. It feeds on insects by searching the leaves of flowers and scouring tree bark for larvae. Consequences of its diet include regulation of local insect populations and dispersal of seeds; however, the white-eye's seed-dispersal ability does not seem to be significant in Hawaii.

Conservation

Pour se rétablir et se maintenir, les espèces indigènes doivent retrouver une masse juvénile et une longueur de bec normales, ce qui nécessite un retour des ressources alimentaires à leur niveau antérieur. Des éléments étayent l'hypothèse qu'un oiseau introduit, comme le Zostérops du Japon, est responsable de la pénurie alimentaire. La maîtrise de ses effectifs est donc essentielle au rétablissement des oiseaux indigènes d'Hawaï. Il est indispensable de déterminer le statut de ces derniers ; ceux reconnus comme menacés pourraient bénéficier de la désignation d'un habitat essentiel. En 1980, un programme d'éradication du Zostérops oriental en Californie a combiné capture au filet japonais et tir, une méthode qui s'est révélée la plus efficace parmi celles étudiées. La faisabilité et l'applicabilité de l'éradication à d'autres oiseaux exotiques envahissants restent à établir, mais cette option pourrait être envisagée pour le Zostérops du Japon dans les îles hawaïennes. Son rôle écologique actuel, notamment comme disperseur de graines et pollinisateur, étant encore mal compris, des études supplémentaires sont néanmoins nécessaires avant toute mesure radicale.

Tendance de la population

unknown