Behavior

White-eyes are highly social birds, often seen huddling together. Foraging, bathing (including bathing in dew on leaves), resting, and roosting activities are governed by social factors. Sunning is done individually. Allopreening (mutual preening) occurs between sexual pairs, parent-offspring, young siblings, and prospective partners in pair formation, which starts as early as one month of age. Silvereyes in Australia normally mate for life and remain in pairs in winter flocks. On Heron Island in the Great Barrier Reef, older birds tend to stay near their summer territories while younger birds range widely in flocks. They continue to improve their foraging skills until their third year. They exhibit ritualized forms of aggression, such as wing fluttering and bill clattering, leading to dominance hierarchies within flocks. Dominance contributes significantly to differential survival and reproduction among individuals. Courtship involves horizontal wing quivering and sometimes motions of nest building without nest material. Males sing for up to 20 minutes at dawn throughout the breeding season. Some also sing for a shorter period at dusk and sporadically through the day. Their melodious and rich warbles are similar across the different species. Males also have a soft courtship warble and both sexes have a long-

drawn plaintive call and short calls. Incessant exchanges of high-pitched short calls that characterize migratory flocking and take-off may also be heard in the predawn sky during the migration. In addition, they have a distinctive alarm call, a roosting call, a soft huddling call, a begging call, variable aggressive calls, and a distress call.

Continental species in the temperate region migrate to warmer areas in winter. Zosterops erythropleura, a chestnut-flanked species, breeds along the lower Amur and Ussuriland in the high latitudes that no other species of the family has reached. It migrates a distance of 2,200 mi (3,500 km) to winter in mountain forests of Myanmar, Thailand, and southern China. In Australia, for a long time Sydney ornithologists were familiar with yellow-throated and fawn-flanked sil-vereyes in summer and gray-throated and chestnut-sided sil-vereyes in winter, and thought that silvereyes had different plumage in summer and winter, which was accepted as fact since this species had two molts a year, spring and autumn. Allen Keast found that only some members of the Sydney population had brown flanks in winter and that in the aviary individual birds did not change plumage color over an entire year. He also noted that the brown-flanked birds did not appear until late April, long after the molt of the local birds, and thus concluded that the gray-throated, brown-sided birds were migrants from Tasmania and did not breed locally in the Sydney area. Large-scale banding of silvereyes started in 1958, and soon one bird banded in Sydney became the first of many to be recovered across Bass Strait to prove the migration theory. Silvereyes are easy to trap and have become the most popular species among the Australian bird banders. Between 1953 and 1997, 285,345 silvereyes were banded, yielding long-distance recoveries of up to 1,000 mi (1,600 km) and longevity of up to 11 years.

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