WHITE-EYES: Zosteropidae

PHYSICAL CHARACTERISTICS

The white-eyes are small perching birds that look very similar across the species. They have slightly rounded wings; short, pointed bills; a brush-tipped tongue that has four sides and is bordered with hairs both at the sides and at the tip; and black legs and feet. Some species have a distinct ring of tiny, dense, pure-white feathers around each eye (which appears early in life) that is divided by black feathers found between the eyes and bill. The name "white-eye" was given to the birds because of the silky white rings around their eyes. Eye color ranges from gray to brown. Overall, plumage (feathers) vary in shades of yellow-green. The upperparts of the birds are green to greenish yellow, with a gray upper back in some species. Underparts are yellowish from throat to undertail coverts (small feathers around the base of quills on wings, tail, or other parts of bird) in some species while other species are grayish to white. The color of the sides of the body varies from light gray to dark brown. Males and females are similar throughout the year, although males are larger in some species. In addition, males in some species can be more brightly colored than females when in colder climates.

Their short, thin bill is blackish, slightly decurved, curved downward, and sharply pointed. Legs are grayish to brownish. Fledglings (birds that have recently grown the feathers necessary to fly from the nest) and old birds have a pinkish color, while one-year-old birds are darker in color. Older birds molt (phase after breeding where feathers are shed and later grown back) into longer wing and tail feathers.

Continental species are generally 4.0 to 5.5 inches (10 to 14 centimeters) long, have wingspans of 2.2 to 2.6 inches (55 to 65 centimeters), and weigh between 0.3 and 0.5 ounces (9 and 15 grams). Those living in higher latitudes tend to be larger, while island species also tend to have bills, legs, and bodies that are larger than normal.

GEOGRAPHIC RANGE

White-eyes are found widely in sub-Saharan Africa, southern Asia, New Guinea, Australia, and the smaller islands of the Pacific Islands. They have been introduced in Hawaii and Tahiti.

HABITAT

White-eyes are found in almost every kind of wooded habitat including woodlands, forest edges and canopies (uppermost layer of vegetation of forest, treetops), and bushes within parks and gardens. They are found from sea level to altitudes of about 9,800 feet (3,000 meters).

DIET

White-eyes have developed highly specialized tongues, which allow them to feed on nectar. They also feed on fruits (especially in winter) and small insects. The birds hunt for insects and spiders by picking them from foliage, probing into small crevices, and sometimes catching them as they fly. They often forage in gardens, orchards, and at the edges of forests. White-eyes are very aggressive when fighting over food. They often flutter their wings and fight in the air with other birds while clattering loudly.

BEHAVIOR AND REPRODUCTION

White-eyes are very social birds, living in wandering groups when not breeding. White-eyes that live on continents migrate regularly to lower latitudes, though sometimes some of the population remains behind. When breeding, they will drop out of the flock, returning after breeding is finished. They are often seen huddling, resting, foraging, bathing, and roosting together, while sunning is done alone. Breeding mates, parent-offspring, young siblings, and prospective partners often preen each other (grooming of feathers with the bill). Wing fluttering and bill clattering are part of their daily activities, which shows rank and status in flocks and decides who has the better chance to reproduce and to survive. Their warbles sound like a rich melody, and are similar across all species. Calls of both sexes are long and sad sounding. Other calls are high-pitched and short, with constant exchanges just before dawn between birds of a flock that are migrating. Other specialized calls include ones for alarm, roosting, begging, huddling, aggression, and distress. Bills are often clattered when aggression is showed.

Courtship involves horizontal wing quivering and some activities that portray nest building (without actually building a nest). Male birds sing for up to twenty minutes at dawn throughout the breeding season, while some singing is also performed at dusk and occasionally throughout the day. Males also have a courtship warble that is softer sounding than the warble sounded during nonbreeding times.

Breeding season usually begins at the start of the summer rains in September or October, and ends six months later. Birds usually mate for life, and breed in small territories. Information about nests and eggs are known for only about half of the species. What is known is that nests are cup-shaped and constructed from plant fibers. They are usually slung from a small fork under the cover of vegetation at any height. The glossy eggs are colored from whitish to pale blue or bluish green, with a few species having spotted eggs. Eggs measure 0.55 by 0.43 inches (14 by 11 millimeters) to 0.79 by 0.59 inches (20 by 15 millimeters). Females lay from one to five eggs, with three being average. The incubation period (time that it takes to sit on eggs before they hatch) last ten to twelve days. Both parents help in the construction of the nest, in incubation, and with feeding of the young. The chicks are about 0.07 ounces (2 grams) when first hatched. They are fed insects at first, but are given fruits at about the time of fledgling. Up to five clutches (group of eggs hatched together) can be laid in one breeding season. A new nest is usually constructed for each clutch. Parents often take care of two clutches at a time. The nestling period (time necessary to take care of young birds unable to leave nest) is eleven to thirteen days.

WHITE-EYES AND PEOPLE

People often keep white-eyes as pets, often for their beautiful songs. They are considered pests in vineyards and orchards in southern Africa and Australia. However, they are also considered beneficial because they eat aphids and other pest insects.

CONSERVATION STATUS

Of the eighty-six species of white-eyes, six species are considered Critically Endangered, facing an extremely high risk of extinction; one species is considered Endangered, facing a very high risk of extinction; and fourteen species are Vulnerable, facing a high risk of extinction. Two species have recently been classified as Extinct.

JAPANESE WHITE-EYE (Zosterops japonicus): SPECIES ACCOUNT

Physical characteristics: Japanese white-eyes have an olive-green back, pale gray underparts, and lemon-yellow throat and undertail coverts. They are about 4.7 inches (12 centimeters) long, and weigh about 0.4 ounces (11 grams). Their wing size is between 20.5 and 25.6 inches (52 and 65 centimeters), and the tail length is between 13.4 and 18.1 inches (34 and 46 centimeters).

Geographic range: Japanese white-eyes are distributed in the Japanese islands, China, Taiwan, Hainan Island, and the Philippines. They have been introduced into Hawaii and Bonin Island.

Habitat: Japanese white-eyes live in broadleaf evergreen forests and deciduous forests on lowlands and foothills of mountains. They are found from sea level to the upper canopies of forests. The birds are also found on cultivated lands and gardens.

Diet: The diet of Japanese white-eyes consist of arthropods (invertebrate animal with jointed limbs), soft fruits, berries, and nectar.

Behavior and reproduction: After breeding season, the birds form small flocks of numerous species, often for foraging. They are partially migratory birds, moving to villages and suburban gardens in the winter. Males sing beautiful songs. Japanese white-eyes breed in the spring, with each breeding pair defending a small nesting territory. Cup-shaped nests are hung from a fork of shrubs. Females lay three to four eggs, which are incubated for about eleven days.

Japanese white-eyes and people: People keep males in cages in order to enjoy their songs. The birds are often found in Japanese literature.

Conservation status: Japanese white-eyes are not threatened. They are common in most parts, but in some remote areas the birds are vulnerable. ∎

FOR MORE INFORMATION

Books:

del Hoyo, Josep, Andrew Elliott, Jordi Sargatal, et al., eds. Handbook of the Birds of the World. Barcelona: Lynx Edicions, 1992.

Dickinson, Edward C., ed. The Howard and Moore Complete Checklist of the Birds of the World, 3rd ed. Princeton, NJ and Oxford, U.K.: Princeton University Press, 2003.

Forshaw, Joseph, ed. Encyclopedia of Birds, 2nd ed. San Diego, CA: Academic Press, 1998.

Harrison, Colin James Oliver. Birds of the World. London and New York: Dorling Kindersley, 1993.

Perrins, Christopher M., and Alex L. A. Middleton, eds. The Encyclopedia of Birds. New York: Facts on File, 1985.