Fairy Bluebirds and Leafbirds: Irenidae

views updated

FAIRY BLUEBIRDS AND LEAFBIRDS: Irenidae

COMMON IORA (Aegithina tiphia): SPECIES ACCOUNTS
ASIAN FAIRY BLUEBIRD (Irena puella): SPECIES ACCOUNTS

PHYSICAL CHARACTERISTICS

Fairy bluebirds and leafbirds range in length from about 6 to 11 inches (13 to 30 centimeters), and weigh, on average, about 0.5 to 2.8 ounces (13 to 80 grams). Their toes are relatively small for their size, and their ankle bones are short and thick. The birds' bills are fairly heavy. The fairy bluebird adult males are the color of an ultramarine to a turquoise, or cobalt blue, with the color going down over the lower tail. The rest of the bird is the color of black velvet or deep blue. Females are duller in color than the males, as are the juvenile birds. However, the juveniles differ from the females due to their lack of a bright red iris. In leafbirds, both male and female have very bright green plumage, feathers. Fairy bluebirds and leafbirds are similar to bulbuls in that many of their feathers are shed when they are handled.

The four iora species have patterns with various shades of yellow and dull green, and black in some males. All but the great iora have dark wings contrasted with white bars in both males and females. The eyes are pale gray. Their beaks are black, thin, and not curved. Nonbreeding male ioras have dull plumage.

Fairy bluebirds and leafbirds share two characteristics with bulbuls. Those similarities are that the upper tail coverts, feathers at the base of the tail, are long and fluffy, and the patch of hair-like feathers that have no veins on the nape of the neck. They also share the vocal ability that most bulbuls have.

GEOGRAPHIC RANGE

Fairy bluebirds and leafbirds can be found throughout Asia, in southern China, Indochina, the Malay Peninsula, the Greater Sundas, and in India. Some species have limited distribution such as the Marshall's iora that is found only in tropical Pakistan and northwestern India, or the yellow-throated leafbird that can be found only on the western Philippine island of Palawan and some its tiny satellite islands. The Philippines mark the eastern boundary for these birds.

HABITAT

None of the fairy bluebirds live on the ground or in the undergrowth, but instead strictly inhabit tree canopies of deciduous or coniferous forests, in the higher branches. Some leafbirds do visit gardens regularly. The ioras have a wider range of dwellings and might be found on beaches or mangrove swamps to secondary forests. They are also found in gardens or orchards.

DIET

In general, the birds of this family are fruit eaters and nectar-feeders, as in the case of the leafbird, though they also eat insects and spiders, as well as eat small fruits such as the oriental mistletoes. Ioras are known to eat fruit, but tend to hunt in pairs for caterpillars, moths, and spiders, moving quickly from branch to branch, and sometimes even hanging upside down in order to find their prey or feed.

BEHAVIOR AND REPRODUCTION

Both ioras and fairy bluebirds roam in flocks. As a rule, they do so with other species. Fairy bluebirds associate with birds that include feeding fruit pigeons and bulbuls. Ioras associate with those of a similar size that are also insect eaters. Leafbirds are also nomadic except during the breeding season, but usually travel in smaller groups or pairs. They are known for their aggression toward other birds and are gifted with the ability to mimic other species.

All three of these groups of birds are monogamous (muh-NAH-guh-mus), meaning that they have only one partner during the breeding season, and also exercise territorial rights during that time. They exhibit differences in the months they breed, varying with location. The common iora nests from May to September, Marshall's iora only breeds from June to August in the drier ranges of Pakistan and northwest India.

Ioras have a mating ritual during which the male becomes a brightly colored vision in contrast to his normal state of being inconspicuous. The male begins by chasing the female, then perches with his wings lowered and proceeds to fluff up his lower back feathers. The male then lifts the tail and gives its call, which consists of hissing sounds. It jumps back and forth above its perch with the white back feathers fluffed, and then goes back to its perch slowly in a spiral while making a sound like a cricket or tree frog.

Fairy bluebirds build their nests at least 16.5 feet (5 meters) up in the forks of trees and the lower canopy. It is a rough sort of platform made of long, thick twigs hidden with a cover of roots and moss, with an open cup formed in the middle for the eggs. The clutch is two or three eggs that are greenish white to olive-gray, with brown splotches, and a grayish purple often coming together into a cap over the wide end of the egg. Observations have indicated that only the female builds the nest, though both male and female parents feed the young.

FAIRY BLUEBIRDS, LEAFBIRDS, AND PEOPLE

Ioras provide humans with a natural form of insect control. Leafbirds pollinate flowering trees, and spread the seeds of the parasitic oriental mistletoe between trees.

Leafbirds are well-represented in art, with the Chinese depicting them since at least the fifteenth century. Many other varieties of this family have been prized as well for their beauty and were shipped commercially in the late nineteenth and early twentieth centuries. Before World War II, India was the largest supplier of these birds. By the 1950s and 1960s, Thailand, and then Indonesia were major sources. By the 1990s, China exported them until a ban was imposed on caged birds in 2001. Indonesia then played the key role in their export. Their tendency to fight with other birds has made them unsuitable for mixed groups of species.

CONSERVATION STATUS

The green iroa, Sumatran blue-masked leafbird, and lesser green leafbird are listed as Near Threatened, in danger of becoming threatened with extinction. The Philippine leafbird is considered Vulnerable, facing a high risk of extinction, due to forest destruction resulting in loss of habitat. In general, many of the species have suffered some loss of habitat, though minimal, and with a wide distribution they are not threatened on a global level.

COMMON IORA (Aegithina tiphia): SPECIES ACCOUNTS

Physical characteristics: The common iora ranges in length from 5.5 to 6 inches (13 to 17 centimeters), and has a weight that averages about a 0.5 ounces (13.5 grams). The females are olive-green on their upperparts, with dull yellow underparts, foreheads, and eyebrows, with olive-green crowns. The males have dark green to black upperparts, very bright yellow underparts, black wings with white bars, dark tails, and black crowns.

Geographic range: The common iora can be found throughout almost the entire Indian subcontinent, Sri Lanka, southern Yunnan and southwestern Guanxi in China, all of Myanmar, Indochina, and the Malay Peninsula, Sumatra, Java, Borneo, and Palawan.

Habitat: The common iora dwells in open woodlands, secondary forests, gardens, orchards, mangroves, and beach forests.

Diet: Common ioras are omnivores, but have a diet consisting of arthropods which includes spiders, moths, caterpillars, and other similar insects that can be found on leaves. They also eat some fruit.

Behavior and reproduction: When they are not breeding, common ioras tend to travel in small flocks, or pairs, as they continually hunt for their food. Contact among the birds is made through vocalizing often. Their songs and whistles are both distinctive as well as pleasant.

The common iora is monogamous. The male has specific behaviors for courtship as described in the earlier section on the family of fairy bluebirds, leaping 3.3 to 6.6 feet (1 to 2 meters) above its perch, then gliding down with erect feathers, and taking on the appearance of a sphere-like shape. The nest is deep and cup-shaped, with a clutch of two to four eggs that are white with a pink tint and brown or purple-colored blotches.

Common ioras and people: The common iora provides insect control in fruit orchards by feeding on caterpillars and other harmful insects.

Conservation status: This species is not threatened. Due to the creation of gardens and orchards, it is most likely that the common iora has widened its habitat range. ∎

ASIAN FAIRY BLUEBIRD (Irena puella): SPECIES ACCOUNTS

Physical characteristics: The Asian fairy bluebird has a sturdy build, with a length of 10 inches, (25 centimeters), and a weight of 2.5 ounces (75 grams). The male has black under parts, wings, and tail, with ultramarine blue upperparts and feathers under the tail. Females are dark turquoise-blue all over with black flight feathers. Both male and female have red eyes.

Geographic range: The Asian fairy bluebird can be found on the coast of southern India, in the eastern Himalayas, Myanmar, Yunnan, Indochina, Malay Peninsula, Java, Sumatra, Borneo, and the western Philippine island of Palawan.

Habitat: Asian fairy bluebirds can be found living primarily in primary and tall secondary forests.

Diet: Asian fairy bluebirds are omnivores, eating insects and nectar. Their primary source of food is fruit, especially preferring figs.

Behavior and reproduction: These birds can be found in flocks of up to thirty birds, and dwell mostly in the upper parts of the forest. They will bathe in streams, only to return to ascend again, returning to the higher locations. Asian fairy bluebirds are known for their melodious whistle.

Asian fairy bluebirds and people: These birds have no special significance to humans.

Conservation status: Asian fairy bluebirds are not threatened due to their broad distribution. Some populations are at risk, however, because of forest destruction in some areas. ∎