WHISTLERS: Pachycephalidae

PHYSICAL CHARACTERISTICS

Whistlers range from 5 to 11 inches (12.5 to 28 cm) in length and weigh 0.8 to 3.84 ounces (12.5 to 110 grams). They have sturdy bodies and large, round heads, giving this family of birds the name "thickheads." They have small, round wings and strong feet and legs, making them more suited to hopping about on tree branches, rather than flying and diving. Their bills are thick and strong with a hook at the tip, allowing them to grasp insects and other small invertebrates. Some species have powerful jaws and bills that are shorter and fuller so that they can pry up bark to look for insects. Other species have small crests on the backs of their heads.

Most species are subdued brown, reddish brown, gray, or olive-gray for both males and females. However, there are some species that have bright markings in yellows, whites, and reds for males; females have duller coloring. Young birds are usually reddish brown.

GEOGRAPHIC RANGE

Whistlers are found in Southeast Asia, the Philippines, Indonesia, Micronesia, New Guinea, New Zealand, Australia, and islands in the southwest Pacific. New Guinea and Australia, in particular, have the greatest number of different species in their regions.

HABITAT

Some whistler species live in dense rainforests in the tropics or the forests and woodlands of temperate zones, and others occupy mangrove swamps and mallee, or eucalyptus (yoo-kah-LIP-tus) trees that grow in semi-arid regions. The sandstone shrike-thrush builds its nest on sandstone escarpments, steep cliffs, that have few trees.

DIET

Whistlers eat insects, larvae (LAR-vee), and small invertebrates, animals without a backbone. The white-breasted whistler includes small crabs and mollusks in its diet. The large shrike-thrushes eat small vertebrates, animals with a backbone, baby birds, and eggs. Some birds will take fruit, especially berries, and the mottled whistler eats fruit exclusively.

BEHAVIOR AND REPRODUCTION

Members of this family are called whistlers because their songs are composed of whistling sounds, with each species having a distinctly different variation. The song of the crested bellbird is deep and bell-like. Pitohuis often sing duets. When startled by loud noises like thunder, whistlers will burst into song. They also sing during mating season to mark their territories.

Whistlers forage for insects alone by looking among leaves and bark. Shrike-tits forage in small groups, and pitohuis will congregate with birds of different species or families that look like they do. The crested bellbird and the larger shrike-thrushes find food on the ground and will stand and pounce. The shrike-tits and the ploughbill remove bark from branches and look underneath for insects.

These birds generally stay in their territories. Those along the southeastern coast of Australia, however, will migrate to lower elevations during the winter.

Whistlers choose mates in the dry season and rear their young as the rainy season begins in the Southern Hemisphere's spring and summer. Those species that live in arid areas, however, will mate whenever climate conditions permit.

Males and females share nest-building and child-rearing duties, although this practice varies among species. Some males will even incubate, or sit on the eggs until they hatch. Females in other species will build the nest and incubate the eggs, but will receive help feeding chicks from males and, sometimes, from other members of a group who help with child rearing. This is called cooperative breeding.

Cup or bowl-shaped nests, made from twigs and bark, are built in a tree branch or shrub. In regions with tall forests, the nest can be as high as 33 feet (10 meters) from the ground. In more arid regions where tree growth is limited, the nests will be placed in shrubs and low vegetation within 3 feet (100 centimeters) of the forest floor. The sandstone shrike-thrush, which lives in a region with few trees, will build its nest on a cliff edge or in a rock crevice. Oddly, the crested bellbird places paralyzed caterpillars along the rim of the nest when the eggs are incubated.

Generally, whistlers have only one brood, or set of eggs hatched at the same time, each season, although some species will try to raise two or three. Females lay two to four speckled or blotched eggs that are incubated fourteen to twenty-one days and fed in the nest for fourteen to twenty-one days.

WHISTLERS AND PEOPLE

The whistlers' songs have made them favorites of bird watchers. Some species like the gray shrike-thrush will even build its nest among the foliage of potted plants outside homes.

CONSERVATION STATUS

The piopio is Extinct, or died out. The Sangihe shrike-thrush is Critically Endangered, facing an extremely high risk of extinction, due to loss of its forest habitat on the tiny Indonesian island of Sangihe.

The yellowhead is Vulnerable, facing a high risk of extinction, because its population in New Zealand has been preyed upon by stoats (ermines) that were introduced into the birds' territory. Stoats have eaten not only eggs and newly-hatched birds, but adult females as well.

POISONOUS BIRD

In 1989, biologist Jack Dumbacher recorded the first instance of natural toxicity, or poison, in a bird. The bright orange-and-black hooded pitohui and four others in this genus (JEE-nus), group of related birds, have a neurotoxin, or poison that affects the nerves, in their skin, feathers, and flesh. This neurotoxin produces numbness when touched and is the same poison found in the poison dart frogs of Central and South America. Scientists have not been able to figure out how the birds, or the frogs, make the poison, or how these animals are able to survive with the poison in their systems.

The red-lored whistler of Australia, the white-bellied pitohui of New Guinea, and the Tongan whistler are Near Threatened, in danger of becoming threatened with extinction, due to habitat loss and foreign animals that were introduced into whistler territory.

GOLDEN WHISTLER (Pachycephala pectoralis): SPECIES ACCOUNTS

Physical characteristics: Also called the golden-breasted whistler, this bird is small, measuring 5.9 to 7.5 inches (15 to 19 centimeters) and weighing 0.8 to 0.96 ounces (21 to 28 grams). It has a black bill, head, and band below a white throat. The back and wings of the male are olive green, and the undersides are sulfur yellow. The female has a muted olive gray body with a pale yellow belly. Both sexes have reddish brown eyes. Young birds of both sexes are reddish, changing to the muted colors of the female. When they are fully mature, male birds will display bright plumage.

Geographic range: Over seventy subspecies of golden whistlers live in Indonesia, New Guinea, Tasmania, and the southern and eastern coasts of Australia, as well as small Pacific Islands such as Fiji and the Solomon Islands.

Habitat: Golden whistlers have adapted to a variety of habitats that support trees, ranging from the dry mallee to the wet mangrove swamps. Occasionally, these birds will occupy trees in orchards and parks. Golden whistlers nest below 6,900 feet (2,100 meters).

Diet: This species eats mainly insects, spiders, and berries.

Behavior and reproduction: Golden whistlers mate in the spring of the southern hemisphere, September to January, and only have one brood. Both the male and the female build a cup-shaped nest from bark and twigs, lashed together with spider webs and lined with fine grass. Placed in the fork of a branch or nestled deep in a shrub, the nest can be as high up as 20 feet (6 meters). The female lays one to three spotted eggs of varying colors. The eggs can be cream, buff, salmon, or pale olive green with spots or blotches of greenish brown, or reddish brown, gray, or lavender. Sometimes, these blotches collect around the larger end of the egg like a cap. Both parents incubate the eggs, usually fourteen to seventeen days. The young birds are fed by their parents for ten to thirteen days.

This species forages among tree branches in the middle story of the forest canopy, only searching the lower level when necessary. Sometimes, golden whistlers will hawk, or dive, for insects they see, but usually they settle on a branch and glean insects and berries from their perches.

These birds are quiet, except when mating, and are not social, living alone or with a mate. Their song is melodious "wi-wi-wi-tu-whit." Generally, they stay within their territories, though some southeastern Australian birds will migrate to the north or west during the winter or descend to lower elevations.

Golden whistlers and people: The golden whistler is appreciated by bird watchers.

Conservation status: Though this species was once quite common, it is now a protected bird in some areas of Australia and efforts are being made to ensure that these birds can increase their population numbers.

VARIABLE PITOHUI (Pitohui kirhocephalus): SPECIES ACCOUNTS

Physical characteristics: A medium-sized bird, the variable pitohui is 9 to 10 inches (23 to 25.5 cm) long and weighs 3 to 3.5 ounces (85 to 100 grams). It has a black head and wings, a reddish back, an orange breast and belly, and black legs. This general coloring, however, varies among its twenty subspecies.

Geographic range: This species can be found in New Guinea and neighboring islands.

Habitat: The variable pitohui nests in thick undergrowth at the edge of forests up to 4,950 feet (1,500 meters). It can even live in forests that have been greatly disturbed.

Diet: This species eats insects and berries.

Behavior and reproduction: Though it generally hides in dense vegetation with its mate, the variable pitohui will forage with other birds, including many that aren't its own species. Its song is musical and pleasant. Mated pairs will often sing duets together. Little is known about the mating behavior of this species.

The variable pitohui and people: This bird has been rarely hunted for food because of its unpleasant taste. In some cases, it is extremely poisonous.

Conservation status: The variable pitohui is not in danger of dying out. However, it is common in some areas, and rare in others. ∎

FOR MORE INFORMATION

Books:

Higgins, P. J., and J. M. Peter, eds. Handbook of Australian, New Zealand and Antarctic Birds. Vol. 6, Pardalotes to Shrike-thrushes. Melbourne: Oxford University Press, 2003.

Perrins, Christopher. Firefly Encyclopedia of Birds. Richmond Hill, Canada: Firefly Books, 2003.

Robbins, Michael. Birds (Fandex Family Field Guides). New York: Workman Publishing Company, 1998.

Schodde, R. Directory of Australian Birds: Passerines. Collingwood, Australia: CSIRO, 1999.

Simpson, K., and N. Day. A Field Guide to the Birds of Australia. Ringwood, Australia: Penguin Books Australia Ltd., 1996.

Weidensaul, Scott. Birds (National Audubon Society First Field Guides). New York: Scholastic Trade, 1998.