Vangas: Vangidae

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VANGAS: Vangidae

RUFOUS VANGA (Schetba rufa): SPECIES ACCOUNT

PHYSICAL CHARACTERISTICS

Vanga species look so different from one another that only ornithologists, scientists who study birds, and DNA comparisons have been able to find enough similarities among them to realize that they are related species within one family. Males and females of most vanga species have different colors and patterns. Colors among species vary enormously. The three closely related species Lafresnaye's vanga, Van Damm's vanga, and Pollen's vanga, are similar in appearance, both males and females sporting differing patterns of sharply defined black, white, and gray. The head may be entirely black or only partly so, the rest white. Bernier's vanga is simple in design but striking in appearance, with a glossy black body and head, white eye, and blue bill and legs. The female outshines the male, her entire coat being a bright red-brown with narrow, black streaks. Perhaps the most beautiful and memorable of all vanga species is the blue vanga, with its vivid ultramarine blue head, wings, and bill, white underside, white eyes enclosed by a black mask, and a blue and black tail.

As a whole, vangas are small birds. The largest species are the sickle-billed vanga, with a beak-to-tail length of 12.5 inches (32 centimeters) and a body weight of slightly over 4 ounces (114 grams); the helmet vanga, with a length of 12 inches (31 centimeters) and a body weight of 3.8 ounces (108 grams); and the hook-billed vanga, with a length of 11 inches (29 centimeters) and a weight of 2.5 ounces (67 grams). The smallest species are the red-tailed vanga and Chabert's vanga, both 5.5 inches (14 centimeters) long and weighing only 0.5 ounces (14 grams), and the blue vanga, 6 inches (16 centimeters) long and weighing just under 1 ounce (28 grams). Head-and-body lengths for other species run 8 to 10 inches (20 to 25 centimeters).

The original beak of the ancestral vanga species went through some extreme shape changes in descendant species. The helmet vanga sports a big, casque-like (KASK-like) bill reminiscent of the bills of hornbills or toucans. The sickle-billed vanga has a thin, almost needle-like bill, curved downward, that may reach nearly 3 inches (7 centimeters) in length. The bill of the hook-billed vanga is straight, with a small, downturned hook at the end of the upper bill. Van Damm's vanga, Lafresnaye's vanga, and Pollen's vanga share a very unusual bill type. The bill is thick, strong, deep vertically and narrow horizontally, giving it a distinctive chisel shape, and fit for the chisel-like work of prying bark from trees, prior to yanking insects out of the wood.

GEOGRAPHIC RANGE

Vangas occupy varying ranges in the forested parts of Madagascar, a large island off the southeastern coast of Africa. One species, the blue vanga, is the only species found outside of Madagascar, it also lives on the Comoro Islands between Madagascar and Africa.

HABITAT

All vangas are forest species, and are found in all the major forest types of Madagascar, which includes tropical rainforest along the east coast, tropical deciduous forest (with a rainy and a dry, rainless season) along the west coast, and the so-called "spiny forest" (or xeric [ZEHR-ik] forest) in the arid south. Some species also forage in scrub.

DIET

All vanga species are primarily insectivorous, feeding mostly on insects and related creatures like spiders, although some species add small amounts of fruit to their menus, and some spice up their insect diets with frogs, lizards, snails, mouse lemurs, and young birds.

Vangas consume insects and related creatures by means of four methods: gleaning, or plucking insects off leaves, twigs, branches, and bark while the bird is perching; sally gleaning, or gleaning while flying tight loops about the feeding site; flycatching, in which a bird on the wing snags and eats flying insects; and probing, in which the bird uses its bill to poke under and tear off strips of tree bark to reach insects. A vanga species may use one of these feeding methods, or various combinations.

When handling relatively large prey, too large to be downed in a single gulp, some vanga species engage in "clamping" or "grasping." When clamping, a perching vanga, having caught the prey with its bill, transfers it to one of the perching feet, which holds the prey against the branch. When grasping, a vanga holds the prey in an outstretched foot that is not grasping a branch. In either case, the vanga then tears apart and eats its prey.

Vangas may forage together in mixed-species flocks of two or more vanga species and sometimes including insectivorous bird species of other families, for protection in numbers and for helping one another find food.

BEHAVIOR AND REPRODUCTION

Little is known about reproductive behavior. Mating and raising of chicks for most species takes place from October through January, although breeding times are not known for all vanga species. Two exceptions are the nuthatch vanga and Bernier's vanga, which nest through August and September.

A female lays from one to four eggs. The eggs are variously colored among species. The nests so far observed have been bowl-shaped and built on branches or in forks of branches. The nests are woven from various types of plant materials, such as leaf stalks, twigs, moss, and rootlets. Several vanga species reinforce the weaving with spider webs.

VANGAS AND PEOPLE

No vangas are pest species, since they are confined to forested areas away from agricultural land and have little interaction with humans. In Madagascar's growing ecotourism industry, vangas play a starring role as symbols of the uniqueness of Madagascar's animal life.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists three vanga species as Vulnerable, facing a high risk of extinction, and one as Endangered, facing a very high risk of extinction. The species listed as Vulnerable are the red-shouldered vanga, due to restricted territory and a small population; Bernier's vanga, because of its small population and deforestation; and the helmet vanga, because of limited territory and deforestation. Van Dam's vanga is listed as Endangered due to its very small range and fragmented populations.

RUFOUS VANGA (Schetba rufa): SPECIES ACCOUNT

Physical characteristics: Bill-to-tail length is 8 inches (20 centimeters). The male has a black head, neck, and chest, with blue highlights. The bill is blue-gray, the eyes are dark red, the upperparts are reddish brown and the belly is white. The wings are red-brown and brown. The female is similarly colored, the differences being white cheeks, chin, and throat on the otherwise black head, and a gray collar.

Geographic range: The rufous vanga lives in Madagascar, in rainforest along most of the east coast, and in tropical deciduous forest in the northwest.

Habitat: The rufous vanga prefers undisturbed rainforest from sea level to 5,400 feet (1,800 meters) above sea level, and undisturbed or slightly disturbed tropical deciduous forest.

Diet: The rufous vanga feeds mainly on insects and occasionally on small lizards.

Behavior and reproduction: The rufous vanga picks insects and lizards from branches and tree trunks or flushes them from ground litter. Of the various vanga species, this vanga spends the most time foraging on the ground. Often an individual sits on a low branch for long periods of time, watching for moving prey. The rufous vanga sometimes follows another bird, the white-breasted mesite (family Mesitornithidae). The mesite runs through ground litter, flushing out insects and other small animals for its own feeding, the vanga helping itself to some. It is not a mutually beneficial relationship; the vanga merely takes advantage of the mesite's feeding tactic.

Rufous vangas live in groups of four to eight, and may join in mixed-species feeding flocks with other vangas or with bird species other than vangas. Their voice is melodious, and pairs may sing duets, often punctuated by clacking their bills.

The rufous vanga is one of the few vanga species whose reproductive biology is even partly known. The breeding period runs October through December, and chicks are born November through January. A female lays one to four eggs. A noteworthy aspect of reproduction in this species, seen in other bird families, is "helping behavior." During the breeding season, a nesting site may be occupied by one or two extra individuals in addition to the nesting pair. These "helpers" will fill in for the parents, sitting on the eggs and even feeding and guarding the chicks while the parents are out feeding. Some of the helpers are immature males, recognized as such by their spotted necks.

Rufous vangas and people: Rufous vangas do not interact with humans in any significant way.

Conservation status: A widespead species in Madagascar, the rufous vanga has no special conservation status. ∎

FOR MORE INFORMATION

Books:

Goodman, Steven M., and Jonathan P. Benstead. The Natural History of Madagascar. Chicago: University of Chicago Press, 2003.

Langrand, O. Guide to the Birds of Madagascar. New Haven, CT: Yale University Press, 1990.

Morris, P., and Hawkins, F. Birds of Madagascar: A Photographic Guide. New Haven, CT: Yale University Press, 1998.

Periodicals:

Goodman, S. M., A. F. A. Hawkins, and C. A. Domergue. "A New Species of Vanga (Vangidae) from Southwestern Madagascar." Bulletin of the British Ornithological Society 117 (1997): 5–10.

Graetz, J. "Nest Observations of the Helmet Vanga, Euryceros prevostii." Newsletter of the Working Group on Madagascar Birds 1, no. 2 (1991).

Safford, Roger. "The Helmet Vanga, Euryceros prevostii." Bulletin of the African Bird Club 7, no. 1 (March 2000).

Yamagishi, S., et al. "Extreme Endemic Radiation of the Malagasy Vangas (Aves: Passeriformes)." Journal of Molecular Evolution 53, no. 1 (July 2001): 39–46.