SUNBIRDS: Nectariniidae

PHYSICAL CHARACTERISTICS

Sunbirds are very small birds, 3 to 7 inches (8 to 16 centimeters) long, resembling New World hummingbirds. The males of most sunbird species are brilliantly colored with combinations of iridescent, metallic green, purple, blue and black along with spots and patches of yellow, orange and red. Males of a few species are more drab, as are the females of nearly all sunbird species, although females of some species bear a metallic sheen. Outside of the breeding season, males molt and revert to less gaudy plumage (feathers) resembling that of the female of the species.

Sunbirds can easily be mistaken for the New World hummingbirds, but the sunbirds are strictly Old World birds and are not in any way related to hummingbirds. Sunbirds and hummingbirds are vivid examples of convergence, through adaptive evolution, by which unrelated species come to resemble each other due to similar environmental pressures over long stretches of time. In the case of sunbirds and hummingbirds, feeding on nectar has been the major adaptive molding factor in the two families.

Many single species are confined to some small islands off Africa, India, or in Indonesia. Examples include the Seychelles sunbird, found only on the Seychelles Islands, and the São Tomé sunbird, found on São Tomé.

Sunbirds in the genus Nectarinia have long, thin, downcurved bills for reaching into flowers to sip nectar, much like the bills of hummingbirds and other nectar-feeding bird species among the asity-sunbirds (family Philepittidae) and Hawaiian honeycreepers. Species in genus Anthreptes, considered the most primitive of the genera, have short, straight bills and chiefly feed by gleaning (plucking) insects from leaves, although they add nectar and fruits to their diets. Species of the genus Aethopyga have short bills and are among the most brilliantly colored animals alive. Species of genus Arachnothera, the spiderhunters, have low-key green, yellow, and gray plumage and most have very long, downcurved bills.

GEOGRAPHIC RANGE

Sunbirds live in tropical Africa, Madagascar, tropical Southeast Asia, Indonesia, Philippine Islands, Australia, and New Guinea.

HABITAT

Sunbirds can be found in lowland and mountain tropical rainforest, savanna with open woodlands, gallery forests (along rivers in dry country), thornscrub, and mangrove.

DIET

Sunbirds eat mostly nectar but also fruit, insects, spiders and related creatures.

BEHAVIOR AND REPRODUCTION

Sunbirds are active, energetic creatures. Individuals may forage alone, in monogamous (muh-NAH-guh-mus) pairs (with just one mate), or in groups. Some species, among them the olive sunbird, collared sunbird, and Bates' sunbird, forage in groups in the canopies of dense primary tropical forest.

SPIDERHUNTERS

The ten species of spiderhunters are an obscure, little-studied group of small, mostly arboreal birds scattered through the tropical forests of Southeast Asia and some of the Indonesian islands. They feed on spiders and insects. Beaks of all the spiderhunters are thin and downcurved, more or less like those of sunbirds, but more robust. The beak of the gray-breasted spiderhunter is so long and robust that it borders on the grotesque.

The most common sort of nest built by sunbirds is oval, purse-like, and hung from a small tree branch. Sunbirds form monogamous pairs to mate and breed. The female constructs the nest and incubates the eggs, while both sexes care for the chicks. The female lays two or three eggs.

SUNBIRDS AND PEOPLE

Sunbirds are not harmful to humankind in any way. They are a delight wherever they live, and a tourist draw for birdwatchers and people interested in exotic things.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists two species of sunbird as Endangered, facing a very high risk of extinction; four as Vulnerable, facing a high risk of extinction; and eight as Near Threatened, in danger of becoming threatened with extinction.

RUBY-CHEEKED SUNBIRD (Chalcoparia singalensis): SPECIES ACCOUNTS

Physical characteristics: The adult body length is around 3.9 to 4.3 inches (10 to 11 centimeters). The bill is short and not downcurved. The male is iridescent green above, yellow below, with vivid crimson patches on the cheeks. Females and young are duller but the female shares the male's orange throat.

Geographic range: Northern India to northern Indochina, Sumatra, Java, and Borneo.

Habitat: Lowland and mountain tropical rain forest; also open forest, scrub forest, gardens.

Diet: Ruby-cheeked sunbirds feed on nectar and insects.

Behavior and reproduction: Ruby-cheeked sunbirds forage in tropical forests, in the canopy and at mid-level, usually in groups of five to ten. They also visit gardens for foraging. The call is a loud "chirp." Breeding follows the usual pattern among sunbirds: monogamous breeding pairs, purse-like nests, female incubating eggs, and both parents caring for the chicks.

Ruby-cheeked sunbirds and people: There is little significant interaction between ruby-cheeked sunbirds and humans, other than human appreciation of the exotic beauty of this and other sunbird species.

Conservation status: This species is not threatened. ∎

PURPLE SUNBIRD (Cinnyris asiaticus): SPECIES ACCOUNTS

Physical characteristics: Adult body length is 3.9 inches (10 centimeters). Males are dark, glossy bluish purple above, with yellowish underparts. The female is less colorful, with a yellow and gray upper body, but has yellow underparts much like the male's. The beak is thin and downcurved and the tongues are tubular with brushy tips (of flesh), because of their adaptation to a diet of mainly nectar.

Geographic range: These birds live from Pakistan through India to Southeast Asia. This is the most common sunbird species in India.

Habitat: Purple sunbirds live in forests, often visiting gardens.

Diet: These sunbirds eat nectar and insects.

Behavior and reproduction: Purple sunbirds forage for nectar, insects, and related creatures in forests and often visit gardens to seek out nectar. The call can be rendered as a humming "zit zit" and "swee swee." Breeding follows the usual pattern among sunbirds: monogamous breeding pairs, purse-like nests, female incubating eggs, and both parents caring for the chicks.

Purple sunbirds and people: There is little significant interaction between purple sunbirds and humans, other than human appreciation and awe of these jewel-like birds.

Conservation status: These birds are not threatened. ∎

GOLDEN-WINGED SUNBIRD (Drepanorhynchus reichenowi): SPECIES ACCOUNTS

Physical characteristics: Adult male body length is about 4.7 inches (12 centimeters) without the tail, which adds another 4.7 inches (12 centimeters). The tail and wings are bright yellow, the shoulders are dark gray, the dark gray extending to the nape and throat, while the head and downturned beak are lighter gray. The tail is long and ends in two long, very narrow parallel feathers.

Geographic range: These birds are found in East Africa; Kenya, Tanzania, and Uganda.

Habitat: Golden-winged sunbirds live in grassland, bamboo thickets, and tropical mountain forest.

Diet: These sunbirds eat mainly nectar, with some insect fare.

Behavior and reproduction: Golden-winged sunbirds are of special interest to ethologists (scientists who study animal behavior) because a typical foraging flock of related individuals guards its major source of nectar outside the breeding season, when nectar is their main food source. They actively chase other birds, including others of their own species, away from the nectar source, usually a patch of shrubbery or other plants bearing flowers and nectar. The effect is to increase the amount of nectar available in a flower patch by letting it collect throughout the day, undisturbed by other nectivores (animals that feed on nectar). The more nectar per flower, the less foraging time the sunbirds have to spend on sipping enough for their needs. In addition, the sunbirds wait for nectar in a flower patch to accumulate to a level adequate for feeding the group before making the sipping rounds.

Breeding follows the usual pattern among sunbirds: monogamous breeding pairs, purse-like nests, female incubating eggs, and both parents caring for the chicks.

Golden-winged sunbirds and people: There is little if any interaction between golden-winged sunbirds and humans. They are valuable to science for their resource-defending behavior, the study of which promises more understanding of avian biology and behavior.

Conservation status: These birds are not threatened. ∎

FOR MORE INFORMATION

Books:

Cheke, Robert A., Clive E. Mann, and Richard Allen. A Guide to the Sunbirds, Flowerpeckers, Spiderhunters, and Sugarbirds of the World. New Haven, CT: Yale University Press, 2001.

Christy, P., and W. V. Clarke. Guide des Oiseaux de São Tomé & Príncipe. Libreville, Gabon: Ecofac, 1998.

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

Kavanagh, James. African Birds. Chandler, AZ: Waterford Press, 2001.

Strange, Morten. Birds of Southeast Asia: A Photographic Guide to the Birds of Thailand, Malaysia, Singapore, the Philippines and Indonesia. London: New Holland, 1998.

Strange, Morten. A Photographic Guide to Birds of Malaysia and Singapore: Including Southeast Asia, the Philippines and Borneo. Singapore: Periplus, 2000.

Sinclair, Ian, et al. Illustrated Guide to the Birds of Southern Africa. Princeton, NJ: Princeton University Press, 1995.

Stevenson, Terry. Field Guide to the Birds of East Africa: Kenya, Tanzania, Uganda, Rwanda, Burundi. Princeton, NJ: Princeton University Press, 2001.

Van Perlo, Ber. Birds of Western & Central Africa. Princeton, NJ: Princeton University Press, 2003.

Periodicals:

Gill, F. B., and L. L. Wolf. "Economics of Feeding Territoriality in the Golden-winged Sunbird." Ecology 56 (1975): 333–345.

Irwin, M. P. S. "The Genus Nectarinia and the Evolution and Diversification of Sunbirds: An Afrotropical Perspective." Honeyguide 45, no. 1 (1999): 45–58.

Irwin, M. P. S. "What Sunbirds Belong to the Genus Anthreptes?" Honeyguide 39, no. 4 (1993): 211–215.

Kennedy, R. S., P. C. Gonzales, and H. C. Miranda. "New Aethopyga Sunbirds (Aves: Nectariniidae) From the Island of Mindanao, Philippines." Auk 114 (1997): 1–10.

Pyke, G. H. "The Economics of Territory Size and Time Budget in the Golden-winged Sunbird." American Naturalist 114 (1979): 131–145.

Showler, D. A., and P. Davidson. "The Socotra Sunbird Nectarinia balfouri." Sandgrouse 17 (1996): 148–150.

Web sites:

Sugarbirds, Flowerpeckers, Sunbirds and Spiderhunters of the World (photo gallery). http://www.camacdonald.com/birding/Sampler7_SunbirdsFlowerpeckers.htm (accessed on July 20, 2004).