WEAVERS: Ploceidae

PHYSICAL CHARACTERISTICS

Weavers are small, finch-like birds, 4.3 to 10 inches (11 to 25 centimeters) in body length. Weavers are closely related to finches (family Fringillidae) and are sometimes referred to as "weaver finches." Other common names for various genera within the family include queleas, fodies (in Madagascar), bishops, malimbes, mynas, and widowbirds. They are called "weavers" because of the complex, elaborate nests that various species build.

The weaver's beak is short, sturdy, massive, and conical, like a typical finch's beak. The legs are short and resemble those of passerines, except that in some species the feet are larger. The tail is usually long, occasionally as long as the head and body, or even longer, as in the widowbirds.

Weavers could be described as finch-like birds in tropical dress. A few are dull in color, while many others are brilliant and unique, the brightest and most widely seen colors being yellow, orange, and red. Males tend to be more colorful than females. The grosbeak weaver is mainly dark gray with white patches on its forehead and outer edges of the wings. Widowbird species have long, loose, elaborate black tails.

Males of most Ploceidae species change colors during the breeding season, from duller to more vivid, changing back to the duller coat when the breeding season over. The dull phase plumage of the male looks very similar to that of the female, which does not change color. A male red-collared widowbird, in the nonbreeding seasons, is colored light brown on its sides, under parts and head, with dark gray wings, a yellow streak over each eye and yellowish on the cheeks, but the breeding plumage is shiny black with a bright red-orange collar across the throat, extending upwards in two broad red bands near the back of the head, and forming a red cap on the crown.

GEOGRAPHIC RANGE

Weavers live mainly in tropical Africa, as well as Madagascar, southern Asia, and as far east as Borneo and Java. Some species have been introduced into non-native habitats, where they have quickly adapted and flourished.

HABITAT

Habitat preferences among weaver species vary as much as their appearance and behavior. Most prefer open spaces, like grassland with or without scattered trees. The red-billed buffalo-weaver prefers savanna with acacia or baobab trees in east Africa, but is even more partial to areas disturbed by natural forces, such as wild animal herds, or human activities. Some species prefer living close to villages, probably for protection from predators that naturally fear humankind. If the people of the village abandon it, the weavers will desert their nest.

Many weaver species change habitats in the breeding season. The thick-billed weaver, during its breeding season, lives in spreads of grasses, reeds, and papyrus in marshes and rivers. During nonbreeding periods of the year, the species returns to tropical forest.

DIET

The staple food for most weaver species is seeds of various wild grasses, supplemented with insects, spiders, freshwater snails, and fruits. They also help themselves to discarded scraps of human food.

BEHAVIOR AND REPRODUCTION

Weavers are energetic and noisy, especially when gathered together in flocks, which is a large majority of the time for some species and most of the time for a few. Individuals of some weaver species may live alone, but even they periodically form social groups of up to a thousand birds.

Weavers forage in groups, and feed by picking grass seeds, insects, and spiders off the ground, or perching on stalks of grass and yanking seeds from the stalk, crushing all but the hardest seeds with their powerful beaks. Some snag insects in mid-flight. Some weaver species stay more or less in one place, others migrate to greater or lesser degrees.

Weaver voices and songs are long-winded, complex, and vary with circumstances, including displays of aggression, mating, and warning. The song of the red-headed weaver has been transcribed as "chu-tsee-tsi, chu-tsi, tsee-tsi, tswi-tsi-tswee, tzirrrr," morphing into "tchu-thi-tseee-iiiiii-i, swizzzzzzz" or "sizzi-sizzi-sizzi-sizzi."

Reproduction types vary among species and reflect the sort of nest-building used by each. One species, the cuckoo finch, is a brood parasite, similar to cuckoos, cowbirds, and honeyguides. The cuckoo finch lays her eggs in other birds' nests. Consequently, her eggs are treated as family by the receiving birds, allowing the cuckoo to reproduce without caring for her own young. A few weaver species have individual, isolated nests for breeding couples, but most species build colonial nests, either individual nests in one tree, or a giant common nest. Entrances are on the bottom or sides. The communal nest of the social weaver can hold up to three hundred breeding pairs and may reach 10 feet (3 meters) in height and 15 feet (5 meters) in width.

Weavers living in colonies may be polygamous (puh-LIH-guh-mus; one dominant male, several breeding females), polygynous (puh-LIJ-uh-nus; one dominant female, several breeding males), cooperative (two or more males mate with all females, males help care for the young), or monogamous (muh-NAH-guh-mus; one breeding pair), but monogamous pairs may inhabit communal nests. More than one of these systems may be used even within one species. In communities with several breeding pairs, a dominant male mates with the largest number of females possible.

Weavers build nests in large, isolated trees and on power line support towers and windmills. In most species, the male builds the nest or adds onto a communal nest, then invites and entices females to mate with him and move into the nest to raise the young. Large birds of prey may build nests on top of communal weaver nests, partially camouflaging the raptor nest and lending some protection to the weavers. The birds finish the entire structure with a roof of intertwined leaves on twigs, for repelling rain.

The red-billed buffalo-weaver shows both polygamous and cooperative breeding behaviors. In polygamous systems, one male rules and defends up to eight chambers, each with a female and young, in a single large, communal nest. In the cooperative method, two males build and defend nests, and feed the young.

Weavers aggressively defend their nests, not only from predators but also from other members of their own species. The defenders can distinguish nest-family members from strangers of the same species, threatening and driving them off. One or more males are the principal defenders and if they are away from the nest, a female may take over the task of defense.

Female weavers lay two to eight eggs per clutch. The eggs hatch in about fourteen days. In monogamous species, both parents raise the chicks, while in polygamous and polygynous species, adults other than the parents may help care for the young.

WEAVERS AND PEOPLE

It has been suggested that in prehistory, weaver birds may have inspired humans to try their own hand at weaving baskets and cloth. Since most weaver species eat grass seeds, including those of cultivated grasses like rice, wheat, and millet, some of these species have become pests, raiding grain crops. The most pestiferous (pest-like) of all weaver species, is the red-billed quelea. Other weaver species that are more or less sedentary can still cause major local losses of grain crops. These species include the red-headed quelea, the red bishop, and the yellow crowned bishop.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists six species of Ploceidae as Endangered, facing a very high risk of extinction, and seven as Vulnerable, facing a high risk of extinction. The main factor in declining populations of these species is habitat loss by humanity to agriculture and forestry.

VILLAGE WEAVER (Ploceus cucullatus): SPECIES ACCOUNTS

Physical characteristics: Also called the spotted-back weaver and black-headed weaver, the adult body length runs 6 to 7 inches (15 to 17 centimeters), males being larger than females.

During the breeding season, the male is a combination of brilliant yellow on the under parts, and back of the neck and crown, as well as shiny black on the face and bib. The posterior belly may be bright orange-red. The folded wings show alternating streaks and spots of yellow and black, hence the common name, spotted-back weaver. The eyes are orange-red, the beak is black and the legs and feet are brown. The female is less garish, her upper parts olive with dark brown stripes paralleling the body length. The sides are yellow-brown, and the abdomen is whitish with some yellow. Outside the breeding season, the male plumage closely resembles that of the female, whose colors never change.

Geographic range: Africa, western through central to southern and southeastern.

Habitat: Open woods, forest edges, savanna, along rivers and streams, often close to or within villages.

Diet: The village weaver's diet consists of seeds, green vegetation, fruit, ant eggs, and mealworms.

Behavior and reproduction: Mating is at first monogamous, later changing to polygamous, meaning that the birds begin with one mate each and the male eventually finds other females to mate with. After the male has built one nest and attracted and mated with a female, he builds another nest and tries to entice another female to move in. One male may support up to five females in five nests.

Females usually lay two eggs per clutch, which hatch in about fourteen days. The male builds the nest, which holds one female and young, out of grass blades or other vegetation.

Village weavers derive that common name from their frequent habit of nesting near villages in Africa, probably for protection from predators that naturally fear people. Village weavers are well-known for their skills in adapting to new environments, often ones much different from the original and far from home, including the New World, where they were brought by humans. The species has been living on various Caribbean islands for two hundred years. On Hispaniola, village weavers have adapted to near-desert conditions by eating the fruits of the Stenocereus hystrix cactus and depending on them for water.

Village weavers might be frequent hosts for parasitic eggs of the dideric cuckoo. However, village weaver eggs frequently and constantly change color among individual females. Part of the ploy of brood parasites is ensuring the intruder egg closely resembles the host eggs, especially in color. Otherwise, the host mother may spot the intruder egg and pitch it from the nest. Village weavers keep ahead of the game by constantly changing egg colors to keep the parasitic weavers confused.

Village weavers and people: Village weavers may make minor nuisances of themselves by raiding grain crops for the seeds.

Conservation status: These weavers are not threatened, but are numerous, widespread, and adaptable. ∎

BAYA WEAVER (Ploceus philippinus): SPECIES ACCOUNTS

Physical characteristics: Adult body length is 5.9 inches (15 centimeters). Outside the breeding season, the male and female are similarly colored, yellow-brown with dark streaks on the upper body, off-white below. During the breeding season, the male has a yellow crown and breast, the upper body dark brown with yellow streaks, and off-white under parts.

Geographic range: India and Sri Lanka through southwestern China, Singapore, Sumatra, and Java.

Habitat: Baya weavers live in grassland, scrub, secondary forest, farmed areas, usually near fresh or brackish water.

Diet: These weavers eat mainly seeds of guinea grass, Panicum maximum.

Behavior and reproduction: Males change to brighter plumage during the mating season and start building nests to attract females. Nests, one per breeding female, are built in trees, sometimes alongside hornet nests or aggressive, stinging red ants. In these cases, each species lives in peace with one another, and both gain protection from predators specific to each species.

Each nest is shaped more or less like a vase, constricted in the middle and with an entrance at the bottom. It may hang by a long rope from a tree branch or be directly attached to the branch. The baya weavers build their nests out of sectioned blades of guinea grass, the seeds of which are their main food staple.

The male usually assembles several partially built nests that look like domes with hanging straps, then sings and displays on the unfinished nests to attract females. An interested female will inspect one of these nests carefully. If it suits her, she displays approval and mates, after which either the male or female completes the nest. As soon as the female is busy tending the eggs, the male starts singing and displaying for females on another half-built nest, eventually taking in and mating with as many as three females. A female lays three or four eggs and must care for the chicks alone.

Baya weavers and people: Baya weavers have earned reputations as pests by raiding rice fields. Consequently, the birds often end up as food for humans.

Conservation status: Baya weavers are not threatened. ∎

SOUTHERN RED BISHOP (Euplectes orix): SPECIES ACCOUNTS

Physical characteristics: The southern red bishop is also called the grenadier weaver because of the bright colorings of the male in the breeding season. The adult body length is 4 inches (12.5 centimeters). During the breeding season, the neck, tail and wings of the male become brilliant red-orange, while the breast, underside, and the top of the head and face become a lustrous black. Even the beak changes to black. Out of season, the male's coloring reverts to dull shades of brown. The females look similar to out-of-season males and do not change color during the breeding season.

Geographic range: All of Africa south of the Sahara, except part of southwest, and horn of Africa (northeast).

Habitat: Grasslands with tall grass, near water sources.

Diet: Green or ripe seeds of wild grasses and shrubs, young leaves and flowers, and insects.

Behavior and reproduction: The red bishop forages in tall grasses, plucking seeds from grass stalks, often perching on grass stalks to reach the seeds, and on shrub seeds, leaves, flowers and occasional insects.

The red bishop is polygynous, one male mating with several females who settle in nests made by the male. At the start of a breeding season, groups of males will settle in one large area, among treetops, each male building one or more nests, then singing and posing to attract females.

Oddly enough among weavers, the red bishop is not especially vocal. It will screech if alarmed, and uses a small number of other calls, but nothing drawn out and elaborate as in most other weavers.

Red bishops and people: Red bishops can be serious pests, flocks of them descending on grain fields and helping themselves to the seeds.

Conservation status: The red bishop is not considered threatened. ∎

FOR MORE INFORMATION

Books:

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.

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

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.

Periodicals:

Collias, E. C. "Inheritance of Egg-color Polymorphism in the Village Weaver (Ploceus cucullatus)." Auk 110, no. 4 (1993): 983–692.

Keng, Wang Luan. "Nature's Nest Architects at Sungei Buloh." Wetlands 3, no. 1 (1996). Online at http://www.sbwr.org.sg/wetlands/text/96-3-1-1.htm (accessed on July 12, 2004).

Lahti, David C. "Cactus Fruits May Facilitate Village Weaver (Ploceus cucullatus) Breeding in Atypical Habitat on Hispaniola." The Wilson Bulletin 115, no. 4 (2003): 487–489.

Lawes, Michael J., and Steven Kirkman. "Egg Recognition and Interspecific Brood Parasitism Rates in Red Bishops (Aves: Ploceidae)." Animal Behaviour 52, no. 3 (1996): 553–563

Victoria, J. K. "Clutch Characteristics and Egg Discriminative Ability of the African Village Weaverbird, Ploceus cucullatus." Ibis 114 (1972): 367–376.

Williams, J. G., and G. S. Keith. "A Contribution to Our Knowledge of the Parasitic Weaver Anomalospiza imberbis." Bulletin of the British Ornithological Club 82 (1962): 141–142.

Web sites:

Percy FitzPatrick Institute of African Ornithology: Roberts VII Project. http://web.uct.ac.za/depts/fitzpatrick/docs/listlink.html (accessed on July 12, 2004).