WEAVER  

Weavers are birds of small to medium size, many of which are known for weaving complex nests. More than 150 species, including the well-known house SPARROW, Passer domesticus (also called English sparrow), are found throughout the world; weavers are especially prevalent in the Old World, particularly Africa. These species make up the family Ploceidae, closely related to the WEAVER FINCH family Estrildidae.

Weavers usually have bodies 7.5 to 25 cm (3 to 10 in) long but are variable in total length because some, like the African whydah Coliuspasser progne, have long tails, sometimes 63 cm (25 in) in length. Most have short, conical bills that are good for cracking seeds, their chief food. Weavers are generally sedentary and primarily arboreal, but they do spend much time on the ground in search of food.

In general, weavers build globular nests with side or bottom entrances often extended into tubes or spouts. The nest fabric, usually strong and pliant, is woven by the use of intricate stitching techniques. The nest of the social weaver, Philetairus socius, is particularly elaborate, with vertical tunnels leading to canopied retort-shaped chambers. Many species are colonial; the extreme is reached by the red-billed dioch, Quelea quelea, an African bird that breeds in large colonies with up to 10 million nests. They migrate in locustlike flocks, causing great damage to crops. Some widowbirds do not build nests but lay their eggs in the nests of other birds and trick them into raising the young, which have markings that resemble those of the foster parents' young.