Well known for their nest-building abilities, weavers (Ploceidae) are small passerine birds with the majority of the family’s 117 species found in sub-Saharan Africa, and smaller numbers making their homes in tropical Asia. While there are some exceptions, weaver species are very sociable and generally breed in colonies. Sparrow Weavers in Africa are known to build large condominium-style nests with between one and three hundred breeding pairs sharing one structure in which each pair has its own chamber with narrow entrances facing downward. Other species, such as the Lesser Masked Weavers, may build their nests as individual structures, but will nevertheless be found in groups, sometimes with more than one nest dangling from a branch.
Closely related to finches, weavers are sometimes referred to as weaver finches and get their name from the manner in which they build their nests. Thought to be the most elaborate nest-building technique of any bird, weavers use locally available materials such as grass, twigs and fibrous leaves, to weave their nests. Some of the species strip fibrous leaves into fine strands to weave a nest together that will withstand all types of weather, but others are not quite so fussy and will build untidy looking nests which are deceptively strong. They tend to build their colonies near water and they are a common sight hanging from willow trees alongside streams and lakes in Africa. Social weavers, found in Namibia, Botswana and South Africa, build some of the largest colonies of nests in trees and on power lines or other structures. These colonies will house several generations of birds at the same time, and in addition to the protection factor of a large group against predators, these large colonial nests offer protection from the extreme temperatures often experienced in Africa.
Primarily seed eaters, some weaver species are considered by farmers to be pests as they damage crops. The Red-billed Quelea falls into this category. With an adult breeding population estimated at 1.5 billion pairs (with some studies suggesting the overall population is 10 billion birds) found only in sub-Saharan Africa, the Red-billed Quelea is the world’s most abundant wild bird species. In colonies of thousands to millions of breeding pairs, these weavers can decimate a farmer’s field in a matter of hours.