Which bird builds the largest nest in the world?

The sociable weaver (Philetairus socius), also commonly known as the common social weaver, common social-weaver, and social weaver, is a species of bird in the Passeridae family endemic to Southern Africa. It is monotypic within the genus Philetairus. It is found in South Africa, Namibia, and Botswana.

Sociable weavers construct permanent nests on trees and other tall objects. These nests are the largest built by any bird, and are large enough to house over a hundred pairs of birds, containing several generations at a time. The nests are highly structured and provide birds with a more advantageous temperature relative to the outside. The central chambers retain heat and are used for night time roosting. The outer rooms are used for daytime shade and maintain temperatures of 7-8 degrees Celsius inside while outside temperatures may range from 16-33 degrees Celsius.