make up to 500 trips to complete a nest. The birds use their strong beaks to strip and collect the strands, and to weave and knot them while building their nests. The nests are often built hanging over water from palm trees and often suspended from thorny Acacias and in some cases from telephone wires. Although the birds prefer thorny trees, they sometimes use avenue trees in urban areas. Nests are often located on the eastern side of the tree, where they are believed to provide shelter from the Southwest Monsoon; however, late breeders are more likely to build their nests in other orientations relative to the trunk of the nest tree. Abandoned nests are sometimes used by mice (Mus booduga) and other birds such as munias. Nests are built mainly in colonies but isolated nests are not unknown. Nests are often built from thorny Acacia or palm trees ( mainly Phoenix sylvestris) and hang over open water. Young males may build experimental nests among reeds. In Burma, birds often build nests under the eaves of buildings, but this habit is uncommon in India. The males take about 18 days to construct the complete nest with the intermediate "helmet stage" taking about eight days. The nests are partially built before the males begin to display to passing females by flapping their wings and calling while hanging from their nests. The females inspect the nest and signal their acceptance of a male. Once a male and a female are paired, the male goes on to complete the nest by adding the entrance tunnel. Males are almost solely in charge of nest building, though their female partners may join in giving the finishing touches, particularly on the interiors. Females may modify the interiors or add blobs of mud. A study has found that nest location is more important than nest structure for the female when it selects the nest and mate. Females prefer nests high in trees, those over dry land, and those on thin branches. Both males and females are polygamous. Males build many partial nests and begin courting females. The male finishes the nest only after finding a mate. The female lays about two to four white eggs and incubates them for about 14 to 17 days. Males may sometimes assist in feeding the chicks. The chicks leave the nest after about 17 days. After mating with a female the