There are two species of weaver birds recorded in Sri Lanka. The Streaked weaver (Ploceus manyar) is confined to coastal areas, where as the Baya weaver (Ploceus philippinus) is a rather common sight around paddy fields all throughout the country, except the central mountains. You can easily define their presence by seeing their unusual nest. Baya weavers are social birds and most of the time they can be seen as a flock on paddy fields, reed beds and edges of water ways etc. Breeding season of Baya weavers is defined by monsoon and availability of food. Often they are seen making their nests on top of tall, thorny trees including coconut trees to avoid predators and nesting in colonies. There are 15 to 20 birds in the colony on a tall tree in the middle of the Kaduruketha paddy fields.
Baya weavers are well known for their nest building and it is solely done by male birds. Their nest building is an interesting behaviour to watch. The nests are woven with paddy leaves, long strips torn from coconut fronds and long grass. The nest has two chambers including main nesting chamber and entrance chamber with long vertical tube. A male bird will do approximately 500 trips to complete the nest and it will take 18 to 20 days.
Once nest is partially complete – without vertical tube – after about 8 days, the male bird will begin to show his nest to passing females by flapping his wings and calling while hanging from the nest. Female birds come and inspect the nest and will signal her acceptance (If female refuses, male has to build another one until he get acceptance). Once they have paired, the male bird will complete the nest by building a vertical entrance tube. The female may do final touches of the nest by decorating the interior with mud blobs. The female lays about 2-4 eggs and will incubate for about 15 -17 days. Chicks leave the nest after about two weeks.
The male bird has to build many partially built nests until he wins his partner. You can see these partially build nests at any Baya weaver colony and it can be a failed attempt by the male bird or ongoing mission to win his partner.