Birds perhaps the most beautiful creation of God has varied colour shapes and sizes. I think creator of this wanted to keep himself free while creating organisms so he decided to make a separate class o f Avis where he can keep experimenting with colour shapes sizes and of course voices. Not only different birds have different look ,bird of same species look different at different period of time. Males females of same species look entirely different. And not only difference stricking similarity can be seen between birds of different species.
Baya the weaver bird looks very much similar to sparrow. One can easily get confused. Both male and females look similar but at its breeding period male becomes bright yellow and black. Breeding males have a bright yellow crown, dark brown mask, blackish brown bill, upper parts are dark brown streaked with yellow, with a yellow breast and cream buff below. They make beautiful nests . It will not be wrong to say that they are great engineers,they use leaves and other naturally available fine material to build their house. They make their nests near water resource. Male make beautiful nest and female has full freedom to reject if she finds it unsuitable.They live in colonies n numbers of nests can be seen in a single tree. They make their nest on trees having spikes to prevent their young ones from predators.