When you see a sparrow trying to build a nest in a small hole in the ceiling or near the ventilator, you seldom think about the thousands of trips it makes to gather materials required to build its nest. But you would be amazed to know the range of forms, shapes and sizes of nests.
To ensure the safety of their offspring, birds strive hard to make their nests inaccessible and inconspicuous. Careful selection of the building-site is important in ensuring the survival of the chicks.
While some birds like jacanas and grebes make their nests on watery surface, many others burrow into the earth. Weaver birds and tailor birds weave and sew a cup-shaped nest in a tree, and woodpeckers chisel their nests into tree trunks. The only tools available are their beaks and feet.
As architects they need a simple plan to ensure the shape and size of their nests. Birds tend to abandon a pattern that doesnt conform to its pre-determined model.