January 28, 2012

Nest Structure

Naturalists consider these birds' nests to be the most astonishing structures built by birds. This species uses plant fibers and tall plant stems to weave themselves extremely solid nests.
First of all, a weaver bird collects the building materials. It will cut long strips from leaves or extract the midrib from a fresh green leaf. There is a reason for its choice of fresh leaves: The veins of dry leaves would be stiff and brittle, too difficult to bend, but fresh ones make the work much easier. The weaver bird begins by tying the leaf fibers around the twig of a tree. With its foot, it holds down one end of the strip against the twig while taking the other end in its beak. To prevent the fibers from falling away, it ties them together with knots. Slowly it forms a circular shape that will become the entrance to the nest. Then it uses its beak to weave the other fibers together. During the weaving process, it must calculate the required tension, because if it's too weak, the nest will collapse. Also it needs to be able to visualize the finished structure, since while building the walls, it must determine where the structure needs to be widened.

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