Birds as Architects


Whatever problems our feathered friends may have, a housing shortage is not one of them. Birds are experts at designing and building their own homes, and the building materials they use are plentiful. It is interesting to know that the ancestors of the birds that build nests in your garden worked to the same plan and used the same kind of materials thousands of years ago.

As a general rule, birds nest near the places where they find their food. Naturally they make use of the available building materials. Field birds use grasses and wool and horsehair they find clinging to bushes and fences. Birds of the woods make use of twigs and roots, and those that live near water often use sedges and reeds.

It seems that the smaller the bird, the better the nest is constructed. The tiny wren, for example, is a first-class architect. The nest of the eagle, however, is poorly put together.

One of the most clever nest builders among European birds is the long-tailed tit (No. 1). This bird will use over two thousand feathers for lining its comfortable nest, which is beautifully built of moss, fur, and lichen. Woven into the building materials is a large amount of spiders’ web, which makes the walls of the nest elastic. The elasticity of the nest allows it to expand as the family grows larger.

Another remarkable nest is made by the mallee hen of Australia (No. 2). Unlike most birds, the mallee hen doesn’t sit on her eggs in order to hatch them. She builds a nest that keeps them warm for her! First she scratches a hole in the ground. Then she lines it with sand and leaves. Next she builds a mound of sand on top of the sand and leaves. Into this mound she carefully places her ten or more eggs, arranged in layers. The heat of the sun and the heat produced by the rotting leaves underneath the mound of sand keep the eggs warm until they hatch. The brilliantly colored bowerbird (No. 3) builds not only a nest, but also an elaborately decorated framework of twigs and plant stems close beside it. This framework is decorated with berries, shells, and flowers. The flowers are replaced as they wither. Some of these bowers are up to six feet in length, with a pathway often covered with fragments of bone, shell, and colored stones.

The Indian tailorbird is a great nest builder (No. 4). This bird actually sews two leaves together with threads of vegetable fiber, then lines the pocket-shaped nest with wads of cotton. This makes the nest snug, warm, and waterproof.

The weaverbirds make their hanging nests of woven grass. These nests look as though they had been woven on a loom. They are bottle-shaped and have an entrance hole near the bottom. Weaverbirds nest in colonies in South Africa. Many are found close together under a single tree.

[illustration] Illustrated by Ted Nagata