The fibres first collected are securely wound round the branch or leaf from which the nest will hang. The fibres added subsequently are plaited together until a stalk four or five inches long is formed; this is then expanded into a bell-shaped structure. The bell constitutes the roof of the nursery. When the roof is completed a loop is constructed across its base, so that the nest at this stage may be likened to an inverted basket with a handle.
Up to this point the cock and hen do the same kind of work, both fetch strips of grass or of palm leaves and weave these into the structure of the nest. But when once the loop or cross-bar is completed the hen takes up a position on it and makes the cock do all the bringing of material. She henceforth works from the interior of the nest and he from the exterior.
They push the fibres through the walls to one another. Thus the work progresses very rapidly. On one side of the loop the bell is closed up so as to form a chamber in which the eggs are laid, and the other half is prolonged into a neck, which becomes the entrance to the nest. This may be nearly a foot long; six inches is, however, a more usual length.
The entrance to the nursery is thus from below. The way the owners shoot vertically upwards into it, with closed wings, without perceptibly shaking it is really marvellous.
Nest construction obviously gives the little builders great pleasure. They frequently build supernumerary nests, purely from the joy of building. Each time the cock bird approaches the nest with a beakful of material he cries out with delight. Every now and again in the midst of weaving material into the structure of the nest he bursts into song.
Weaver birds usually build in company; ten or a dozen different nests being found in the same tree. As each little craftsman is in a very excited state, fights between neighbouring cocks frequently ensue, but these are never of a serious nature. I was once the witness of an amusing piece of wickedness on the part of a cock baya. The bird in question flew to a branch near the nest belonging to another pair of weaver birds who were absent. After contemplating it for a little he flew to the nest, and having deliberately wrenched away a piece of it with his beak, made off with the stolen property and worked it into his own nest! Four times did he visit his neighbour’s nest and commit larceny; two of the stolen strands he utilised and the remaining ones fell to the ground. I am inclined to think that the thief was actuated by motives of jealousy; for he deliberately dropped some of the stolen material on to the ground and extracted it from the place at which the nest was attached to its branch, thus weakening its attachment. The victim of the outrage on his return did not appear to notice that anything was amiss.