towns, Cape sparrows build special nests for roosting, lined more poorly than breeding nests but incorporating a greater quantity of insulating material. An unusual social behaviour has been described from Cape sparrows in Johannesburg. Groups of 20–30 birds separate from larger flocks and stand close together on the ground with tails on the ground and heads held high. These groups sometimes move in an unconcerted fashion by hopping slowly. Often birds will fly up and hover above the ground. During these gatherings birds are silent and are never antagonistic. This behaviour's significance is unknown, and it is not reported in any other sparrow species. Feeding The Cape sparrow mostly eats seeds, foraging in trees and on the ground. The larger seeds of cereals, wild grasses, and other small plants are preferred, with wheat and khakiweed (Alternanthera caracasana) being favourites. Buds and soft fruits are also taken, causing considerable damage to agriculture. Insects are eaten, and nestlings seem to be fed exclusively on caterpillars. The Cape sparrow eats the soft shoots of plants, and probes in aloes for nectar, but these are not important sources of food. Breeding Courtship and colonies The Cape sparrow usually breeds in loose colonies of 50–100 birds. 10 to 20 percent of the breeding birds in each population nest away from colonies, for unknown reasons. The Cape sparrow is usually monogamous, but some records of a male and two females nesting and raising young in one nest have been made in Western Cape. It seems pairs are formed in the non-breeding flocks, but it is not known how pairs are formed, or if the pair bond is for life. Once ready to breed, newly mated pairs look for a suitable nesting site, spending mornings searching, and returning to their flock in the afternoon. Once a site has been selected, both birds begin to build their nest. Other pairs seeking a nest site join them, and in this manner a colony forms quickly. The courtship display is poorly recorded. Ornithologist J. Denis Summers-Smith observed a display in which the male hopped beside the female in a tree, drooping its wings and ruffling the chestnut-coloured feathers on its back. Groups of two or more males have been observed chasing a female. In the house sparrow a similar display exists, in which a female who is not ready to copulate is chased by her mate, who is joined by