the chestnut sparrow was an obligate nest parasite (not a brood parasite, like many Old World cuckoos and cowbirds). Payne also noted in his paper that "Nest parasitism is generally thought to have been a stage in the evolutionary development of brood parasitism", an idea that remains accepted, and suggested the chestnut sparrow could be evolving towards obligate brood parasitism. However, it is known that besides parasitising the nests of weavers or using their abandoned nests, the chestnut sparrow also builds its own nests. Nests built by the chestnut sparrow, like most sparrow nests, are untidy domed structures which are made of grass and lined with feathers. Its breeding season varies between different regions, following rains, and the breeding seasons of its hosts in areas where it parasitises nests; as a result it has been recorded breeding in every month of the year across its range. At Payne's study locality the breeding season of the chestnut sparrow lagged behind that of its host. The sparrows began courting when the weavers started constructing their elaborate nests. Once the breeding season began, "the first impression was of the sparrows nesting and the grey-capped social weavers unobtrusively skulking nearby". Males displayed around the new weaver nests, crouching, raising and quivering their wings in a shallow V, and giving a high, twittering trill. The males were chased by the social-weavers, but returned persistently, until joined by females. When a female came near a displaying male, the male would increase his rate of wing quivering, spread and depress his tail, and bow down his head, until his body formed an arc. This exaggerated display may be an adaptation related to pair formation in the absence of male nest-building, and it may also serve to focus attention in breeding colonies and keep the birds in a colony together, as colonies are in clumps of trees surrounded by similar habitat. During Payne's study, copulation was seen only in the acacias, around the social-weaver nests. Females would fly to displaying males and solicit copulation in typical sparrow fashion, crouching, quivering, and drooping their wings. When males saw displaying females, they would fly to them and mount them immediately. Males continued their wing quivering during copulation, and females would crouch, quiver, raise their head, and hold their tails horizontally. After a copulation the female would fly off and the male would continue displaying. During this courtship and afterwards, males