Cooperation and conflict in the building and maintenance of the compound nests of monk parakeets Myiopsitta monachus

Colonial birds often breed at high density, generating conflict among neighbours over the use of nest-building materials. However, in a few colonial species, breeders appear to cooperate in the construction of compound nests that contain multiple breeding chambers within a single nest structure. The relative contributions of individual birds and the balance between cooperation and conflict among close neighbours in such species have rarely been examined. In this study, we investigated evidence for cooperation and conflict in the building and maintenance of the nests of monk parakeets Myiopsitta monachus in an invasive population in which compound nests are frequent. First, we found that males invested more in nest construction than females and when more than one male occupied the same breeding chamber multiple males contributed to the same nest. Females, by contrast, invested more in nest defence than males. Second, we found that there was conflict among pairs over nest material, with kleptoparasitism of nesting material and defence against conspecifics evident. We conclude that nest-building in monk parakeets involves both cooperation and conflict. Breeders often tolerate the budding of nests, which are often built by relatives, but that pairs are also in conflict over the use of nest material.