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

Abstract

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 Myiospsitta 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.

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 Myiospsitta 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.

Las aves coloniales suelen criar en comunidades con una alta densidad, lo que genera conflictos entre los vecinos por el uso de materiales para la construcción del nido. Sin embargo, en algunas especies coloniales, los individuos reproductores parecen cooperar en la construcción de nidos compuestos, que contienen múltiples cámaras de cría, pero mantienen una estructura de nido único. La contribución relativa de los individuos y el equilibrio entre la cooperación y el conflicto entre vecinos cercanos son aspectos muy poco estudiados en estas especies. En este estudio, analizamos los indicios de cooperación y conflicto en la construcción y el mantenimiento de los nidos de las cotorras argentinas, Myiopsitta monachus, en una población invasiva en la que los nidos compuestos son frecuentes. En primer lugar, observamos que los machos invirtieron más en la construcción del nido que las hembras y que cuando más de un macho ocupaba la misma cámara de cría, múltiples machos contribuían al mismo nido. En cambio, las hembras invirtieron más en la defensa del nido que los machos. En segundo lugar, constatamos que se generaban conflictos entre parejas por el material de nidificación y que se producían episodios de cleptoparasitismo de material de nidificación y de defensa en contra de ejemplares conespecíficos. Concluimos que la construcción de los nidos de las cotorras argentinas trae consigo cooperación y conflictos. Los reproductores suelen tolerar que se vayan construyendo nidos adosados al ya existente, a menudo por parientes, pero esas parejas también entran en conflicto por el uso del material de nidificación.