Ceremonial Gatherings of the Magpie Pica Pica: Territory Probing and Acquisition

During a seven year study of magpie social organisation we collected data to examine the idea that 'ceremonial gatherings' were associated with territory acquisition. Gatherings were initiated by high ranking, non-territorial birds, mainly in the three months prior to the breeding season. Most gatherings resulted in initiators being evicted, but in some cases they obtained a territory, either by displacing the owners, or by repeatedly visiting the same area and establishing a territory of their own, usually on territory boundaries where resistance from established birds was least. About 30% of territories were acquired via gatherings. The various ways in which other long-term territorial species acquire territories are discussed.