A case of bigyny in the Hawk Owl Surnia ulula: spacing of nests and allocation of male feeding effort

Abstract

Apparently the first known case of bigyny in the Hawk Owl was observed in the northboreal zone of SE Norway in 1984 . The distance between the primary and secondary nest was 1050 m, and the two females defended separate territories within the single territory of the male . The secondary female started egg laying approximately 26 days later, and laid one egg less than the primary one. The male fed his two females at the same rate until the primary clutch hatched. During the next two weeks the prey consumption rate of the primary nest was lower than the prey capture rate of the male, and the surplus was fedto thesecondary female . When this surplus decreased, the secondary female abandoned her clutch . However, she stayed in her territory and begged for food for another two weeks, but did not receive any, and did not renest. The primary brood was successfully raised to fledging .