Gender effects on aggression, dominance rank, and affiliative behaviors ina flock of captive adult cockatiels (Nymphicus hollandicus)

Agonistic and affiliative behaviors and spatial positioning were studied in a small psittacine species, Nymphicus hollandicus. Subjects studied were f lock-housed breeders including five hens and seven cocks. Fifteen-minute fo cal animal samples were collected for the entire Book in a randomly distrib uted order juring mate selection and the onset of the breeding season. All agonistic behaviors were recorded, including the winner and loser of each i nteraction, along with allopreening and copulation behavior. Point samples were recorded every 60 s to determine social spacing. Rates of aggression w ere significantly higher for male cockatiels than female cockatiels. Result s based on dyadic agonistic interactions showed males to rank significantly higher in the social hierarchy than females. Associations within the Rock were not random. Individual birds associated more with specific birds than would be predicted by chance. Analysis of spatial data revealed that there were both same-sex and opposite-sex preferred associations within the flock . Male cockatiels engaged in allopreening behavior with females significant ly more than with other males. Observations of breeding and nesting behavio rs revealed pairs, a triad, and extra-pair mating. (C) 2001 Elsevier Scienc e B.V. All rights reserved.