The impact of sex and age on the nature of dominance hierarchies in black-billed magpies. Pica pica, was investigated. Dominance hierarchies were looked for in 11 unisexual groups each with 10 captive magpies, and 32 mixed-sex groups each with five captive magpies. Strongly linear hierarchies were found in all nine unisexual groups of 10 males. Of the two groups of 10 females observed, one was not linear and the other only marginally so. The occurrence of dominance reversals was 25 times greater in female than in male groups. The difference in dominance relationships between the sexes is discussed in relation to differences in the roles that the two sexes play in the breeding biology of magpies. In all 32 groups of five magpies of [...]
