Aggressive and Spacing Behavior of Female Blue Grouse

Abstract

Female blue grouse (D. obscurus) on Stuart Island, Washington [USA] were found to interact aggressively with female dummies in the prelaying period when a taped cackle call was played. Interactions included tail fanning, wing dragging, everting the white patagium feathers to display a shoulder patch, head bobbing, neck stretching, jump attacking, pecking, and diving attacks. Threatening and aggressive calls included cackling calls with inflections, a Nee-uk call, and attack and scream whinny calls. The frequency of aggressive interactions was greatest in the latter half of April, a period when hens were selecting nesting sites. The prelaying ranges of 12 hens were mostly mutually exclusive and showed a dispersed distribution relative to each other. However, there were interspaces sufficient for other grouse to nest. Aggressive behavior and mutual avoidance of females resulted in a dispersed distribution of nest sites. Such spacing should enhance the reproductive fitness of females by reducing predation rates on hens, eggs, and young.