Aggressive behavior and the dispersion of female blue grouse

Abstract

In the field, nesting hen blue grouse (Dendragapus obscurus fuliginosus, Ridgway) show fidelity to home ranges and these are evenly spaced. Explanation of this is difficult. Hen blue grouse in an aviary were tested for aggressive behavior that might function to space them in the field. Reaction of hens to their mirror image was recorded and this was greatest during the period hens squatted and laid eggs, and decreased through incubation. The difference was statistically significant. Of the five acts which determined the index of activity, three were apparently aggressive, one was apparently investigative, and one was apparently conflict and fear. The results support the idea that dispersion of hens during the breeding season is caused by aggressive behavior.