Seasonal changes in aggressive behavior of female spruce grouse

Abstract

The behavior of female Franklin's grouse (Canachites canadensis franklinii) in response to a playback of female aggressive calls was recorded in southwestern Alberta during the spring of 1974 and late winter, spring, summer, and autumn of 1975. Resident adults initially responded with aggressive calling during late winter and continued to call in response to the recording throughout spring. Only those overwintered yearlings that were establishing spring territories within their winter ranges responded by calling in early May. The onset of aggressive calling by resident yearlings coincided with the spring dispersal of those yearlings that were either not responding overtly or were fleeing from the site from which the sound was emanating. Dispersing yearlings only called aggressively after spring dispersal when they had established territories. The highest level of aggressive calling occurred when females were evenly spaced on territories and included the periods of mating and laying. Aggressive behavior thus appears to be a manifestation of female territoriality with a resulting uniform spacing during spring. It also appears to be a mechanism for adjusting the density of females in a local breeding population.