Social Organization and Territorial Behaviour in a Willow Ptarmigan Population

Abstract

Willow Ptarmigan in Norway showed the same postures and calls as Red Grouse. Territorial behaviour occurred at dusk and dawn from September to December and from April to June. During the day cocks did not defend territories. This daily rythm was apparently acquired rather than genetic, since captive birds did not show it. Whereas Red Grouse at high density display at all times of day, Willow Ptarmigan seldom do so, regardless of density. Cocks showed higher site tenacity than hens. There was no tendency for young cocks to establish territory close to the territory of their parents.