Social Organization of Willow Ptarmigan on Their Breeding Grounds in Interior Alaska

Moss, Robert

An exploratory study was made of social organization in a migratory population of Willow Ptarmigan on their breeding grounds. A creek bed supporting a good growth of Salix alaxensis and Salix pulchra was occupied by territorial cocks before the adjacent hillside, where there was no S. alaxensis and less S. pulchra than in the creek bed. S. alaxensis was the preferred food, but was completely exhausted by early May when the birds turned more to S. pulchra. The droppings of birds feeding on the hill contained less urates than those of birds feeding in the creek and it was inferred that their diet was poorer. Birds from the hillside trespassed into the creek in order to feed and were ejected when discovered by the territory owners. From this and other circumstantial evidence, it was inferred that the hill cocks were less dominant than the creek birds and had been forced into the poorer hillside habitat by territorial competition. This habitat had not been occupied in 1969, when numbers in the area as a whole were inferred to have been lower. A few nonterritorial cocks and possibly one unmated hen were present. These birds probably did not breed. Rock and Willow Ptarmigan occupied territories on the same ground. On the few occasions when cocks of the two species interacted, the Willow Ptarmigan were dominant. Cocks of both species attempted to court hens of the other species, who usually flew off.

Social Organization of Willow Ptarmigan on Their Breeding Grounds in Interior Alaska

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