Age Determination and Dating Nesting Events in the Willow Ptarmigan

Abstract

A thorough knowledge of sex and age ratios and the nesting phenology of game birds has become an integral part of modern game bird studies. The consistent and regular moult of the primaries in game birds has proved valuable in facilitating the assembling of comprehensive data on nesting events when the moult pattern is understood. This regular wing moult pattern was first described and used as an accurate aging method by Bureau (1911) for the common partridge, Perdix perdix, and the red-legged partridge, Alectoris rufa (1913). In later studies, the wing moult and its use in age determination and dating of nesting events have been described for the bobwhite quail, Colinus virginianus (Petrides and Nestler, 1943; Thompson and Kabat, 1950; Petrides, 1952; and Reeves, 1952); the pheasant, Phasianus colchicus (Buss, 1946; Kabat, Thompson and Kozlick, 1950); the ruffed grouse, Bonasa umbellus (Bump et al., 1947; Hale and Wendt, 1951). McCabe and Hawkins (1946) added further data on the wing moult of the partridge; Thompson and Taber (1948) were the first to use wing moult data for producing reference tables for dating nesting events in pheasants, partridges and bobwhite quail. A similar reference chart for dating nesting events in the willow ptarmigan, Lagopus lagopus, is presented here as an aid in assembling nesting data. Whereas much material on the nesting of the willow ptarmig n is available in the Norwegian literature, very little is known and recorded about t breeding of this bird in Canada and Alaska.