The three purposes of this study were to summarize the important features of the habits and life history of ptarmigan (Lagopus lagopus, L. mutus and L. leucurus), to describe and compare some places in which each species breeds in western North America and to propose some factors which may influence the distribution of the three species. Ptarmigan are herbivores which show little evidence of important specific differences in diet. All known populations of leucurus and many populations of lagopus and mutus are non-migratory, although seasonal vertical movements may occur. However, some northern populations of the latter two species show annual migratory movements presumably based on food scarcity. Male ptarmigan defend areas of ground in the breeding season. Ptarmigan are monogamous and produce only one brood each year. The onset of egg-laying seems to coincide with the initial disappearance of snow from potential nesting sites. In spring each species selects areas in which to breed. Where three species are present on the same mountain, the ranges of lagopus, mutus and leucurus are progressively further above timberline. The segregation seems to be based primarily on features of vegetation form and terrain. Estimates of height and coverage were used to describe vegetation in places used by ptarmigan. L. lagopus established territories and nested where clusters of shrubs from 3-6 feet in height alternated with openings where plants were less than 1 foot tall (or, if taller, very sparse); the vegetation was relatively luxuriant, with a wide variety of species. L. mutus occupied a zone of tundra similar in vegetation structure but with lower shrubs and a greater proportion of herbaceous vegetation. L. leucurus showed a preference for shrubless alpine areas where plants rarely exceeded 1 foot in height, and where ledges, boulder fields and coarse screes provided crevices for shelter. The available evidence suggests that psychologic factors may control habitat selection. It is proposed that each ptarmigan responds to a set of visual cues which is peculiar to that species. As a result, the range boundaries of a particular population may be set by the occurrence of the features of the environment which are important visual cues. Through such habitat selection, each species of ptarmigan may choose automatically the environment to which it is best adapted. / Science, Faculty of / Zoology, Department of / Graduate

Dispersion and productivity of individual ptarmigan <I>Lagopus mutus </I>in North-east Scotland was compared with the food and cover available. Diet was studied by measuring the proportions of foods in faeces. Adults ate mostly shoots of crowberry <I>Empetrum nigrum</I> and heather <I>Calluna vulgaris</I> in late autumn, winter and early spring. In late spring and summer they ate mostly shoots of blaeberry <I>Vaccinium myrtillus</I>, herbs and moss capsules. In spring cocks gradually increased their intake of blaeberry and hens markedly so in April. These rates coincided with the onset of development of the sexes' gonads and breeding behaviour. Chicks ate mostly insects and herbs during their first two weeks, and after six weeks their diet was similar to that of the adults. Territories were on areas of blaeberry heath, springs and exposed rock and not on areas of grass, sedge tall heather and no rock. Mean territory size varied inversely with the number of territories in the total area occupied. 94% of resting birds were within 1m cover, mainly rock, and 81% of foraging birds were within 3m of cover. Chicks pecked faster and walked more slowly when they were close to cover. Ptarmigan foraged mostly in blaeberry heaths and springs with vegetation less than 7cm tall, whereas red grouse <I>Lagopus</I> <I>l. socticus</I>, used heather heaths, mires and grassland with vegetation taller than 7cm.

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