The relationships between group size, activity patterns, and time of day were studied during a mild winter in a protected population of Isard or Pyrenean chamois (Rupicapra pyrenaica pyrenaica) in open montane pastures in the bottom of a central valley, bordered by a beech forest. The size and the total number of groups increased progressively from dawn to the middle of the afternoon. Nearly half of the animals foraged early in the morning, while about two out of five were moving. As the day proceeded, the allocation of time for foraging increased regularly until approximately 3/4 of the animals were observed foraging at about 17:00. Foraging increased initially at the expense of moving, and later to both moving and standing. Then, just before dusk, both group size and time devoted to foraging decreased, as individuals returned to the beech forest to rest during the night in a sheltered habitat. The relative influence of weather conditions and of the digestive physiology of Pyrenean chamois on this spatio...