spring. Female home ranges are usually smaller than those of males. Alpine ibex appear to have a low rate of predation and in Gran Paradiso typically die of age, starvation, or disease. Foraging Alpine ibex are strictly herbivorous, with over half of their diet consisting of grasses, and the remainder being a mixture of mosses, flowers, leaves, and twigs. If leaves and shoots are out of reach, they often stand on their rear legs to reach this food. Grass genera that are the most commonly eaten are Agrostis, Avena, Calamagrostis, Festuca, Phleum, Poa, Sesleria, and Trisetum. The climbing ability of the Alpine ibex is such that it has been observed standing on the sheer face of the Cingino Dam in Piedmont, Italy, where it licks the stonework to obtain mineral salts. Life history Although the Alpine ibex is a social species, they segregate sexually and spatially depending on the season. Four types of groups exist: Adult male groups, female-offspring groups, groups of young individuals 2–3 years old, and mixed-sex groups. Young groups are numerous at the beginning of summer, but are expelled by females at the end of their gestation period. Female and offspring groups occur year-round, at least in an area of the French Alps. Mixed-sex groups of adult males and females occur during breeding, which lasts from December to January. By April and May, the adults separate. The largest aggregations of either sex occur during June and July. Gatherings of males begin to decrease during October and November, and are lowest from the rut from December to March. The males then leave their separate wintering areas and gather again. A linear dominance hierarchy exists among males. In small populations, which are more cohesive, males know their place in the hierarchy based on memories of past encounters, while in mobile and large groups, where encounters with strangers are common, rank is based on horn size. Antagonistic behavior in males can come in the form of "direct" or "indirect" aggression. With direct aggression, one male bumps another with his horns or places himself in front of his opponent. He stands on his hind legs and comes down on his opponent with his horns. This may signal that he is ready to clash or may be attempting a real clash. Indirect aggression is mostly intimidation displays. Reproduction and growth The breeding season starts in December, and typically lasts around six weeks.