Alpine Ibex - Life History

Life History

Although the Alpine ibex is a social species, there exists sexual and spatial segregation depending on the season. Four types of groups exist. Adult male groups, groups made of females and their dependent offsping, groups made of young individuals of 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 of both sexes stay apart. The largest aggregations of either sex, occur in late spring and summer, during June and July. Gatherings of males begin to decrease in autumn, during October and November, and are lowest from the rut to early spring, from December to March. The males then leave their separate wintering areas and gather together again.

There is a linear dominance hierarchy among males. In small populations, which are more cohesive, male ibex 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 the size of the horns. Antagonistic behavior in male can come in the form of "direct" or "indirect" aggression. With direct aggression, a male may bump other with its horns, usually the tips of blunt, or place itself front of its opponent, standing on its hind legs and come down at it with the horns. This may signal that it is ready to clash or it may be attempting a real clash. Indirect aggression are mostly made of intimidation displays.

The breeding season starts in December, and typically lasts around six weeks. During this time, male herds break up into smaller groups that travel in search of females. The rut takes place in two phases. In the first phase, the male groups interact with the females who are all in estrous. The higher the male's rank, the closer he can get to a female. Males will perform courtship displays. In the second phase of the rut, a male will separate from this group and follow an individual female. He will display to her and guard her from other males. Before copulation, the female will move her tail and courtship becomes more intensive. The male will then copulate with the female and then join his group and revert back to the first phase. Gestation lasts around 167 days, and results in the birth of one or two kids, with twins making up about 20% of births.

Alpine ibex reach sexual maturity at eighteen months, but females do not reach their maximum body size for five to six years, and males not for nine or eleven years. The horns grow throughout life, growing most rapidly during the second year of life, and thereafter by about 8 centimetres (3.1 in) a year, eventually slowing to half that rate once the animal reaches ten years of age. Alpine ibex have been reported to live for up to nineteen years in the wild