Alpine ibex, as other species of the genus Capra (Nievergelt, 1974; Gonzalez, 1982), is a gregarious ungulate, with a clear social and spatial segregation between the sexes (Couturier, 1962; Nievergelt, 1974; Schaller, 1977; Francisci et al., 1985; Gauthier et al., 1992).
Sexual segregation is at its most during summer and is particularly evident in the oldest and most dense populations (Peracino et al., 1989; Gauthier et al., 1992). In new colonies it is common to observe males and females within the same group for many months of the year (Couturier, 1962).

During summer males coming from different winter terrain, aggregate on the same meadows (Gauthier et al., 1992; Bassano et al., 1997).
As observed in other species (Lott & Minta, 1983; Geist, 1974), aggregation in Alpine ibex is thought to be due to the common need to perform a certain activity (feed, rest, etc.) in the same places and timings, and to seasonal climatic factors, rather than to an instinctive behavioural rule (Gauthier et al., 1992).
Alpine ibex males, being gregarious, are not territorial (Aeschbacher, 1978) and have a rich behavioural repertoire regarding dominance and subordination displays (Schaller, 1977).

7.1. Group composition
In Alpine ibex there is a strong sexual segregation: adult males and females use different habitats and segregate for most part of the year (Peracino et al., 1989). Four different kinds of groups can be identified: herds of adult males, groups of young individuals (especially males 2-3 years old), females with kids and yearlings, and mixed groups. Groups of young can be observed especially at the beginning of summer. They are formed by animals born the year before and who have been displaced by mothers going to give birth soon. Groups of females with kids can be observed all year long but are more frequent during summer (Peracino et al., 1989; Gauthier et al., 1992; Toïgo et al., 1995; Mascellani, 1997). The bond between the mother and its kid appears to be looser than in isard, Rupicapra pyrenaica, and in alpine chamois Rupicapra rupicapra (Gauthier et al., 1992).
It is possible to observe solitary old males, sometimes accompanied by younger males.
Mixed groups appears to be a peculiar characteristics of Caprinae, differentiating them from other ungulates where dominant males tend to be solitary and territorial (Schaller, 1977).

The aggregation of adult males and females is limited almost completely to the rut period (December-January) and shortly after that, and is influenced by climatic factors.
Indeed, adult males are influenced in their movements by the presence of snow in January and February, obliging them to select the rockiest and steeper areas - thus with less snow cover - which are maintained for a long time (Peracino et al., 1989; Toïgo et al., 1995). In those areas food resources are available, even if limited for quality and quantity. Males tend to limit the energetic costs of searching food in the snow, selecting areas in which the food results more (Toïgo et al., 1995). This behaviour has been described also for the Pyrenean ibex (Alados e Escos, 1987).

After April-May, the two sexes segregate completely and mostly same-sex herds occur: Adult males herds, young males groups and females with yearlings and kids (Peracino et al., 1989; Gauthier et al., 1991; Pedrotti, 1995; Toïgo et al., 1995).
Sexual segregation may be due to the reproductive strategies of females, which isolate in spring to reach the birthing grounds, or, as suggested for other northern herbivores (for example the moose Alces alces: Geist, 1974; Miquelle et al., 1992), to the differences among the sexes in the nutritional requirements due to the strong sexual dimorphism (Francisci et al., 1985; Toïgo et al., 1995).

Sexual segregation appears influenced also by population density: in recently re-introduced populations, mixed sexes groups are much more common than in established populations (Couturier, 1962).

7.2. Group dimensions
Aggregation varies with the season. For both sexes the highest number of individuals counted within a group is found in late spring-summer (June-July)(Peracino et al., 1989; Gauthier et al., 1991; Pedrotti, 1995). For males, mean values of 26-30 males per group are counted, with extreme values of more than 90 in the late month of June. For females, groups of about 11 individuals are encountered in July, while in the mixed groups of females and kids, the mean number of individuals tends to diminish (about 9 individuals per group) (Peracino et al., 1989).

Aggregation in males decreases in autumn (October-November) and reaches the lowest values during the rut (December-January), staying like this until March (Peracino et al., 1989; Gauthier et al., 1991; Pedrotti, 1995).

The reasons for aggregation appear to be different for the two sexes. The grouping of females and kids is probably mostly a anti-predator strategy (Toïgo et al., 1995). The advantages of such a strategy are similar to those described for other herbivores and for the Pyrenean ibex: decrease of the individual time spent in vigilance, predator distraction, more collective vigilance, more time for feeding, prey dilution, more defence of the kids, often kept at the centre of the group (Alados, 1988; Quenette, 1990).

For males, it has been hypothesised that the aggregation pattern is related with the distribution and the availability of feeding resources and therefore, it is the expression of a competitive interaction among subjects (Toïgo et al., 1995), as well as with the characteristics of the frequented habitat (Francisci et al., 1985).
When the resources are limited and dispersed, as it happens in spring, in the presence of residual snow, or at high altitudes, in rocky environments, the continuos movements needed to reach them would make impossible the formation of large groups (Alados, 1985b, 1987).

The dimension of the groups of Alpine ibex has been recently correlated with the population size and therefore, group dimension has been hypothesised to be a valid biological indicator of density (Toïgo et al., 1996). A positive cohort effect on body growth has been shown for male ibex (Toïgo et al., 1999a).

7.3. Behavioural repertoire
Schaller (1977) showed that the Caprinae have a complex behavioural repertoire, different from the other ungulates.
The genus Capra has some peculiar behavioural characteristics (Gauthier et al., 1991): i. a high frequency of direct ritualised agonistic interactions, during the whole year; ii. The lack of assaults and chases between males, as well fights among more than two individuals; iii. mounting postures between individuals of the same sex; iv. A sexual repertoire different from the agonistic one.

The ethogram of Alpine ibex has been described in dettail by different authors, especially regarding the reproductive behaviour patterns (Hainard, 1953; Aeschbacher, 1978; Mongazon e Gauthier, 1994). The behavioural repertoire modifies with age and this permits a distinction between different age classes (Gauthier et al., 1991). Old males use an elaborated and ritualised repertoire, while the young males engage in more "primitive" and direct forms of agonistic interactions (Schaller, 1977).
Recent investigations have quantified the vigilance behaviour of lactating females, showing a persistence of a clear anti-predator behaviour also in absence of a real predatory threat (Toïgo, 1999b).

7.4. Reproductive behaviour
In Alpine ibex the rut season starts at the beginning of winter, in the second half of December. There exist, however, geographical differences also depending to the meteorological conditions, in analogy with what described for other species of the genus Capra (Schaller, 1980).

The first signs of the beginning of the rut season are represented by sensible modifications of the composition of male herds, which slowly move towards the areas occupied by females (Peracino et al., 1989).
Three phases are described during the rut of Alpine ibex, according to the social behaviour shown by the males and to the kind of social aggreagation (Aeschbacher, 1978; Gauthier et al., 1991):
- the pre-heat phase, characterised by the presence of many males which show only few courtship behavioural patterns and move solitary on sensible distance, in function of the presence of snow;
- the collective heat phase, characterised by fights among males and a great amount of interactions between males and females. All this still happens within relatively large groups. The fights involve mostly the adult and old males and are characterised by horn clashes and pushes. The fights are probably necessary to define a dominance within the groups and thus to determine the choice of females and the priority during the mating. These fights are generally bloodless, and only very rarely the looser suffers serious wounding;
- The third phase is the individual heat phase, which happens between the end of December and the beginning of January. It is characterised by a progressive reduction of the fights among males and by smaller becoming groups. In this phase it is possible to observe adult males courting isolated females, sometimes accompanied only by their kid. The fecund mating happen in this phase.
Adult and young males use two different reproductive strategies (Apollonio et al., 1996; Apollonio, 1997; Apollonio et al., 1997): The first, being large, use mostly static courtship behaviours, while young males use mostly dynamic courtship strategies, possibly ending in running mounts.