Belugas are highly social animals; a group of males may number in the hundreds to thousands. Although year round observation of social behavior in the Beluga is limited because of weather, data from radio tracking studies as well as summertime observations indicate that they have home ranges and live in fission-fusion societies that aggregate in the summertime to molt (See habitat) and then separate themselves based on energy needs (see habitat). Belugas do not defend classical territories but rather alternate between summer and winter home ranges, migrating quickly (6km/hr) between them (Lydersen et al, 2001). It is believed that mating occurs during the winter when groups from different summering locations aggregate into larger wintering sites(Brown et. al., 1999).
Mother and Calf
Bonds between male group members are very weak and it is not uncommon for an individual Beluga to leave one group and join another in a few days. The strongest bond is formed between mother and calf, with a secondary bond being formed between siblings through the mother (Krasnova et al, 2006). Belugas have a long gestational period and calves remain with the mother for a long time (See Reproduction and Rearing). These factors lead to communities of cows and their juvenile offspring forming and staying together for long periods of time. Cows will stay with the maternal school their entire life, males remain with the mother until age 5 (just shy of sexual maturity) when they leave to join bachelor groups but return during the breeding season (Krasnova et al, 2006). Belugas return each summer to the same site as their mother, evidence of this can been seen in studies that have examined mitochondrial DNA (which comes only from the mother) and found that samples taken from the same summering site were homogeneous indicating relatedness on the maternal side(Brown et al, 1999).