One of the main duties of the family within the herd relates to birth and childcare. The sisters of the mother are key role players, supporting her during the birth, as well as during the years that follow. It is at this time that the calf requires training that prepares them for adulthood, including how to search for food and water, how to look for a mate (in the case of male calves), and how to fulfil their specific role within the herd.
Of course, individuals continue to "come and go" from the core herd over the course of many years. Some researchers do not consider these herds to be families, and there is little clear definition as to when the herd can no longer be considered a family according to the number of family members as opposed to "friends" or acquaintances.
An interesting unity forms among new elephants when the herd splits (due to excess numbers and/or shortages of food or water). These are known as bond groups. Usually, members of bond groups are related in some way, but they can comprise of up to 4 or 5 different families. Members of the bond group are not as committed to one another as family members are, but they are still fiercely loyal and will defend one another and assist with the childcare of the other cows calves. The cohesiveness of these groups is dependent on the personalities of the individual members and how closely related they are. Most importantly, the strength of the matriarch's leadership will influence the nature of the relationships among members of the bond group.
The quality of the relationships enjoyed within the herd plays a vital role in the cohesive loyalty of the herd as a whole. This depends much on the family structure. A good matriarch appreciates this and works hard in establishing strong bonds.