Elephant Social Organisation
Asian elephants were thought to have a similar social organisation to African savannah elephants, with a very hierarchical complex social structure. However, our research suggests that Asian elephants have a very different social organisation.
In both African elephants (Loxodonta africana and Loxodonta cyclotis) and Asian elephants (Elephas maximus), females and young ones live together as a herd or group. Males as they come into adulthood around 10-15 years of age, tend to drift away from the group. As adults males are mostly solitary. In Sri Lanka most villagers have a special name for such elephants – ‘thani-aliya’ or lone-elephant. It used to be believed that the older females in a group chase away the males when they come into adulthood. However this is not true and males leave the herd of their own accord. Even as adults, males will continue to interact with the herd that they were born into. However they do not ‘hang out’ with a single female group all the time. Instead they will mingle with any female group they meet with and ‘check out the ladies’.
The basic element of an elephant herd is the mother-calf unit, which is a female with the baby that she is nursing, hence dependent on her. A female will nurse a baby for about two years, after which it starts to be more independent of the mother. As the male babies grow up into adults they leave, but the female babies grow up into juveniles and adults staying with their mother. This then forms the first level of social organization in elephants. It is usually called the ‘family group’, which consists of a female, and her female offspring of all ages and younger male offspring. At about 8-10 years of age the females come into their first estrus period or breeding condition. Elephants have a gestation period of 22 months. So a young female will give birth to her first baby at about 10-12 years of age. She will have the same relationship with her babies as her mother did. Thus after many years, the family group may expand to include three to four generations of elephants. The females will reproduce till about 35-40 years of age and thereafter will be post reproductive but will still remain with the group. Elephants in the wild probably live to about 40-50 years of age and not beyond, although they can live up to about 70 years in captivity.
It is not very clear why female elephants and young live in herds. In some places there may be an advantage to group living such as protection from large predators who could take a baby, such as lions in Africa or tigers in India. There may also be some advantages in having other females around for taking care of babies and juveniles, as in preventing them from wandering away and getting lost. However, it is not clear what the actual benefits are, to a female and juveniles in having aunts and cousins living as a group. Even though the benefits are not clear cut, group-living has distinct disadvantages. Living together in a herd, you have to share food with everyone. So the entire group has to walk around till enough food for the whole group is found. Therefore habitat conditions probably have a major influence on group size. In dry scrubby habitats such as the Yala National Park, food is not that plentiful unlike in luxurious grasslands. Therefore the group size maybe limited much more.
A female may give birth to a baby every 4-5 years and with the female babies growing up into adults and also reproducing, soon the ‘family group’ grows in size. Either when the oldest female who is the grandmother or great grandmother of them all dies, or because the family group now becomes too big given the habitat conditions, it will split into a number of new ‘family groups’ with an adult female as its focus. When that happens, the related family groups are thought to continue to spend more time with each other than with unrelated groups, leading to a second level of social association called a ‘kinship group’ or a ‘bond group’. Similarly with many decades of this process, each family group in a kinship group will split and evolve into a kinship group of its own, and then the entire collection of kinship groups will be termed a ‘clan’. The kinship groups within a clan will continue to associate with other related kinship groups but of course to a lesser extent than between the family groups that forms each kinship group. Female groups in African elephants are thought to have a social organization with about 3-4 levels of relatedness based such association (Lee 1991; Moss 1988; Wittemeyer et al. 2009). However even among African elephants, social organization, its complexity and relatedness patterns on which it is based on may differ between populations (Thouless 1996; Wittemeyer et al. 2009).
Social organization in Asian elephants may not be as hierarchical and complex as in African elephants but more fluid with less strong bonds between individuals (Fernando & Lande 2000; Vidya & Sukumar 2005; de Silva et al. 2011; de Silva & Wittemeyer 2012). Especially in Yala, we do not see a highly complex and hierarchical social organization amongst females. The basic mother-calf unit of course is very clearly there. However, the ‘family group’ the first level of social organization appears to be much more fluid and less tightly knit. Some female offspring also become independent as they become adult. Most females and mother-calf units associate in small groups with the members of such groups changing regularly. Whether higher levels of social organization such as ‘kinship groups’ and ‘clans’ exist is not very clear.
In African elephants, the oldest female in a group who is the progenitor of all the group members is also thought to play a very important role in leading the group. She is termed the ‘matriarch’ and is thought to decide what the group does, where it goes and when it does things. In Sri Lanka, even when there is a ‘matriarch’ present in a given group, she does not seem to play a major leadership role. In instances of perceived threat it is often a younger female that seems to take the initiative to confront an aggressor. Where the group moves from one area to another, often the oldest member of the group follows the others.
Therefore, while elephants in Sri Lanka also have a complex social organization built around females, it maybe looser and less hierarchical than that of African savannah elephants. While African savannah elephants have been studied closely for many decades, the social lives of Asian elephants are largely unknown. This is partly because of the difficulties of studying Asian elephants, which live in habitats with poor visibility. Another reason that makes studying Asian elephants very difficult is the ubiquity of human-elephant conflict in Asia. As a result, Asian elephants have behaviourally adapted to avoid humans by becoming largely nocturnal and moving inside cover the moment they realize there are people around. Yala is one of the few places in the world where Asian elephants can be observed very closely throughout the year. That is because some of the female herds in Yala are very habituated to people, giving us an unparalleled window to the intimate moments of their lives.
Our research is based on identifying individual animals and building up photo catalogues. Currently, we have catalogued over 200 males and females in Yala National Park, where we are looking at both male and female social organisation (see Yala Elephant Groups).
Yala provides a unique opportunity to study details of Asian elephant social organisation because of the extensive road network and the presence of habituated groups. Consequently, one can observe elephants at very close quarters for long periods of time without disturbing them, while they go about their daily routine.
Fernando P & Lande R (2000) Molecular genetic and behavioural analysis of social organization in the Asian elephant (Elephas maximus). Behavioral Ecology and Sociobiology 48:84-91.
Lee P (1991) Social life. In: Eltringham SK (ed) The Illustrated Encyclopedia of Elephants. Salamander, London. pp 48-63.
Moss CJ (1988) Elephant Memories: Thirteen Years in the Life of an Elephant Family. William Morrow, New York.
de Silva S & Wittemyer G (2012) A comparison of social organization in Asian elephants and African savannah elephants. International Journal of Primatology.
de Silva S, Ranjeewa ADG & Kryazhimskiy S (2011) The dynamics of social networks among female Asian elephants. BMC Ecology 11: 17.
Thouless CR (1996) Home ranges and social organization of female elephants in northern Kenya. African Journal of Ecology 34: 284–297.
Vidya TNC & Sukumar R (2005) Social organization of the Asian elephant (Elephas maximus) in southern India inferred from microsatellite DNA. Journal of Ethology 23: 205-210
Wittemyer G, Okello JBA, Rasmussen HB, Arctander P, Nyakaana S, Douglas-Hamilton I & Siegismund HR (2009) Where sociality and relatedness diverge: the genetic basis for hierarchical social organization in African elephants. Proc Biol Sci. 276: 3513-3521.