Monday, November 25, 2013

Family Matters: Elephant Social Structure


By Sophie Wasserman

         A few weeks ago, a friend of mine sent me an article called “This Baby Elephant Being Reunited With Its Dad is the Cutest Thing You’ll See All Day.” And while the video it describes is adorable (what baby elephant isn’t?), and does depict a family reunion, there’s no dad anywhere in the picture. Thus, since Think Elephants is all in favor of education, and this article makes a perfect teaching moment, this week's blog is dedicated to elephant social structure. 
The most basic level of elephant social structure is called the family group. The matriarch (typically the oldest and largest female) is the central figure of the family group, and the rest of members represent generations of her female offspring.  Typically 10-20 individuals make up a family group, and the members spend 70-90% of their time in close proximity to the rest of the group. While females stay with their mother's group for life, a juvenile male elephant will stay with his natal family group until around 10-15 years of age, at which time he will begin to hang out further and further away, until he eventually leaves the family altogether. Once on his own, he may remain solitary, or join up with other males in a loosely bonded bachelor herd. It may seem harsh, but it makes sense evolutionarily; his goal in life is to mate and produce healthy offspring, not an easy task when the only females around you are your mother, grandmother, sisters and aunts.

Family group of African savanna elephants in Amboseli
via Wikimedia Commons
A male will only interact with herds of females when he is looking to procreate, so fathers never have a hand in raising their young offspring. However, female elephants are also never “single mothers.” Females frequently exhibit allomothering behavior, or, in other words, babysitting. Adolescent females, those not quite ready to have their own babies, are often involved in caring for and watching over their younger sisters and cousins.  The mother gains extra comfort, assistance and protection for her calf, and the adolescents learn how to be better mothers to their own future progeny.
Since females stay with their maternal herd, family groups can often grow too large to be supported by the land they inhabit, necessitating a split into two new family groups. These new groups will still spend 35-70% of their time in close association with each other, and thus make up the second tier of elephant social structure, called kinship groups. As populations grow, the final level of organization, “clans,” start to form. Clans on the savannah can consist of anywhere from 50-250 individuals, and are formally defined as kinship groups that share the same geographic range.

Clans can consist of anywhere from 50-250 elephants
via Wikimedia Commons
Important note: All of the above information, as well as much of our assumptions about Asian elephant social structure, is based on research done with African savanna elephants (we’ll talk about forest elephants a bit later). Asian and African elephants inhabit significantly different environments, which has important ramifications not only for differences in how the species lives, but also how we study their behavior. In Africa, most of the work done has been longitudinal observational studies. The open savannas allow for more clear and consistent viewing opportunities, so researchers can park their vehicle a safe distance away and simply observe interactions for hours on end.
Asian elephants, on the other hand, are typically found in more densely packed scrub forests, at time restricting visibility to a few meters away and limiting the opportunities of observational work to the infrequent times when the elephants are encountered in scattered clearings or watering holes.

Asian elephant male on the move, low visibility
via Wikimedia Commons
Some work has been done to try and identify any potential differences in the social organization of Asian elephants. One study in Sri Lanka used behavioral observations, radio collars, and  “molecular scatology,” or the collection of DNA from elephant dung, to establish and study genetic links between closely associated Asian elephants. While the results did suggest that, similar to African elephants, all of the elephants in a family group were of the same matrilineal line (i.e. related through their mothers), the family groups did not seem to organize themselves into larger kinship groups or clans. Additionally, family groups were not as closely associated, only spending on average 30% of their time together.
Once again, one possible explanation for the difference in social structure between Asian and African savanna elephants is differences in their habitats. Mammals in open environments like a savanna tend to cluster in larger groups, while mammals in forested habitats tend to form smaller groups, because of the costs of group living like competition for resources. Support from this claim could be found in further study of the smaller species of African forest elephants, who live in the more densely packed jungle regions of Africa; do they exhibit the same social structure as their savanna relatives, or do they show the less complex organization of Asian elephants since their habitats are very similar? The more we learn about these three species, the more we can understand the environmental factors driving their evolution, as well as the more we can educate the public and protect their currently tenuous existence.

African forest elephant
via Wikimedia Commons

So now that you know about elephant society, can you tell who's really involved in the video below? (Hint: no dads were involved in the making of this adorable clip, but there was still a close-knit family of fearsome females to show this baby some love)


References:

Fernando, P., & Lande, R. (2000). Molecular genetic and behavioral analysis of social organization in the Asian elephant (Elephas maximus). Behavioral Ecology and Sociobiology48(1), 84-91.

Thornton, M. (2013, October 14). [Web log message]. Retrieved from http://www.buzzfeed.com/maycie/elephant-family-reunion-hugs-video-addo-park

Media:

Asian elephant panning by Kalyan Varma via Wikimedia Commons

Elephant herd by USAID Africa Bureau via Wikimedia Commons

Herd of elephants by Ben Lieu Song via Wikimedia Commons

Loxodonta cyclotis by Thomas Breuer via Wikimedia Commons


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