Hello, Goodbye: Fission-fusion Dynamics at work

Like many human beings in our modern, interconnected world, I am a wanderer.  I was born in Milwaukee, Wisconsin, U.S.A., where much of my family still lives.  I have lived and worked in California (north and south!), Michigan, Idaho, and Montana.  I have visited Mexico, England, France, and Italy.  Now I call Kenya my second (or third? or fourth? I forget...) home.

As a result of traveling to many different places - with my family, for various jobs, and on school and church trips - I have learned a hard lesson: how to say goodbye.

Goodbyes are never easy.  But we experience them frequently.  As humans today, we often end up loving many people who are scattered across our region (city/county/province/state), our country, or even the globe.  We grow up, and then we move and part ways with our childhood friends.  We graduate from high school or college and have to leave the people we knew there behind.  We change jobs, lose our relationships with the people at one workplace, and have to start building such relationships again somewhere else.  We have to learn to conduct ourselves in a wide variety of social situations, adjusting to the fluid circumstances and changing memberships of an astonishing number of different types of social groups, moving between groups as life leads us in new directions, saying hello to new friends and then almost as quickly saying goodbye.

We think of this bittersweet reality as a uniquely human experience.  Yet there are other animals who live in complex societies like ours, meeting and interacting with many different individuals over the course of their lifetimes and having to watch them come and go.  Such societies are known as "fission-fusion" societies.  In fission-fusion societies, the size and composition of a social group can change rapidly, as individuals come together (fuse) or split up (fission) to adapt to varying circumstances.  Examples of species that exhibit this dynamic social structure include chimpanzees, bottlenose dolphins, African elephants, and... spotted hyenas!

Although a clan of spotted hyenas can number, on average, between 20 and 60 individuals, all of those individuals don't get to see each other all of the time.  The clan will typically split into smaller subgroups to hunt, rest, or travel, but come together again to defend a common resource such as the communal den.

Within our "Talek West" clan in the Mara, we have recently been watching fissioning, or splitting, happening, as the entire clan has started to separate into three distinct subgroups: the "Main DOC" group who frequent "Main Den One Creek", the "Pond" group who hail from Pond Lugga, and the "KCM" group, or "Kinda C M" group, so named because we can only "kinda" see them at their den.  Each of these groups has its own separate communal den, and for the most part we have been seeing the hyenas associating only within their particular group.  Furthermore, we have seen the groups aggressing intensely on each other over resources such as food, to the point of one group banding together to chase another off a resource.  All of the data hasn't been analyzed yet, but there is a high possibility that these three subgroups are fissioning into three separate clans - or already have!

However, we have also seen hyenas from the different subgroups walk past each other and ignore each other completely, and we have also seen (rarely) a few exceptional hyenas involving themselves with more than one group.  So it is still unclear whether this is a true, permanent fission into separate clans or not.  In any case, there is clearly some kind of division happening within the clan.

In some cases, this fissioning has split up entire families.  For example, Twister is in the Main Doc group, but Twister's sister, Parcheesi, and mother, Adonis, live with the KCM group, and Twister's niece, Bonnet, lives in the Pond group.  Although these four hyenas are related, we do not see them interacting now that they are in different subgroups.

Adonis, an adult female hyena.  Her family is now scattered across three different subgroups of the Talek West clan.

Why the split?  It is hard to tell at this stage.  Studies have shown that animals can reach both an ecological or environmental "carrying capacity" (the environment can only provide enough resources for a certain number of individuals at a time) and an upper limit to their affiliative, or bonding, abilities (each individual animal can only maintain a certain number of affiliative bonds or "friendships" with other individuals at a time).  A variety of social and ecological factors can work together to make a group of animals change membership, grow or divide.  Some examples of such factors are described in the references I list below this post.

As for me, my current physical "fission" from my family, required by my being in another country, is not a permanent social split by any means!  But as I have split from them temporarily, I have also joined paths ("fused") with many new, wonderful people who have entered my life through the Hyena Project.  And while I do not look forward to the day I have to say goodbye to my "Fisi Family", I do look forward to seeing my family in the United States again.

So it goes in our fission-fusion society.  Merry meet, and merry part, and merry meet again.

References (for more information):
http://eprints.bournemouth.ac.uk/900/1/grooming_final_No_highlight_2nd_rev_Anim_Behav.pdf
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3638441/
http://www.sciencedirect.com/science/article/pii/S0003347208001814
https://www.researchgate.net/publication/227873160_Fission_of_a_Spotted_Hyena_Clan_Consequences_of_Prolonged_Female_Absenteeism_and_Causes_of_Female_Emigration
http://www.princeton.edu/~icouzin/Couzin%20Current%20Biology.pdf
https://en.wikipedia.org/wiki/Fission%E2%80%93fusion_society