Living the Bachelor Life - Understanding Gorilla Social Structure

An important social arrangement for gorillas is the bachelor group. A typical family has only one mature male and many females with offspring, so there will be quite a few males who find themselves without any lady friends. These males can either live a solitary life or hang out with other single males. In the wild, bachelor groups are usually loose associations, however, sometimes males will bond and form more permanent friendships.

In zoos, bachelor groups are planned out well in advance. The Association of Zoos and Aquariums’ (AZA) Gorilla Species Survival Plan (SSP) monitors the population of gorillas and makes recommendations for social groupings. There are a number of factors (primarily genetics, age and housing availability) that determine which individuals will be placed together, but generally bachelor groups are made up of at least three males of similar age; groups are usually formed while the animals are still young (often as young as five), so that they grow up together and form strong, lifelong friendships. Bachelor groups allow non-breeding males to live healthy, social lives while minimizing competition and conflict.

At six, Leom is close to the age that Bo and Bakari were when their bachelor group was selected, and he is relocating to an AZA-accredited zoo in Texas as part of an SSP recommendation. Our three bachelors are well bonded and much older than Leom, so he wouldn’t be accepted into their group. He will be greatly missed by his caretakers and OKC Zoo guests, but will thrive in his new bachelor group! Similarly, 10-month-old Fin will also one day likely go to a bachelor group of his own.

Bo and Bakari both came to OKC Zoo when they were juveniles to form a bachelor group with OKC Zoo-born George. For a time, they lived with several females and an adult male, Tatu, who served as a great role-model demonstrating proper adult male behavior for the three juveniles.When Tatu passed away in 2016, the bachelor group was well-established. George, Bo and Bakari are now 15, 13 and 12 years old and transitioning from juveniles to silverbacks. During this adolescent stage, males tend to be a bit more territorial and aggressive with one another. Caretakers are monitoring them closely and are ready to give them more space and privacy if their behaviors indicate it is needed.

Male gorillas continue to develop physically up until about age 15, but may not be behaviorally mature until a few years later.  Adult characteristics include a large sagittal crest (a bony bump on the top of the head that supports their large jaw muscles), large canine teeth, broad shoulders and silver hair on their back and legs. This is where they get the name “silverback.” At this age, males begin to form families of their own. The lead male of a group is usually no longer tolerant of other males when they reach adolescence. In the wild, such males usually choose to leave the group voluntarily, but sometimes they can challenge the lead male and (if successful) take over the group or (if unsuccessful) be forced out of the group by the leader. 

-Laura K. Lynn, caretaker - apes

Photo credit: Andrea Johnson

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