More on Gorilla Behavior


Last week, I talked about facial expressions and some body movements, and what they mean for gorillas.  There are a few other behaviors that can sometimes be misinterpreted, so I thought I'd address those this week.  
Sometimes, you'll see our gorillas banging on the shift doors. I can almost guarantee that if you see this, it's probably one of our three males, and there are a couple of different reasons for this behavior.  More often than not, they are displaying on the shift doors in order to get the attention of another male on the other side of it. This is his way of showing off or trying to show how macho he is.  Kuchimba is the worst when it comes to this behavior.  It has always seemed that having some sort of a physical barrier between him and another male gives him some extra confidence that allows him to show off more assertively. So you’ll see him more than any of the others displaying on the shift doors—particularly the one between the dayroom and the yard, and particularly when Motuba is on the other side of it. Most of the time, Motuba shows how patient he is and ignores Kuchimba's displays.  But sometimes, he seems to get irritated by it, and will hit the door back. This behavior is one of my least favorites—it's very loud, to say the least!
One way that we provide enrichment is by switching the gorillas around the various exhibit spaces several times every day. For example, let's talk about what a possible day looks like for Louis (and every day is different for each of our three groups, so they don’t get bored of the same routine). He might spend the night in the dayroom, then shift down into one of their bedrooms for his first feeding.  Once I clean and set up the exhibits, I might send him into the trail for the morning, move him into the yard in the afternoon, then downstairs into his bedrooms for the end of the day and overnight. That's four moves in one day!

Sometimes you'll see the gorillas begin to get excited about switching exhibits, particularly because it means another snack or meal. You'll see Honi and Kuchimba anticipate these moves the most—Kuchimba gets especially eager to come inside after being in the yard for a few hours, and Honi is always hopeful that she'll be allowed to go into the trail for a little bit. When the gorillas are getting close to their next move, you might see them become more active and maybe even a little agitated if we are running behind. This is another occasion that Kuchimba can be seen banging on the shift doors. It's almost as if he's reminding me that he's there, ready to come in for lunch or dinner! When Louis wants to come inside, he will peer into the window in the door that accesses the keeper space, looking for me or whoever is working gorillas that day. Sometimes, he even knocks to get our attention. The gorillas can always see us setting up an adjacent exhibit space, so sometimes the fact that we are adding more food will get them excited and you'll see them start running around.
Our gorillas have a couple of other behaviors that draw some attention. Louis has become known for his head tilt, where he presses his ear to his shoulder. Honi can often be seen doing a behavior that we call "ear cupping," where she covers her ear with her hand. I like to compare both of these behaviors to hair twirling or nail biting in humans. Sometimes they do it as a comfort behavior, and sometimes they do it because they are nervous about something. But most of the time, this behavior is done subconsciously, for no apparent reason at all. 
One last behavior I want to discuss is when you see the gorillas throw up, and then eat it.  I know what you're thinking: "Ew! Gross!" And yes, to you or me, this would be absolutely repulsive. But in gorillas, we call this behavior "regurgitation and reingestion" (or R&R). There has been a great deal of research and there are many theories about why they do it, but in our gorillas, we tend to see them do R&R after they've eaten something that they really enjoyed. Hey, if it was good once, it must be just as delicious the second (or third) time around, right?  R&R also tends to be a learned behavior. You could have an entire troop of gorillas who never does it, but if a new gorilla comes in and does R&R, the others will often pick up on it.
I hope this continues to give you a little bit of insight into why gorillas do what they do!

Kristen Farley-RamboBy Kristen Farley-Rambo, Primary Gorilla Keeper