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As soon as you have anything to do with the gorilla the fascination of studying him begins to grow on you and you instinctively begin to speak of the gorilla as "he" in a human sense, for he is obviously as well as scientifically akin to man. - Carl Akeley
Accurately sums up my feelings about Black Friday. :-)
I saw the same animal doing this same behavior during my visit about two years ago. . .I was fortunate to have to anthropology grad students with me, who speculated that it was some sort of stress/displacement behavior.
He probably doesn't have an upset stomach. This is a common behavior of captive gorillas, referred to as R/R (regurgitation and reingestion). See Lukas (1999 Applied Animal Behaviour Science 63:237 for a relatively recent review.
He probably doesn't have an upset stomach. This is a common behavior of some captive animals, particularly gorillas (65% of gorillas in captivity demonstrate this behavior). It's referred to as R/R (regurgitation and reingestion) and has not been documented in wild gorillas, so probably has something to do with diet, boredom, or stress. See Lukas (1999 Applied Animal Behaviour Science 63:237 for a relatively recent review of this behavior.