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Friday, September 8, 2017

An unusual gorilla adoption

Posted by: Milou Groenenberg, Mbeli Bai Gorilla Study, a Woodland Park Zoo Wildlife Survival Fund project

At Mbeli, we follow the interesting lives of many different gorillas. One of our most fascinating stories is that of George’s group. George was already an adult silverback when the Mbeli Bai Study started in 1995. He acquired his first females in 1998, and became a successful harem holder, siring a total of 19 offspring. One of the females in his group, Leah, became famous worldwide for the first observation of tool-use by wild gorillas. From 2004 onward, George’s group slowly started to reduce in size as he lost female after female. From 2012 onward, George started to mingle with another group: Morpheus’s.

Morpheus (back), George (front) and Jockey (center, offspring of Morpheus) are tolerating each other in close proximity as their groups are mingling in the bai. This occurred regularly in the period between 2012 and 2016, until George was last seen. Photo courtesy Marie Manguette. 

There appeared to be some sort of unique fission-fusion dynamic going on in which the groups would sometimes visit the bai together, and other times, separately. This development was highly surprising as western lowland gorillas, unlike their mountain cousins, are generally very intolerant of other adult males within the same group. George still had one reproductive female (Bessie) in his group as well as dependent infant, Obama. The risk for infanticide or sneaky copulations could be lurking around the corner.

Obama is George’s youngest infant; he was still dependent when George’s group first started to mingle with Morpheus’s group in 2012. He was four years old when Morpheus accepted him and his brothers in his group. Photo courtesy Marie Manguette.

Morpheus is quite a special silverback himself. His physical appearance stands out because of a massive drooping lower lip. Morpheus has been known to the study since 2003. He had a modest breeding group and sired one of the five twin sets observed at Mbeli (Neo and Niobe). By 2011, he had lost all his females and became a single dad. His older sons were known to be some of the bravest (or craziest?) gorillas in our population; chest beating to anything from sitatunga, to cobra, and even elephants.

Morpheus is the silverback gorilla who ‘adopted’ George’s kids in 2016. His interesting physique, including a large, drooping lower lip, makes him easily identifiable. Photo courtesy Marie Manguette.

It was sad to see how George slowly became weaker and older, turning feeble and skinny. The frequency in which he mingled with Morpheus increased during this time. He was last seen in March, 2016, and is assumed to have passed away at the respectable age of 41 years. His faithful ‘wife’ Bessie has also not been seen since.

Silverback George is seen here at age 40, standing in a pool in the bai whilst feeding in bipedal position. Photo courtesy Milou Groenenberg

Interestingly, Morpheus took mercy upon George’s kids, the little four-year-old Obama, the handicapped Booker, who cannot use his left hand, and the handsome young silverback Custer. These three fellows have been visiting the bai with Morpheus ever since they lost their dad. Morpheus defends his adopted children as vigorously as his own, which was exemplified during a recent visit when a solitary silverback came too close to Custer, after which Morpheus ignited in a raging session of chest beats and splash displays.

Video: Jockey bluff charging KotickJockey and his adoptive brother showing off against an adult silverback. This video, although a bit wobbly, shows an interesting interaction between Custer, George’s biological son (right back), Jockey, Morpheus’s biological son (left front), and an adult solitary silverback named Kotick (right front). Custer can be seen ‘tight-lipped’ (a type of agonistic display) in the beginning of the video, after which suddenly Jockey decides to bluff charge through the water which startles Kotick.


These extraordinary developments in the group’s composition raise interesting questions: Were Morpheus and George related? Would Morpheus accept, raise and protect non-relatives? Did George have an intention for the future protection of his offspring when he started to mingle? For how many of the younger gorillas in our current non-breeding groups can we safely assume that the silverback is their biological father? How often do these alternative group compositions occur? What implications can such information have on management in human care? All these and more are the interesting research questions we will continue to follow at Mbeli Bai.


About the project
Woodland Park Zoo has supported the Mbeli Bai Gorilla Project since 2001 through our Wildlife Survival Fund. Since the establishment of the Mbeli Bai Gorilla Study in 1995, the focus has been on the continuous monitoring of the visiting western lowland gorilla population to gain insights into population dynamics, demography, social structure, and behavior. This information is crucial for assessment of a population’s vulnerability to threats, predictions of their ability to recover from decline, and formulation of effective conservation strategies. In 2016 alone, with regular monitoring of the bai, data has been obtained on 26 gorilla groups and 12 solitary males, totaling 200 individuals.

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