Chacma Baboon Behavior

I figured not everyone knows all the intricacies of primate and baboon behavior, so this blog post highlights the animals I have dedicated my summer to study. I spend almost every day with chacma baboons (Papio ursinus), a species that occurs in the countries of Southern Africa below The Democratic Republic of the Congo and Tanzania. They are part of the old world monkey family (Cercopithecidae), which includes monkeys that are found across Europe, Africa, and SE Asia. Specifically, I research Cape Chacma Baboon populations (Papio ursinus ursinus) that exist on the Cape Peninsula at the tip of South Africa.

Baboons, by definition, are a type of generalist organism. This means that they have omnivorous diets and can survive off of a wide array of foods. In addition, although chacma baboons are typically found in wooded highlands, grassland steppes, and savanna habitats, they are capable of thriving in many different environments. Baboons are also highly and explicitly social. They live in large multi-male and multi-female troops (one of the troops I study is about 70 individuals). This creates a problem from a management standpoint because large groups of baboons can readily and successfully invade anthropogenic environments, initiating strong human-wildlife conflict. To make matters worse, baboons possess a high level of intelligence as primates. They can problem solve quickly in order to raid and exploit human resources. Baboon troops can communicate with each other through oral language, visual gestures, and tactile signals. Baboons have also been found to be capable of orthographic processing skills, which account for the ability to read. All of this together heightens the probability of human-wildlife conflict. But that is an entirely different (and very controversial) story for another time.

            Chacma baboons are one of the largest of all monkeys, with males weighing around 46-99 pounds and females weighing 26-55 pounds. They are sexually dimorphic, meaning that male and female adults differ in their morphology and appearance. Adult males are larger in size and have long, obvious canine teeth that they like to reveal on practically every occasion. Males also have slight manes of fluffy fur framing their faces. Females are much more petite and exhibit large sexual swellings that wax and wane throughout the month. I’m beginning to determine whether a baboon is male or female just by looking at their faces. Adult and juvenile chacma baboons have a gray-brown fur color, while infants are covered in fine black fur. The cape chacma baboons have dark black feet and heavier bodies than some of the other members of the species.

 

Probably what intrigues me most about these monkeys is their sociality. Chacma baboons have intricate and complex social organizations that include dominance hierarchies, friendships and coalitions, adoption of orphaned infants, alloparenting, collective foraging, and infanticide. After watching them for hours on end, it is hard not to become engrossed in the every day drama of baboon life.

Of central importance to the baboons is dominance. Female baboons remain with their natal troops and inherit their social ranks maternally. Offspring of female baboons are automatically ranked the same as their mother and kinship ties are ultimately very strong. Sometimes, if one baboon juvenile torments another juvenile, the entirety of both lineages of the two offspring will become involved and the skirmish escalates to a mass chaos event of baboon screaming and chasing. Female kinship forms the core of baboon society. Male baboons, conversely, disperse into new troops before reaching adulthood and compete for dominance rank. Males will aggressively interact with other males to establish dominance. For males especially, there is a direct correlation between their ability to compete with other males and their reproductive success. Males therefore have intense competitions over sexually receptive females. Many times, males will form friendships with female baboons in the hope that they will have a higher likelihood of mating with her. Males will groom, share food, and spend increased affiliative time with female “friends.” Females in turn, prefer their male “friends” as mates. One thing in particular I am studying is male consortships of females. Consortships occur when a male attempts to gain exclusive access to one female. Females may consort with multiple males before ovulation, allowing them some mate choice. Although, from what I have observed, many females will mate with one male after another all day long (there are a couple particularly promiscuous females we have identified). Mating is female initiated.

Hamlet likes to play with the infant Bonapart

Female baboons primarily care for their offspring. High ranking females may be less restrictive with their infants than lower ranking females, allowing the babies to run off and play more often. Other females within the troop may alloparent (parenting behavior from individuals other than the mother or father) infants, holding and grooming them. Chacma baboons have also been found to show adoption of orphaned infants. Another female will take the baby in, protect it from harassment, and care for it like a mother. There appears to be little paternal care with chacma baboons, although I have seen the dominant male in one of our troops playing with a young infant baboon who is presumably his child several times.

Our baboon troops range in the lower levels of the Tokai Forest on Elephant’s Eye Mountain. Their range extends into human properties, horse stables, and picnic areas at the base of the mountains. Personally, I prefer when they are in the forest and shrublands on the mountain slopes, but part of my study involves baboon management and hence their behaviors in human environments are quite significant. The baboons tend to sleep in the Monterey Pine trees during the night, and then descend from the branches to the ground to forage for the remainder of the day. We follow the troop until sunset, just before they scale the tree trunks for the evening. I must say that baboons are incredibly fascinating to watch. Their social systems and behaviors never cease to amaze me.

Sources:

http://animaldiversity.ummz.umich.edu/accounts/Papio_ursinus/

http://www.iucnredlist.org/details/16022/0

http://www.pbs.org/wnet/nature/episodes/murder-in-the-troop/inside-chacma-baboon-society/2051/