Geographic Distribution and Habitat
The yellow baboon, an Old World monkey, is found in Africa, from its brown and prickly thorn scrubs and grassy savannas to its open woodlands and gallery forests. Located mostly in Central Africa, the yellow baboon can be spotted in the countries of Ethiopia, Kenya, Malawi, Mozambique, Somalia, Tanzania, and Zambia.
In places like Amboseli National Park, yellow baboons can be found traipsing through the expansive, semi-arid savannah filled with strands of acacia trees breaking up the open grassland.
Size, Weight, and Lifespan
Yellow baboons are sexually dimorphic; males often weigh around 55 lbs (25 kg) while the smaller females hover around 24 lbs (11 kg). To wrap your mind around this, an average five-year-old human child would weigh the equivalent of an adult male yellow baboon. Of course, the yellow baboon would be slightly smaller than the average human child at a length of 4 ft (121 cm) for males and 3 ft (91 cm) for females.
The yellow baboon has an average lifespan of 20 to 30 years in the wild.
It is not hard to imagine how the yellow baboon got its name—they are aptly dubbed for the yellow-brown fur that covers their bodies. However, yellow is not the only color that comprises a yellow baboon’s fur. They also have white-colored fur on inner surfaces like cheeks and limbs, much like the coloration of a human forearm.
Yellow baboons have surprisingly narrow, almost T-shaped, dark-colored faces. A pair of close-set, roundish eyes sits beneath a prominent, furry brow ridge. From there, their face protrudes with a long muzzle and wide lips. Their sallow cheeks almost give the impression that the yellow baboon is constantly sucking on a sour candy, though, more likely than not, they are storing grasses or seeds for later consumption. Dark, thin ears protrude ever so slightly from the thick fur on either side of the head.
Yellow baboons walk quadrupedally on long, slender limbs with their tail held up and curved away from the body. Their tails look “broken” in appearance—they stick straight up for a couple of inches and then fold backward like a deflated balloon.
Infant yellow baboons are born with a black natal coat that shifts to the yellow-brown as they age. Dark, thin ears protrude ever so slightly from the thick fur on either side of the head.
Yellow baboons walk quadrupedally on long, slender limbs with their tail held up and curved away from the body. Their tails look “broken” in appearance—they stick straight up for a couple inches and then fold backward like a deflated balloon.
Infant yellow baboons are born with a black natal coat that shifts to the yellow-brown as they age.
What Does It Mean?
When males and females have different characteristics (size, color, etc.) other than their reproductive organs.
Active during daylight hours
A line of descent traced from a female ancestor to a descendant; in other words, a “mother line.”
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Yellow baboons have been called eclectic omnivores because they are picky eaters when it comes to foraging, but vacuum cleaners when it comes to practically everything else. They rely on grasses, tubers, and two species of acacia: the fever tree and the umbrella tree. In gallery forests, yellow baboons consume all edible parts of the fever tree, from the inner pith to any rotten wood. Grasses and tubers aside, they are dietary generalists, meaning they consume a wide range of food consisting of fruits, seeds, flowers, gums, bark, buds, leaves, pods, sedges, beetles, ants, reptiles, birds, bird eggs, small vertebrate prey, and even other primates, like vervet monkeys and lesser bush babies. (See? Vacuum cleaners.)
Luckily for the yellow baboon, they can subsist on a low-quality diet, like grasses, for extended periods of time, which is useful if food is scarce or for venturing into dry terrestrial habitats like deserts, steppes, and grasslands.
Behavior and Lifestyle
Yellow baboons are generally ground-dwelling, diurnal animals. During their waking hours, they mostly forage for food and socialize. At night, they climb trees to slumber in a “sleeping grove,” which is usually located in the core of a troop’s territory and gives them the advantage of height when nocturnal predators come prowling in the night.
Between 7:00 and 10:00 a.m. each morning, the troop, which can be comprised of anywhere from 10 to 200 individuals, descends from the trees and ambles about the vicinity of the sleeping grove to socialize and groom one another. Eventually, they saunter into open grassland to forage, but they return to their sleeping grove in the evening.
Yellow baboons are cared for as infants by their mothers and are usually weaned around one year of age. They become completely independent between 12 and 18 months of age. Later, puberty occurs between the ages of five and six for females and between ages of four and seven for males. Before they reach sexual maturity, most males choose to emigrate from their natal troop. Then, as a male attempts to settle into a new troop, he must establish himself in the new male dominance hierarchy and rely on the females to support him. If they, for whatever reason, do not wish to mate with him, settling in could be difficult and unrewarding.
Yellow baboon’s top speed can reach 28 mph (45 km/h).
The yellow baboon’s scientific name, cyanocephalus, is a combination of Greek wods “kynos” (dog) and “kephalikos” (head). Its scientific name literally means “doghead,” which likely draws inspiration from the baboon’s long muzzle and quadrupedal stance.
Yellow baboons have cheek pouches that allow them to gather food and store it to eat later.
Daily Life and Group Dynamics
Yellow baboons live in very large, multi-male, multi-female troops that contain hierarchies and engage in group activities. Troop members sleep, forage, and travel together. The home range for any single troop is usually around 5,930 acres (2,400 ha), and the daily range of a troop is 3.6 miles (6 cm) on average.
Both males and females form a linear dominance hierarchy, in which the highest-ranking members have access to a larger amount of the troop’s valuable resources, such as food and mating opportunities.
There is a correlation between male dominance rank within the troop and mating success—larger, younger, and stronger males have a distinct advantage. Of course, there can be exceptions to this rule. Males can form reciprocal alliances with other males in order to subvert the normal dominance hierarchy. Essentially, two weaker—and usually older—males can join forces to out-compete one stronger male.
There are also “friendships” between male and female yellow baboons that often enhance a male yellow baboon’s chances to mate. The friendship also provides opportunities to share food, groom, and affiliate with particular females and their offspring. It is not uncommon for males to defend their female friends and their offspring during hostile encounters.
However, males do not maintain life-long social ties with their kin, so it is female kinship that forms the core and stability of yellow baboon society. Female baboons do not emigrate form their natal groups like males do, so they are able to form life-long associations. Within a troop, there is a dominance hierarchy of matrilines that is very stable over time because it is not continually challenged by the arrival of new females in the troop like males.
Yellow baboons are extremely sociable nonhuman primates and as such, they have developed complex forms of communication that range from threatening to friendly gestures. For example, if antagonized, a male might choose to shake some branches and yawn to display his sharp canine teeth to communicate visually, before resorting to physical fighting. If a situation does escalate into a physical dispute, friendly signals like lip-smacking and grooming can be used as reconciliation. Yellow baboons also utilize vocalizations and tactile communication.
Visual signals include, “social presenting” in which a female or juvenile displays her hindquarters to a male for mating purposes, “staring,” which is an aggressive gesture, “eyebrow raising”—an aggressive gesture that reveals the lighter fur in the area of the eyelid, “canine tooth display,” another aggressive gesture usually directed toward other males or a predator, “tension yawning” to display canines (see above), and “tooth grinding,” an aggressive gesture to threaten another male.
Auditory cues include “teeth chattering or grinding,” an action that can be heard when two males are threatening each other, and “lip-smacking,” which is a reassuring display as the lips are protruded and smacked together.
Vocalizations include “two-phase bark,” a wahoo sounding call that adult males direct toward feline predators or toward other males, “grunting” emitted by adult males as a threat, “screeching,” commonly emitted during aggressive encounters during any age or from either sex, “yakking,” a call emitted when retreating from a threatening animal, “shrill barking,” which is produced by all except adult males to indicate alarm, aspecially due to sudden disturbances, “rhythmic grunting,” which may be produced by all yellow baboons, except infants, when they wish to signal amicable intentions to another animal, and “dog-like barking,” produced when they become separated from the main part of the troop.
Tactile communication includes social grooming which reinforces social bonds and removes parasites and debris from the fur.
Reproduction and Family
Reproductive behavior in yellow baboons is closely tied to social organization—there is the potential for any male to mate with any female. The competition, therefore, is usually pretty fierce, with the larger, younger, and stronger males usually coming out on top. Most matings occur during consortships that arise when a male is able to maintain exclusive sexual access to a female through aggression toward potential rivals. Females have an estrous cycle of 32 days and mating is initiated by the female through social presenting.
Females reach sexual maturity at around five years of age and will give birth for the first time at around six years. The gestation period lasts for 180 days and females are more likely to reproduce every other year than annually.
After reaching sexual maturity, female yellow baboons reproduce consistently until old age and remain the primary caregivers to their dependent offspring. Most parental behavior is performed by the female—they nurse, groom, and play with their offspring—though that is not always the case. Infants are generally the focus of a great deal of investigation and attention, especially while they are still displaying their black natal coats. This is usually not a cause for concern for the mother, especially if she is a higher-ranking female. Lower-ranking females are often more nervous and restrictive and their apprehension is justified—lower-ranking females are often subject to harassment and, in extreme cases, kidnapping or infanticide.
Yellow baboons are an important link in the food chain of their range. As predators, they may affect the populations of prey through consumption or competition. As prey themselves, yellow baboons may in turn support predator populations.
They also occasionally pass seeds undigested through their bodies or carry fruit away from trees. They also undoubtedly aid in soil aeration from digging for roots and tubers.
Conservation Status and Threats
Yellow baboons are classified by the International Union for Conservation of Nature as Least Concern (IUCN, 2020), but that does not mean their species does not suffer threats. Their habitats are continually destroyed as a result of human activity. They become locally displaced whenever their foraging or sheltering sites are turned into agricultural land and they are commonly hunted and killed as a pest species after they’ve been caught raiding those same agricultural fields for food.
The yellow baboon is listed as Vermin under the African Convention.
They are also hunted as an important source of protein, the demand for which is only increasing as human population density in central Africa soars. Road mortality is causing local population declines as well as the species’ exportation from East Africa for medical research.
Despite some yellow baboon populations being locally displaced, overall this species remains widespread and common within its range. This is largely due to their opportunistic lifestyle and ability to adapt to an array of environments. The yellow baboon also lives in many protected areas like national parks, which helps maintain populations.
This species is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that trade in the yellow baboon should be carefully controlled to prevent it from becoming threatened in the future.
The African Wildlife Foundation is campaigning for wildlife conservation education and engagement to ensure that Africa’s baboons (there are five species total) do not become endangered.
Written by Rachel Heim, October 2018