Geographic Distribution and Habitat
Malbrouck monkeys are native to central and south-central Africa and inhabit the swampy, savanna, and montane forests of the Democratic Republic of Congo, Namibia, and Zambia’s Kafue National Park. Closely related and similar in appearance, they are sometimes classified as a subspecies of the vervet (Chlorocebis pygerythrus) or inaccurately referred to as “vervets” or “grivets,” the latter being another closely related species of the Chlorocebus genus. It is primarily their region of origin that differentiates them from their vervet and grivet cousins.
A large part of their territory spans “miombo” and “mopane” woodlands at altitude of 1,600–3,200 ft (500–1,000 m). Some groups are found at sea level near the mouth of the Congo River; others are found at altitudes of up to 5,200 ft (1,600 m) on the Angola Plateau. Throughout the species’ entire territory, temperatures oscillate between 64 F and 75 F (18–24 C) all year; even at the highest altitudes, it never goes below 41 F (5C). The annual rainfall varies from 68 in (1,750 mm) near the equator to 17 in (450 mm) along the Namibia-Angola border and there is only one dry season lasting from June to September.
Size, Weight, and Lifespan
Male malbroucks are about 30% larger than females. They weigh between 9 and 17 lb (4–8 kg); females average 7 to 11 lb (3.5–5 kg). Males are 17 to 24 in (42–60 cm) tall versus just 12–19 in (30–50 cm) for females.
Since malbroucks are little studied, there is no specific information regarding their lifespan. However, based on the general lifespan of the Chlorocebus genus, it is safe to assume they live between 15 and 30 years.
These slim monkeys have long limbs and a long tail. Their body is covered in long soft and wavy olive-grayish fur. Their underparts are white. Their black faces are framed by the white fur of their eyebrows and jowls. They have thin slanted nostrils and thin lips. Their eyes are a warm brown color. Their chest is white. Males are easily distinguishable because they have bright blue and red genitals. They also have whiskers around their ears. Their feet are dark in color. The tip of their tail is black, while the underside is gray with some red at the base.
Malbroucks have a rich and diverse diet that includes lots of vegetation, fruit, seeds, flowers, gums, and the occasional prey (like lizards and invertebrates).
Foliage, gums, and even bark of acacia trees make up 70% of their nutritional intake. While foraging, they stuff food in their cheek pouches for later consumption.
In Angola and Zambia, malbroucks have been observed consuming a lot of sugar plums, buffalo-thorn leaves, the fruit of the West African ebony (also known as monkey-guava), marula plums, and different kinds of figs, as well as acacia seed pods.
Behavior and Lifestyle
Malbroucks are diurnal and semi-terrestrial. They live in groups made of multiple males and females, which can average up to 50 individuals, with as many adult males as there are adult females. Smaller groups include one male, one female, and their offspring. Groups composed of only females also exist.
Males transfer from their natal group at maturity, and sometimes join groups that their male siblings have already joined. It is suspected that such strategy would enable them to create successful coalitions, as males gain power through force and conflicts with other male and female residents. Because males gain power by force, the offspring of dominant and non-dominant females have equal opportunities when they join a new group.
Inter-group encounters may be friendly, but when conflicts arise, all members of the group (except the youngest) engage in the fight.
Malbroucks rise at dawn and the group travels on foot to different foraging sites in large open-space areas. At sunset, they settle in for the night and select trees or large shrubs, preferably located along rivers or other water sources. They tend to avoid areas where guenon species are found.
Malbroucks communicate with vocalizations; these include alarm calls to warn members of the group of imminent danger. They also use body postures and facial expressions. Avoiding eye contact, for instance, is a way to indicate that one individual is submissive to another. Grooming and social play are important to maintain cohesion within groups.
Agonistic behaviors include loud vocalizations, chases, and displays. Males engage in “spay-legged” displays to expose their brightly colored genitalia to discourage outside males from trespassing. These displays are especially common during mating season.
Based on few existing records, it seems that most malbrouck births occur between August and October after a gestation of five and a half months.
Savanna monkey females, probably including malbroucks, do not show external signs of estrus, like genital swelling or color changes. Dominant females have mating priority over other females. They continue to mate during the first half of pregnancy, possibly to encourage males to participate in infant care. Females help each other in the rearing of their offspring. This is referred to as “allomothering.” The bonds between mothers and daughters are very strong.
Newborns weigh approximately 14 oz (400 g) and are a soft dark brown color—except for those born in Angola, who are a light gray color. Why color varies in different regions is unknown.
Malbroucks play an important ecological role as seed dispersers. As such, their presence in their habitat is important to maintain forest biodiversity.
The malbrouck monkey is listed as Least Concern by the International Union for Conservation of Nature Red List (IUCN, 2019). There are currently no known threats to the species that are likely to result in substantial population declines. However, this species has rarely been studied and no thorough assessment of its range and numbers have been published in recent years. They are present in modified environments and can live in close proximity to human cultivated areas; this shows some degree of adaptability.
Being in proximity to humans increases risks for these monkeys. Infants and juveniles are sometimes captured and kept or sold for the pet trade. They may also be killed as pests, especially in Angola and Zambia, where farmers retaliate against them when these monkeys raid corn, sorghum, and fruit crops.
The spread of diseases both in humans and primate populations increases as savanna monkeys, including malbroucks, live in closer proximity to humans. These include HIV/AIDS, ebola, simian foamy virus, polio virus, and the transmission of gastrointestinal parasites.
Apart from humans, the natural predators of these monkeys are yellow baboons, dogs, lions, leopards, cheetahs, servals, caracals, brown hyenas, spotted hyenas, black-backed jackals, martial eagles, African crowned eagles, pythons, and crocodiles.
There are no specific programs for the protection of this species, which is present in several protected forests including Luando National Park in Angola, Chobe National Park in Botswana, Kafue National Park in Zambia, and Etosha National Park in Namibia.
- www.africanwildlife.com – African wildlife guide
- Primates in Perspective – Christina J. Campbell, Agustin Fuentes, Katherine C. MacKinnon, Melissa Panger, Simon K. Bearder – Chapter 15 “The Guenons (Genus Cercopithecus) and Their Allies – Behavioral Ecology of Polyspecific Associations – Karin L. Enstam and Lynne A. Isbell
- Savanna Monkeys, The Genus Chlorocebus – “Behaviorial Ecology of Savanna Monkeys” – Trudy R. Turner, Christopher A. Schmitt and Jennifer Danzy Cramer
- Savanna Monkeys, The Genus Chlorocebus – “Ethnoprimatoloty and Savanna Monkeys” – Trudy R. Turner, Christopher A. Schmitt and Jennifer Danzy Cramer
- Mammals of Africa – 2013 – Chlorocebus – Colin P. Groves and Jonahan Kingdon
- Mammals of Africa – 2013 – Vol II – Chlorocebus cynosuros – Malbrouck monkey – Esteban E. Sarmiento
Written by Sylvie Abrams, January 2020