The largest primate in the world – up to 200kg/185cm tall for males, females up to 114kg/150cm (Behavior, p. 535).
Large belly to hind-gut fermentation of cellulose
Long, silky black hair, turning silver in older adult males
Confined to moist forest habitat by reliance on lush herbage (safari, p.419)
Sometimes show a preference for regenerating forest, as the break in the canopy allows for thick growth below (Behavior, p. 536).
Montane forests between 2800 and 3400 meters in the Virungas and Rwenzories, dominated by two types of trees, Hagenia abyssinica and Hypericum lanceolatum.
Tree canopy shades up to 50% of ground, the rest is a tangle of shrubs and vines up to 2 meters high (behavior, p. 536)
Restricted to the Rwenzories and Virunga Mountain areas of Uganda, Congo and Rwanda. Can be found in Uganda at Bwindi Impenetrable Forest and Mgahinga Gorilla Forest.
4-8 square kilometers. There is overlap between ranges, but troops will have an exclusive core area that will only be invaded when seeking a confrontation (beh, 538)
Daily movement for feeding averages 350 – 530 m in the Virungas (beh, 539) Members of the group may be spread over 100m when feeding. (beh, 540)
Primarily vegetation but, as they live at high elevations with low-quality browse, they supplement their diet with invertebrates (grubs and snails), bark, their own dung, and mineral-rich soil. (Behavior, p. 536).
Eat the leaves, roots and stems of about 58 different plants, and about 2% of their diet comes from the fruit of those plants.
9 plants make up 80% of their diets, 3 make up 60%:
Galium – (a scraggly vine) = 24% - 30%
Carduus afromontanus – (a thistle) = 10.5% - 37%
Cynoglossum – (a celery) = 8.5% - 20%
Also favor stinging nettle, blackberries and Veronica (a small tree)
Reproduction interval averages 4 years unless an infant dies, in which case a mother becomes receptive within a month (beh, p. 542)
Females may bear young before turning 9, but males are sterile until they become silverbacks at age 11-13. (beh, 542) (allows them to grow older in safety of natal group without being a threat to the resident silverback)
Females invite copulation (beh 542), and nearly always performed by the dominant male.
8 ½ month gestation. Birth usually occurs at night. Altricial young weigh about 2kg. Stay within arms reach of mother for first 6 months, after which they begin to be able to climb on their own
1-male harem system, including 1-5 unrelated females. Ferocious sexual competition accounts for great sexual dimorphism. (Behavior, p. 532)
Non-territorial. Females transfer and males emigrate. (Behavior, p. 537)
Groups are generally 2-20 individuals, largest recorded is 37, median in the Virungas is 6. (Behavior, p. 537)
Females transfer groups before breeding, usually around 8 years old. They may transfer again, but once they breed they will stay with that group (Beh. P. 537) Female transfers often happen during violent interactions between troops (beh, 538)
Earlier “wives” have higher rank than later ones. Rank allows them to stay close to the alpha male, which keeps them safer and closer to the best food. There is little interaction between females except to fight over grooming rights to the male, so the silverback is the only link for the whole group (Beh, 537)
Male offspring will emigrate starting at about age 11. They will generally not be able to establish their own harem until about age 15 or later (beh, 538)
Glands – 4-7 layers of apocrine glands under armpits of adult males which emit pungent odor under stress (detectable by humans 25 m away!). Apocrine and eccrine glands lubricate palms and soles (Behavior, p. 535)
Vocal: (92% from adult males) – beh p. 540
Roar: Only silverbacks and large blackbacks. Indicates stress or threat, followed by bluff charges or lunges. Rest of group will retreat behind silverback
Wraagh: Expresses alarm or surprise at the arrival of a human, thunder, alarms of other species, etc. Never accompanied by aggressive displays. Group scatters.
Hoot series: Low-pitched hoo-hoo-hooo repeated 2-20 times as prelude to chest-beating. Male advertising call maintaining intergroup spacing. Builds in volume, becoming longer and “plaintive” near the end. Usually a response to members of other groups.
Scream: Just what it says. Shrill, loud, repetitive. Can be vocalized by any group member and usually means conflict within the group
Question bark: Short call of 3 notes with first and third lower than the middle one (who are you?) usually alpha male in mild alarm maybe upon discovering a concealed observer.
Belch: soft grunting, rumbling, humming, purring, crooning, moaning, wailing, howling. Complex. Contentment, usually voiced by stationary gorillas.
Pig grunts: series of short, rough, guttural sounds like feeding pigs. Mild aggression and warning. Disputing right-of-way to food.
Copulatory panting: low-pitched but loud o-o-o-o continuously during copulation.
Facial: (p. 542)
Staring – annoyance. Eyes fixed and hard, brows in a scowl, head tipped down, lips pursed and slightly parted.
Tense-mouth face – anger. Mouth half to entirely open depending on intensity. Gums and teeth displayed, lips curled back. Opening and closing of mouth combined with screams and roars and often a mock charge.
Uneasiness – lips in with mouth compressed. Eyes shifty, head often up.
Play-face – Mouth open, but gums and teeth not showing
Create circular nests on the ground using vegetation for night and mid-day rests. Construction takes about 5 minutes. Mountain gorillas defecate in their nests and sleep on their dung. (beh, 539).
Most activity occurs in first 3-4 hours of the day (awaken at sunrise), followed by rest and then another feeding time around 3 p.m. Bed down at sundown. (beh, 539)
Ranges from about 35 - 60 years for males, 40-50 years for females
Nests and trails are apparently very easy to find. Number of nests indicates number of group members, and dung can be used to identify age and gender of each (Weber and Vedder).
Human poachers. Many also maimed by snares set in the forest.
Endangered by poaching and loss of habitat. Fewer than 800 still exist, with about half of those in Uganda.
Ourebia ourebi (Oribi) General Description/Adaptations:
My impression is that this animal has been studied in a number of different parks, but that the variation between results show much regional variation in behavior. I think the information I have gathered may be too generalized, so take all of this with a grain of salt and trust your own observations. Medium-sized, light-colored antelope with short, straight horns and black spots (scent glands) under the ears, white undersides and throat. Muzzle slants steeply from forehead. There are also dark preorbital glands in front of the eyes. It runs away with a characteristic “rocking-horse” gait. (Kingdon, p.388)
Females and young have a dark “forehead crescent.” (Estes, p. 58)
Size: (Kingdon, p. 388)
Head and body length: 92 – 140 cm
Tail length: 6-15 cm
Height: 50 – 67 cm
Weight: 12 – 22 kg
Fire-climax grasslands with reliable rainfall or grasslands that are kept short by grazing (by buffalo?). On floodplains, they prefer the less waterlogged areas where they can take cover behind termitaries or in woody growth. (Kingdon, p.389)
Avoids woodland and bush habitats. Prefers open mosaics with ecotones that allow for hiding. They may be dependent on burns during the dry season that stimulate new growth. Where fire is inhibited, they move during the dry season to low-lying areas that still have green growth. (Estes, p. 58)
Patchy, but widespread south of the Sahara. (Estes, p. 58)
Many varieties of grasses are eaten, as well as other herbs and the foliage of shrubs and trees. They will leave favored habitat occasionally to visit known mineral licks. (Kingdon, p. 389)
Water-dependent. (Walker, p. 146)
This is the only “dwarf antelope” that is primarily a grazer. They are the first to begin feeding on new growth after a burn. (Estes, p. 58)
There is some evidence that they may be water-independent, according to Estes. (Estes, p. 58)
Gestation is about 7 months. Young are precocious and hide for 3-4 days after birth. After that it follows its mother around with occasional retreats into hiding. They reach close to their adult size by 4 months. Females may conceive by 10 months and males become sexually active by 14 months (Kingdon, p. 390)
Most births happen during the rainy season. Calves remain mostly concealed for up to a month, and join mother full-time by 3 months. They can stand within 30 minutes after birth, and within 5 hours are able to jump small barriers. They begin eating small amounts of grass within a week. Males begin marking with preorbitals and have achieved adult coloration by 5 weeks, but are not fully weaned until 4-5 months. (Estes, p. 61)
They are associated with larger herbivores. The herds of larger animals help keep grass short through grazing and trampling vegetation and also probably draw off predation. In areas where larger herbivores have been reduced, oribi numbers also tend to decline. (Kingdon, p. 389)
Females are larger than males and move independently of the males. They will encourage the attentions of a single male, and will be intolerant of other males once she has chosen her mate. The two will each then defend the territory against others of the same gender. These pairings sometimes last for years. Territories adjoin communal grazing areas. Males daily delineate territory by scent marking plants and soil. (Kingdon, p. 390)
Most often found in pairs or small groups. (Walker, p. 146)
Associated with hippo, buffalo, cattle, zebra, topi and kob. (Estes, p. 58)
Oribis have been considered to possibly be an evolutionary link between monogamous/polygynous mating systems and solitary/gregarious social systems. They tend towards solitariness, but after fires they lose their cover and there is a safety advantage in herds. When startled by a predator, however, they scatter rather than maintaining a herd identity. Herding still has an advantage for spotting and warning about predators. (Estes, p. 58)
Tendency towards polygyny varies by location. Ugandan populations are about 50% polygynous. Other populations have been found to be almost 90% monogamous. (Estes, p. 59)
Female offspring may be allowed to remain in territory, although stranger females are chased off. Male offspring are chased away at adolescence. (Estes, p. 59)
They whistle to indicate alarm or to signal a move to another grazing area. Puffing, breathy whistles are used like birds’ “chip calls” to stay in contact. They bleat if pursued or captured. (Kingdon, p. 390)
Olfactory: The females are believed to excrete “attractants”, which keep males continually attentive. This causes the male to scent-mark relentlessly, perhaps leading to the development of 14 different scent-glands. This scent-saturation of the environment helps avoid confrontations between males, and also causes the female to habituate to the male’s scent as an essential attribute of her habitat. (Kingdon, p. 390)
Female crouching after defecating will stimulate a dunging ceremony with the dominant male: 1. The male sniffs the female’s anogenital region, causing her to move away. 2. The male marks a grass stem with his preorbital glands. 3. He sniffs her deposit. 4. He paws her deposit ‘vigorously’. 5. He urinates and defecates on the same spot. The other family members may also be stimulated to urinate and defecate on the same spot by the activity, but they will not paw the ground or mark with their preorbital glands. (Estes, p. 59)
Up to 14 years. (Kingdon, p. 390)
They are preyed upon by the usual cast of carnivore characters. Their avoidance tactic is to lay in hiding until the predator is close, and then flush and quickly reach a speed of 40 – 50 kph. They often stop and look back after running 200 meters or so. (Estes, p. 62)
Widespread and not endangered. (Kingdon, p. 390)
Colobus polykomos (Pied Colobus Monkey)
Distinctive, black-and-white monkey with a long, bushy white tail and white cheek hair. Long limbs, small head, four fingers on front hands. Has short, thin hair in lowland forests and longer, thicker hair in mountain areas. (Kingdon, p 26)
General info on monkeys:
The primates in Africa are all cercopithecoid monkeys except for humans, other great apes, and bushbabies. The cercopithecoid monkeys are divided into colobids (“thumbless monkeys”) and “cheek-pouch monkeys”, which are a more diverse grouping. The monkeys probably diverged from the great apes between 20 and 10 million years ago. The colobids were able to exploit dense forest because of an ability to digest plant parts (stems, unripe fruits and leaves) that the apes were not able to consume (being largely restricted to shoots and ripe fruits). Cheek-pouch monkeys adapted to feeding in open areas – they are able to quickly gather large quantities of food, and store it in their cheek pouches to be sorted out later. Baboons are an example of this. Cheek-pouch monkeys are also likely to be more extremely sexually dimorphic, as the males compete aggressively for available food sources and are more visible in open areas. (Kingdon, p. 17)
The adaptation of the hands shows that they evolved to be wholly arboreal and wholly vegetarian at an early stage. The hands are modified into curved ‘hooks’ for swinging, and the lack of a thumb means they cannot grab live prey and so choose to take vegetation directly into their mouths. The pied colobus is more highly evolved that the red colobus, and so is able to subsist on lower-quality vegetation. This gives them an advantage. (Kingdon, p. 18)
The digestion of colobus monkeys has adapted in a similar way to the ruminants. They are able to hold 1/3 of their body weight in their stomachs, which is then processed during long sleeping and resting periods during the middle of the day. Digestion is assisted by bacterial fermentation, like ruminants and other herbivores. (Kingdon, p. 19)
They have a two-chambered stomach, with fermentation happening in one and then acid digestion in the other. The fermentation process also detoxifies leaves, seeds and fruit that would otherwise be poisonous. This allows them to feed with less competition from other primates. (Estes, p. 520)
Newborns are entirely white, with pink faces. (Estes, p. 523)
Size: (Kingdon, p. 29)
Head and body length: Female 48 – 65 cm; Male 54 – 75 cm
Tail length: 65 – 90 cm
Weight: 10 – 23 kg [ in Uganda, Males 9-14.5kg; Females 6.5 – 10 kg]
Colobus monkeys are restricted to the moist, tropical and montane forest belt. Cheek-pouch monkeys are much more widely distributed and are found in all habitats except the Sahara, although they attain the greatest diversity in forested areas. (Kingdon, p. 17)
‘Colobe’ is Greek for ‘cripple’ – they were given this name due to the lack of thumbs. (Kingdon, p. 18)
Pied colobus are able to live in more degraded forests than red colobus due to their more specialized digestive system. (Kingdon, p. 30)
In Kibale National Park in Uganda, there is only a 7% overlap in food species between the red and the black-and-white colobus. Even on these common species, they eat different stages of growth. (Estes, p. 521)
Size varies from about 5 hectares to about 25 hectares. These territories have hard edges, and the small size allows for very high concentrations of these monkeys, ranging up to 500/sq. km in Kenya and Tanzania. (Estes, p. 525)
They are often characterized as ‘leaf-eaters’, but actually eat a wide range of difficult plant material, including seeds, seed pods, petioles, and unripe fruits, and avoid fresh, colorful fruits. There are also able to process leguminous plants that are poisonous to most other animals. The Guereza pied colobus, in particular, is able to process hard, old leaves which allows them to survive long dry seasons. (Kingdon, p. 18)
In Uganda, 40% of the guereza’s food comes from one tree, Celtis durandii. This is the only monkey that eats the leaves of this tree, eliminating competition. Figs may also constitute up to 25% of their diet at certain times of the year. (Estes, p. 524)
Six month gestation. Births happen more often in the rainy season, spaced about 20 months apart. Females mature at 4 years, males at 6. Infants are large at birth, but develop slowly. The young lose their white coloration by 14 – 17 weeks. They are carried by females for up to 8 months, but are able to move on their own beginning at about 5 weeks. At two months young are playing with each other and eating some leaves. By four months they are playing and exploring on their own and are only carried when the whole troop is traveling. Mothers largely ignore their offspring by 23 – 25 weeks (Estes, p. 530)
Territorial, with a single dominant male. They are primarily sedentary, with small, non-overlapping home ranges. Average troop size is 9 in Uganda, with a range of 2 – 15. If a solitary monkey is seen, it is most likely a sub-adult male that has recently been chased out of its natal troop and is looking for a partner or a bachelor troop. (Estes, p. 524)
Dominant males will occasionally allow other adult males if they act submissive, but it is not uncommon for takeovers to be instigated by these males, sometimes followed by infanticide of the first alpha’s offspring. (Estes, p. 525)
Although home ranges are generally completely exclusive, one study of a troop in Kibale National Park showed that there were several other troops that would occasionally be within their boundaries. The study troop was seen to be completely dominant over the other troops, though, and the researchers theorized that the unusual traffic was due to the proximity of a swamp where several troops came to feed. (Estes, p. 525)
Troop members stay in very close proximity while feeding, usually the whole troop would be contained within an 18-meter diameter circle. Females and young stay closest together, with peripheral males keeping the most distance. They participate in an unusually high frequency of social grooming (up to 6% of daily activity). The dominant male rarely participates in this grooming. Grooming peaks during the mid-day rest period, during the early morning, and when rival troops are nearby. (Estes, p. 525)
One of the most unusual behaviors of black-and-white colobus is the willingness of mothers to allow other females to handle their very young offspring. They are rarely handled by their mothers or other females after they reach 4 months of age. (Estes, p. 526)
The Matriarch leads troop movements, except for challenges to rival troops, which are led by the dominant male. (Estes, p. 526)
Vocal: (Estes, p.527)
Roaring: This is supposedly only emitted by dominant males, especially early in the morning. It is a low, resonant croaking sound with a rolling “r” that can be heard for over a mile. They may call like this for up to 20 minutes. It can be used either for advertising the male’s presence or as a threat display.
Snorting: Explosive sound, emitted by all except infants, to express alarm. Often a prelude to roaring for dominant male.
Snuffling: A sound like a pig rooting. Females and young will emit this sound during intra-troop conflict such as a female pushing away an infant that wants to nurse, or in aggressive interactions between females and males.
Squealing: Adult females and young emit this as a signal of strong distress.
Soft grunting or purring: Alert call for short-distance communication such as a signal for troop movement. May also signal a predator nearby.
Tongue-clicking: Adults use this as a prelude to an aggressive interaction. Milder than snorting.
Jumping around and crashing through branches may be used by dominant male to show size and strength. Sometimes joined with roaring. (Estes, p. 529)
They spend the middle of the day almost totally inactive or asleep, like ruminants. (Kingdon, p. 17)
These monkeys leave their sleeping trees well after sunup, then proceed to the canopy where they sunbathe in sight of neighboring troops for up to an hour. They travel regular arboreal routes to get to their feeding trees, then feed until it gets hot. They will rest and groom until the evening, at which point there is another activity peak until about one hour before sunset, when they return to their sleeping trees. (Estes, p. 526)
Chimps, humans, leopards, crowned hawk-eagles.
They are not considered endangered, but their range has been seriously restricted by habitat loss and hunting. The mountain populations have very valuable pelts and may be hunted to extinction since there is no protection for them under IUCN. (Kingdon, p. 30)
Crocuta crocuta (Spotted hyena) General Description/Adaptations:
Dog-like with black muzzle and black tail-tip. Body color is brown and slate in young, tawny in old. Spots throughout neck, body and legs which fade with age. (Kingdon, p. 261)
Have “hermaphroditic” sex organs – female clitoris mimics a penis and has a foreskin. Also paired swellings in the scrotal area mimic testacles. (Kingdon, p. 261)
Most carnivores waste up to 40% of their kills. Hyenas don’t. (Estes, p. 337)
Have evolved long necks to compensate for long legs (so mouth can reach the ground without the hyena having to kneel. The hindquarters slope down because they need tall spinal processes at the shoulder, which is the primary pivot for all gaits. (Kingdon, p. 258)
Skulls are deep and wide to accommodate huge chewing and neck muscles. Teeth are likewise adapted for breaking bones and tearing through thick skins. Their ability to digest bones and teeth distinguishes them from aardwolves and all other carnivores. They can digest bone in a matter of hours. (Kingdon, p. 258)