Table 1 Environment, diet and interspecies contacts for gorillas and chimpanzees in southeastern Cameroon and in the European zoo.
Study site | Chimpanzees Pan t. troglodytes | Gorillas Gorilla g. gorilla | Sources | ||
|---|---|---|---|---|---|
Group size | Cameroon | 9 | 9–12 | Number of nests during feces sampling | |
Zoo | 4 males and 3 females | 1 adult male, 4 females, 5 infants/juveniles | Direct observation | ||
Environment | Cameroon | Density | 0.17 ind/km2 | 2.5–3 ind/km2 | |
Habitat preferences | Mainly in mixed mature forests with closed canopy | Mainly in open canopy forests with dense herbaceous vegetation | |||
% of land cover represented by rivers | ~ 0.1% of the area | ||||
Zoo | Indoor enclosure | 215 m2 Straw and wood chips on the ground Various horizontal and vertical structures | 115 m2 Straw and wood chips on the ground Various horizontal and vertical structures | Interviews with zoo zookeepers and direct observations | |
Outdoor enclosure | 7000 m2 Herbaceous vegetation: herbs, iris, water daffodils, bramble Trees: goat willow, wild cherry, hornbeam, oak, chestnut Water channel around the island | 5000 m2 Herbaceous vegetation: herbs, bramble, water daffodil, rushes Trees: oak, maple, chestnut Water channel around the island | Interviews with zoo zookeepers and direct observations | ||
Diet | Cameroon | Diet composition | Mainly fruits Leaves, shoots, pith Occasionally mammals, insects and honey 132 plant species | Mainly leaves, shoots, pith and roots but increasing of fruit consumption when fruit availability is higher Occasionally insects 150–180 plant species | |
Geophagy | Regular/Frequent | Frequent | |||
Charcoal consumption | Ash consumption reported once | Not reported | |||
Zoo | Meal organization | 4–7/day. All individuals eat together | 4–7/day. Separate: silverback eats alone; small groups composed of adult female and her offspring | Interviews with zoo zookeepers and direct observations | |
~ 80% vegetable matter and 20% fruits 15–20 different food species/preparation | Interviews with zoo zookeepers and direct observations | ||||
Food provided—Morning | Salad, carrot, apple, "Old World Monkey" chow, Rice and one fruit (banana, orange, kiwi, pear …) | Salad, celery, turnip, fennel, apple, cabbages, “Old World Monkey” chow Branches (mainly hazelnut) for bark, fruits, leaves | Interviews with zoo zookeepers and direct observations | ||
Food provided—Day time | Vegetables only | Cucumber, endive, carrot | Interviews with zoo zookeepers and direct observations | ||
Food provided—Evening | Salad, apple, carrot, bell pepper, 1 fruit (banana, orange, kiwi, pear …) | Salad, leek, tomato, bell pepper, broccoli, 1 fruit (varied) Locally-made biscuit (wheat flour, soy flour, oatmeal, vitamins, salt) Large branches (bark) | Interviews with zoo zookeepers and direct observations | ||
Food provided—1 times/week | Cold weather: Tea, vegetable broth Hot weather: grenadine syrup Hard boiled egg Cooked meat (chicken, turkey) | Almonds, other nuts and seeds | Interviews with zoo zookeepers and direct observations | ||
Food provided—Occasional | Seeds (wheat, maize, sunflower, almond, peanuts, walnuts, oatmeal) Flour worms Boiled potatoes Bread | During winter: enrichment with wheat flour or honey in enclosure | Interviews with zoo zookeepers and direct observations | ||
Opportunistic consumption from the island | Spring: Wild cherry (young leaves, fruits), Hornbeam (bark) Autumn: Oak (Fruits), Chestnut (Fruits) All seasons: iris (leaves) Mixed piece of fruits with straw, herbs or dried leaves to masticate as a kind of “chewing gum” Geophagy (rare) | All seasons: herbs, rushes (leaves), water daffodil (leaves), bramble (leaves and fruits when available) | Interviews with zoo zookeepers | ||
Charcoal (from burned twigs/trees) Water consumption from channel | Interviews with zoo zookeepers | ||||
Contacts with humans, other NHPs species and prey | Cameroon | Physical contact and close proximity | With humans: Hunting/Injuries/Pets, likely low influence on great ape intestinal microbiome Potential conflicts between gorillas and chimpanzees (rare) | Semi-structured interviews with local populations | |
Potential hunting behavior (of monkeys, duikers, rodents and pangolins) | No mammal hunting reported | (based on observations at Lope National Park, Gabon and Nouabale-Ndoki National Park, Republic of Congo) | |||
Environmental contact and spatial overlap | Spatial overlap with humans and 7 other NHP species: Cercopitecus nictitans, Cercopithecus cephus, Cercopithecus sclateri, Cercopithecus neglectus, Cercocebus agilis, Colobus guereza, Lophocebus albigena Feeding on the same trees or in the same areas between gorillas and chimpanzees when wild mangoes are highly available | Semi-structures interviews with local people | |||
Zoo | Physical contact and close proximity | Veterinary care Daily close proximity between zookeepers and great apes (separated by fences/cages) Medical Training | Interviews with zoo zookeepers and direct observations | ||
Frequent physical contact (almost daily) with zookeepers through the grid (mutual grooming and play) | No physical contact | ||||
Environmental contact and spatial overlap | Cleaning procedures: Every 3 days Hot water at high pressure New straw No bleach | Island shared with Colobus guerez and Cercopithecus ascanius Cleaning procedures: Every 5 days Scrubbed with water and soap New straw No bleach | Interviews with zoo zookeepers and direct observations | ||
High probability of human contamination with fomites through foods, enrichment and structures Water channel shared by 32 other NHP species of zoo | Interviews with zoo zookeepers and direct observations | ||||
