Ecology The gorilla lives in humid rainforests along the equator. Gorillas eat plants that grow only in areas that receive intense sunlight exposure. Mountain gorillas live in forests between 9200 and 11,200 ft (2800-3499 m) and occasionally are found in meadows at around 13,000 ft (4000 m). Eastern lowland gorillas can also be found in the mountains between 6600 and 8000 ft (2000-2500 m).
The mountain gorilla feeds on 58 different kinds of plants in 7 different vegetation zones. There are 9 of these plants that make up 80% of their food intake and just 3 species of plants (vine, thistle, and celery) make up 60% of the gorilla's diet. Gorillas also eat roots, fruits, shoots, leaves, bark, pith, and grubs which grow on rotting wood. A unique thing about gorillas is the fact that they do not share their food with others.
Activity The gorilla is a diurnal mammal with a fairly consistent daily schedule. On cold or rainy days, the mountain gorilla will stay huddled together for warmth and tend not to get anything accomplished while other gorilla will spend 30% of their time feeding, 30% traveling, and 40% resting. On average, the gorilla will travel approximately 380-600 yd and up to 1170 yd (1 km) daily in other equatorial regions.
Social Systems Gatherings or selected groups of gorilla are called harems. Harems are nonterritorial groupings of gorillas which have 2-12 members in each. A harem consists of 1 mature male, 1 young male, 3 wives, and 2 offspring. A harem's home range is typically 1.5 to 3 sq. mi (4-8 sq. km), but in other areas can be as large as 7-9 sq. mi (20-25 sq. km).
Reproduction The gestation period is 8.5 months and there is a 4 year interval between births. Researchers believe that part of the reason why gorillas are endangered is because of the high mortality rate of the young. In some regions the mortality rate is as high as 46% which means that if a male lives for 40 years he will only leave 2 to 6 living offspring or 10 to 20 if he lives to be 50 to 60 years of age.