Did you know male gorillas can eat up to 30 kg of vegetation every day?
Both of the two species are critically endangered (IUCN red list) and classify in the Appendix 1 of the CITES, as their populations are still decreasing and threatened by the illegal trade. The three main threats they are facing is poaching, diseases and habitat destruction (and human civil unrest for the eastern gorilla).
Mating and births occur throughout the year. The pregnancy lasts on average 9 months and usually, gorillas give birth to one child (Twin births occur approximately as often as in humans).
Because of their stature and strength, gorillas are often considered dangerous and brutal animals. However, gorillas are hardly ever violent; for the most part they are peaceful. A gorilla that thinks he or his family is in danger will first make threats, called "displays" (the most known being chest-beating), to intimidate.
Male gorillas can eat up to 30 kg of vegetation per day, with females eating 18 kg. They spend more than 50 % of their time feeding and foraging.
Gorillas are forest gardeners, meaning they have a crucial role in germination and propagation of plants in the forest. As herbivores who feed on fruit and plants, seeds that pass through their system during digestion can germinate once excreted. Some species of plants could not flourish without them.
Gorillas are neophobic animals. They are very sensitive to changes and especially to changes in their environment. It is why any changes in their habitat impact them a lot.
Every evening gorillas build a nest to sleep in, using the vegetation (they pull, layer and anchor branches to make the nest rim and they put leaves in the centre to be comfortable). Commonly they sleep in the trees, but they can also sleep on the ground (silverbacks sleep on the ground more often than females). Each animal builds their own nest, except infants who sleep with their mother.
Gorillas are the largest primate. Males are taller and bigger than females, and grow silver hair on their back during puberty (at about 15 years), caused by an increase in testosterone.
There are two gorilla species: western gorillas and eastern gorillas. Each one is divided in two sub-species: the Western Lowland gorilla living in west Africa, the Cross River gorilla living at the Nigerian/Cameroonian border; the Mountain gorilla living on the Virunga Volcanoes and in the Bwindi Forest and the Eastern Lowland gorilla living in the eastern Democratic Republic of Congo.
The social structure of gorilla is the harem. A group counts one male (called "Silverback"), several females and their offspring. When they reach their sexual maturity, males and females leave their natal group. The males usually spend a period alone before they form their own group. The females however join directly to another group or to a lone male.