What is a silverback?
Apart from their size, the most striking characteristic of gorilla males is the so-called silverback. The silvery appearance is caused by short, white hair which covers the males' backs. In western gorillas, the silver colour extends to the upper thighs. Whereas the hair on their backs is shorter than in most other body parts, males have especially long hair on their arms. The silverback develops when the males are fully grown (usually at about 15 years of age in the wild). It is not a sign of old age.