Red pandas are excellent tree climbers; most active at dawn, dusk and at night foraging for food. Most of the day is spent resting in trees conserving energy, as their bamboo diet has a low energy content. Adults are normally solitary outside of the breeding season. At the onset of mating season a male and a female rest, move and eat in close proximity, as scent-marking the territory increases. A litter of usually 2 cubs is born in a nest in a hollow tree or rock crevice, and the young stay with their mother for about a year. Red pandas' vocal repertoire is small but varied (squeal, snort, grunt, etc.). They have a maximum lifespan of approximately 14 years.