other between each bout. Gestation lasts about 131 days. Prior to giving birth, the female selects a denning site, such as a tree, log or stump hollow or rock crevice, and builds a nest using material from nearby, such as twigs, sticks, branches, bark bits, leaves, grass and moss. Litters typically consist of one to four cubs that are born fully furred but blind. They are entirely dependent on their mother for the first three to four months until they first leave the nest. They nurse for their first five months. The bond between mother and offspring lasts until the next mating season. Cubs are fully grown at around 12 months and at around 18 months they reach sexual maturity. Two radio-collared cubs in eastern Nepal separated from their mothers at the age of 7–8 months and left their birth areas three weeks later. They reached new home ranges within 26–42 days and became residents after exploring them for 42–44 days. Mortality and diseases The red panda's lifespan in captivity reaches 14 years. They have been recorded falling prey to leopards in the wild. Faecal samples of red panda collected in Nepal contained parasitic protozoa, amoebozoans, roundworms, trematodes and tapeworms. Roundworms, tapeworms and coccidia were also found in red panda scat collected in Rara and Langtang National Parks. Fourteen red pandas at the Knoxville Zoo suffered from severe ringworm, so the tails of two were amputated. Chagas disease was reported as the cause of death of a red panda kept in a Kansas zoo. Amdoparvovirus was detected in the scat of six red pandas in the Sacramento Zoo. Eight captive red pandas in a Chinese zoo suffered from shortness of breath and fever shortly before they died of pneumonia; autopsy revealed that they had antibodies to the protozoans Toxoplasma gondii and Sarcocystis species indicating that they were intermediate hosts. A captive red panda in the Chengdu Research Base of Giant Panda Breeding died of unknown reasons; an autopsy showed that its kidneys, liver and lungs were damaged by a bacterial infection caused by Escherichia coli. Threats The red panda is primarily threatened by the destruction and fragmentation of its habitat, the causes of which include increasing human population, deforestation, the unlawful taking of non-wood forest material and disturbances by herders and livestock. Trampling by livestock inhibits bamboo growth, and clearcutting decreases the ability of some bamboo species to regenerate. The