Young red pandas attain adult size at 12 months and are sexually mature by 18 months.
All known births occur between 1600 and 0900 h, the period of highest activity. Parturition occurs rapidly, with females quickly cleaning the cubs and remaining with them for 60-90% of the time during the first few days after birth. For the first 7 to 10 days after birth, young remain essentially immobile, except when nursing. The mother remains curled around them, when in the nest, and, in her absence, the young sleep in a curled or semi-curled position, often in contact with one another.
After the cubs are about 1 week old, the females gradually spend more time away from them, returning every few hours to nurse and groom them. Gradually, the young become more active and move about in an uncoordinated fashion. They are able to right themselves when placed on their back by day 12. By day 18, the eyes are open and the young are able to orient toward light. By day 60, siblings are engaging in rough and tumble play in the nest and frequently venture to the entrance.
Young are nest-bound for approximately 90 days, after which, they make their first excursions from the nest at night. They are able to climb proficiently by this time. At first, mothers attempt to restrain cubs from emerging, but cubs soon become too active to monitor closely. Initial excursions from the nest coincide with the first evidence of the young eating solid food.
By 120 days of age, young consistently rest away from the nest area with their mother. Mother-young proximity continues to be close until the onset of the next breading season when mild aggression between the mother and young may occur.
Young red pandas attain adult size at approximately 12 months and are sexually mature at approximately 18 months.