Two giant panda cubs sleep in the nursery, each in its own temperature-controlled incubator. Although only a week apart in age, the 4-week-old cub (left) is much larger and has a fuller fur coat than the younger cub. The older cub was born to an experienced panda mother, known to produce high volumes of milk. The smaller cub’s mother is producing less milk. The Wolong staff knows to expect this potential problem. With so many pandas, they often collect milk from high-producing females, to supplement the twins in addition to the nursery formula.