Kalista, a rare tiger species, has become the first-time mother of five cubs at the Saint Louis Zoo.
"It is so rare to have a litter of this size," said Steve Bircher, a curator of mammals at the zoo, in a public statement.
Although tiger litters usually comprise two to three cubs, as many as six have been recorded, according to the zoo.
Kalista, who certainly has her work cut out for her, has managed to nurse and care for all five of her cubs.
But zoo officials intervened when two of the three female cubs dropped weight and became fragile shortly after their births. Staff provided extra food and care but kept the cubs with their mother. The five weigh between 4.5 to 7 pounds each.
Kalista and her cubs will remain in a private indoor den until her little ones reach about three months of age. Their father, Khuntami, who was born in the wild and won't help rear his children, will stay on public display.
Amur (ah-MOOR') tigers, formerly called Siberian tigers, are part of a breeding program by the Association of Zoos and Aquariums, which estimates their captive numbers at 300.
Only about 500 of the rare species remain in the wild, inhabiting parts of eastern Russia and northeast China. These tigers are at risk because of habitat loss, human encroachment and poaching.