BOISE -- One of Zoo Boise's two endangered red panda cubs has died, the zoo announced Thursday.

The cub, named Whiskers, had stunted growth and was much smaller than the other male cub, according to the zoo.

Zoo officials say Whiskers likely had a weakened immune system, leaving him more susceptible to infection. Although the cub initially appeared to be thriving, staff at Zoo Boise noticed recently that he was acting lethargic.

Whiskers was removed from the exhibit for "intensive veterinary care," but ultimately died of a bacterial infection.

"We appreciate your support and condolences during this sad time," the zoo posted on their Facebook page.

Red pandas, which are native to the eastern Himalayas including China and Nepal, are considered an endangered species, with only about 10,000 left in the wild.