BIRMINGHAM, Ala. (AP) — One of the two red pandas at an Alabama zoo has died, the zoo said Monday.

The Birmingham Zoo said in a news release that Parker, a 4-year-old male red panda, was found dead Sunday morning. There there was no sign of physical injuries or illness and an examination didn’t immediately reveal the cause of death, the zoo said, adding that more test results were pending.

There were no signs of illness in its other red panda, a 9-year-old female named Sorrel, the zoo said.

Red pandas, much smaller than black and white pandas, grow to about the size of large house cats, with long bushy tails. The International Union for Conservation of Nature and the World Wildlife Fund list the red panda, which is native to Asia, as an endangered species.