NASHVILLE, Tenn. (AP) — On closer examination, a rare clouded leopard born at the Nashville Zoo in March is actually a female, not a male as originally thought.

Zoo officials say the discovery was made after keepers noticed the cub wasn't developing at the same pace as a male clouded leopard of the same age.

Officials say the female cub is the first clouded leopard conceived through artificial insemination with frozen sperm.

In explaining the mix-up, they say it can be difficult to determine the gender of most species of newborn cats.

Officials say the discovery is actually a happy surprise because there are fewer young females than males in the clouded leopard species survival plan.

Clouded leopards are among the rarest of the world's cat species and have proved difficult to breed in captivity.