Louisville, Ky. (WHAS11) - The Louisville Zoo celebrated a special birthday this week.

On January 6, dozens of zoo guests sang “Happy Birthday” as Gorilla Helen dug into her custom fruit cake and special birthday enrichment items. It was a party zoo officials said fit Helen perfectly.

“Helen has always had a bit of an independent streak, and she has always worn a bit of a tiara in her own mind,” said Jane Anne Franklin, Supervisor of Animal Training and Mammal Curator at the Louisville Zoo.

Helen's 60 birthday

Helen's 60th birthday is especially significant as the median age of gorillas in a managed program of an Association of Zoos and Aquarium (AZA) facility is 38.3 years old. In the remnant wild, the average age is 35.

Franklin said, “There's some genetics that play into that, and we keep them moving. It's the old adage: use it or lose it. So, the environmental enrichment, the moving, the making sure that we take care of the subtleties we pick up on as they age has all helped quite a bit."

Helen is the third oldest known gorilla in the North American population. She is wild born, so her birth date is estimated.

Western lowland gorillas are considered critically endangered with an estimated 100,000 left in the remnant wild.

The birthday celebrations will take place in Gorilla Forest at noon.