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PITTSBURGH (KDKA) — It was a double celebration at the Pittsburgh Zoo on Sunday as they celebrated both World Gorilla Day and a milestone birthday for one of their Western lowland gorillas.

World Gorilla Day, sponsored by Go Ape USA, was celebrated from 11 a.m. to 2 p.m.

Zakula (Photo Credit: Pittsburgh Zoo & PPG Aquarium)

The Zoo was also celebrating Zakula’s 50th birthday. The average lifespan of a Western lowland gorilla in the wild is 35 years.

Zakula got her favorite treat, popcorn, and the Zoo says although she has to take medication for arthritis, she’s still able to keep up with the rest of the troop, including her two grandsons.

The Zoo says Zakula is the 7th oldest gorilla in North America and the 4th oldest female gorilla.

Zoo visitors also got to see the zoo’s newest gorilla, 4-month-old Frankie, who is learning to move around on his own and explore his environment.

Frankie (Photo Credit: Pittsburgh Zoo & PPG Aquarium)

Western lowland gorillas are critically endangered.