Moka, 22, gave birth to her second son, Frankie, last May while on exhibit. The zoo said since many guests had the opportunity to witness his birth, they wanted to share his birthday with all of the visitors.
Sunday's celebration included streamers and wrapped birthday presents with Frankie's favorite things, including peanuts and vegetables.
The zoo said Frankie is an ambassador for western lowland gorillas in the wild. They are currently listed as critically endangered, as their population is rapidly decreasing.