PHILADELPHIA (CBS) — The Gorilla family in Philadelphia is growing. Honi is pregnant.

Honi is a 21-year-old western lowland gorilla. She is one of five of her kind at the Philadelphia Zoo and she is pregnant. The proud papa is another zoo resident, 31-year-old Motuba.

READ MORE: Pennsylvania US Senate Race Between Republicans Mehmet Oz, Dave McCormick Too Close To Call

“We took Honi off contraception, and at the end of December we verified that they did breed,” said Kevin Murphy, General Curator of the Philadelphia Zoo. “We found out through a human pregnancy test that she was indeed pregnant and we verified it through an ultrasound. They were able to see a normal heartbeat and see a normal fetus.”

READ MORE: WATCH LIVE: PPA Joins Bicycle Coalition Of Greater Philadelphia To Announce Major Bike Lane Safety Initiative

This will be Honi’s second baby. She is mother to 13-year-old male gorilla, Kuchimba.

The baby is due in the fall. There is no word on the sex.

MORE NEWS: Parties Pick State Lawmakers To Be Lieutenant Gov Candidates

Murphy says this will be the first gorilla born at the zoo in 20 years, and the new addition will stay with mom for at least six years.