Joice and Bunny, two chimpanzees at the Maryland Zoo in Baltimore, are expecting, officials announced Wednesday morning.
It would mark the first chimps born at the zoo in six years and would increase the chimp count to 13.
"We are cautiously optimistic about having two successful chimpanzee births this year," said Mike McClure, the zoo's general curator. Both Joice and Bunny are healthy, McClure said, but they are under increased supervision because complications in giving birth are not rare.
The Maryland Zoo has 11 chimpanzees. Joice, 40, is the oldest and one of the original members of the Chimpanzee Forest, which opened in 1995.
She is a mother figure in the troop — aunt to Carole and mother to Renee, age 19, and Jambo, 6, the zoo's last successful chimp birth. It is not uncommon for chimps to stay fertile into their 40s, and it was expected Joice would breed again.
"She is a proven mother, and we are happy she is pregnant again," McClure said.
Bunny's pregnancy was more surprising. At 22, she is one of the least dominant females in the troop and is mostly deaf.
Chimpanzee gestation is about eight months. Bunny is expected to deliver sometime between now and May, and Joice in midsummer.
DNA tests will be run to determine which of the zoo's three male chimps fathered the babies, McClure said.