An endangered gorilla is pregnant at the National Zoo in D.C.

Calaya, a 20-year-old western lowland gorilla, is pregnant at the National Zoo in Washington. She's also mother to Moke, a 4-year-old male gorilla. (Smithsonian’s National Zoo and Conservation Biology Institute)

An endangered gorilla is pregnant at the National Zoo in Washington, and keepers are ecstatic.

Calaya, a 20-year-old western lowland gorilla, is expecting her second baby gorilla between late May and early July. Experts said she and 30-year-old Baraka, a male silverback western lowland gorilla, successfully mated in September. The next month, a pregnancy test — like the ones used for humans — showed she was positive.

“We’re absolutely excited about it,” Becky Malinsky, the primate curator at the Smithsonian’s National Zoo and Conservation Biology Institute, said in an interview Monday. “Gorillas in the wild are critically endangered, so every birth is incredibly important, whether in the wild or in human care.”

❤️🦍 Get ready for a #GorillaStory sequel—Moke is going to be a big brother! Here, he's looking over mom Calaya's shoulder as she voluntarily participates in an ultrasound. Baby no. 2—a boon to this critically endangered species—is due in a few months! >>https://t.co/e28cOkT7hM. pic.twitter.com/g6ylKmKnFc

— National Zoo (@NationalZoo) March 23, 2023

For the parents, it will be their second offspring. They had Moke, a male, in April 2018. Zookeepers report Moke is doing well and is “a handful,” according to Malinsky. “He’s rambunctious and full of energy,” she said of the gorilla, soon to be 5 years old.

Experts at the zoo followed a species survival and breeding plan from the Association of Zoos and Aquariums for Baraka and Calaya. The specialists determine which animals to breed based on their “genetic makeup, health and temperament,” according to a statement from the zoo.

Calaya is protective and cautious, zookeepers said in the statement, and they expect she’ll again prove to be a good mother. Baraka has a “relaxed and playful personality” and has been “very tolerant” of Moke’s playfulness. Keepers will watch to see how Moke reacts to being a big brother.

Gorillas live in groups called troops. There’s often a silverback male, one or more other males and females, plus offspring. At the National Zoo, there’s Moke, his parents and two other females — Mandara, 40, and her daughter, Kibibi, 14.

In the wild, western lowland gorillas are critically endangered because of poaching, habitat loss and disease. They’re native to Africa and live in forests. In the last two decades, experts said, the number of western lowland gorillas in the wild has dropped by 60 percent.

Malinsky said Calaya is doing fine in her pregnancy so far. At times, she shows she’s “not feeling 100 percent” by sleeping a little later or rejecting certain foods. But Malinsky said it’s all similar behavior to when Calaya was pregnant with Moke. Keepers said they have a 13-page birthing plan for Calaya that covers subjects such as her medical history, what signs to look for when she goes into labor and delivery of the baby gorilla.

Ultrasounds show the gorilla fetus looks healthy and is “very active,” according to Malinsky.

“Our vets keep saying it’s a big baby,” she said.