Tinga holds her two-month-old baby, Whimsie, and watches Jim, her partner and the dominant male in the group, walk away for a moment.

Visitors gather at the glass as the dominant male gorilla, Jim, walks by. Western lowland gorillas do climb but primarily spend their time on the ground.

Denver Zoo welcomed a rare addition on February 25: a western lowland gorilla named Whimsie Adepa (ah-deep-ah).

Western lowland gorilla populations have declined by more than 60 percent over the last 20 years due to poaching, according to the World Wildlife Fund.

Whimsie is the fifth of her species to ever be born at Denver Zoo, and the first in 11 years. Only 10 a year are born at zoos across the U.S., according to Denver zookeeper Michelle Valois.

Western lowland gorillas live in heavy rainforests in communities of up to 30. They have distinct social dynamics. There is one dominant older male, also called the silverback for his swath of silver hair. Communities include several females and babies, and sometimes a few other young males who then go off to find a community of their own.

Much like a human mother, Tinga pats Whimsie’s back and jiggles or changes positions to comfort her.

Denver Zoo has a troop of six gorillas: 11-year-old mother Tinga, 29-year-old father Jim, baby Whimsie, 39-year-old female Bossa, and “the bachelors,” 19-year-old Charlie and 20-year-old Curtis.

Tinga was born at Denver Zoo. Valois had just returned from maternity leave when Tinga was born and felt a very special connection with her. At age 2, Tinga moved to the Los Angeles Zoo and returned in November 2014 to be paired with Jim. “I was so happy when she came back. She returned incredibly intelligent and has formed a special bond with Jim,” she says. Whimsie is Tinga’s first baby.

Instinct is a lot of the game. Tinga is learning quickly how to be a mom. —Michelle Valois, zookeeper

“She’s very much a first-time mom,” Valois says. “She’s very protective and gentle.” A few days after the birth, zookeepers were concerned Whimsie was growing weak because she was not nursing. They trained Tinga to let them check Whimsie’s health and discovered the baby is actually very strong, according to Valois.

Whimsie is now nursing and Tinga is learning quickly how to be a mom. She pats Whimsie and jiggles or shakes positions to soothe her when she cries, which is often. Jim has not yet interacted with Whimsie, but is very protective over her and Tinga, pushing away other gorillas if she needs space.

Baby gorillas stick with their moms until they start to walk around at 6–9 months. At that point, zookeepers hope Jim will interact with Whimsie and they’ll begin to play together. Denver Zoo expects big crowds at that time. For more information, visit denverzoo.org