DENVER – Denver Zoo’s Sumatran orangutan Nias is pregnant with her second baby, the zoo announced Thursday.

Zookeepers believe the baby will be born in March, based on changes in her body and when she was observed to be breeding with her new mate Berani.

Orangutan pregnancies, like human pregnancies, last around nine months.

If carried to term, this will be the fourth orangutan born at the Denver Zoo.

“Nias’ last pregnancy was successful, though it took a lot of effort to help Nias learn to breastfeed,” Denver Zoo associate veterinarian Gwen Jankowski said.

“We are monitoring her closely and are happy with what we see so far in this pregnancy.”

Nias’ first baby, a female named Hesty, was born in June 2010. She was the first orangutan birth at the Denver Zoo in 25 years.

The birth was normal, but the zoo said the weeks after were difficult because Nias didn’t know how to nurse the newborn.

Zoo staff bottle-fed the newborn and placed her in an incubator until both learned how to successfully nurse.

Zookeepers believe this second pregnancy and feeding will go smoother because Nias is an experienced mother.

Nias was born at the San Diego Zoo in July 1988 and came to the Denver Zoo in November 2005.

Berani was born at Florida’s Zoo Miami in February 1993 and arrived at the Denver Zoo from the Audubon Zoo in New Orleans in June.

The two were matched together under recommendation from the Association of Zoos and Aquariums’ Species Survival Plan.

Orangutan means “person of the forest” in the Malay language and the species is among the closest relatives to humans.

Physically, they are known for their stout bodies, long arms and shaggy, red hair.