HOLIDAYS : Motherly Monkey Business : At the Los Angeles County Zoo nursery, chimps that have no parents are nurtured by humans.

Like most mothers, Michelle Sinton responds almost instantly when her infant cries out. She cuddles the child, sits in the rocking chair and begins humming a lullaby. It works just about every time.

There is one significant difference, however. Sinton’s babies are not human. They are primates.

“As everyone knows, primates are social, human-like creatures,” said Sinton, a Los Angeles County Zoo keeper who specializes in infant care at the zoo’s nursery in the Adventure Island section. “If they don’t have a mother, they use me like one. They have to have a personal connection in order to survive. So I become their security blanket.”

Since Sinton began working in the nursery almost five years ago, she has seen newborn primates come and go. Like the other zookeepers, Sinton, in effect, becomes a foster parent--bonding, feeding, rocking, grooming and playing with primates until they are mature enough to integrate back with their adult population. The process can take from several months to a year, depending on the species.

“This type of work is a real challenge,” said Sinton. “Every day is different, just like a mother’s. It’s never a dull moment.”

Sometimes the moments don’t come easy.

Last November, Sinton traveled to the Detroit Zoo, escorting two chimpanzees that she had practically raised since birth.

“Saying goodby was tough,” said Sinton. “But the zoo was able to keep the chimps together and that’s important. I stayed for several days and assisted with their adjustment. They have a wonderful exhibit there, and it helps to know what their new home looks like.”

At the Los Angeles Zoo, there are two nurseries--one for primates and mammals and another for the hoofed animals such as Chinese waterdeer, duikers and pronghorn antelope.

The zoo nursery, established in 1965, is especially festive this time a year when it is decorated for the holidays.

“Babies are given care when the mother dies, or for one reason or another she abandons it or if there’s an extreme health risk with the infant,” said Michael Dees, 45, who has been the zoo’s curator of mammals for the past five years.

“If at all possible, we want primates to be with other primates, even if they’re not the same species. They need the companionship, and it facilitates their growth,” he said.

Raising physically and emotionally healthy babies is the key to successfully integrating them at a later point.

“All the zookeepers, from the nursery to the adult exhibits, are involved with the integration,” Dees said. “It’s a delicate procedure that begins slowly, sometimes for only an hour a day. If we really get lucky, there’ll be another baby already in the exhibit.

If that’s the case, they’ll usually form an immediate attachment to each other. Then the job’s practically done for you.”

Long after a primate has been accepted into its adult home, Sinton says the bond between nursery keeper and animal remains.

“You can see it in their eyes,” she said. “There’s that special look they give you, a gleam of recognition. It’s really magical.”

Sometimes, as Sinton rocks an infant, she gets another treat--a human mother’s explanation to her own child about what Sinton’s doing.

“They say, ‘Look how tender she is with them. She’s cuddling them and caring for them because their mommy can’t do it for them right now. She gives them so much love and attention.’ I watch out of the corner of my eye as they watch me. What an experience!” she said.

The feeling is mutual.

“It’s my grandchildren’s favorite exhibit,” said Phyllis Shepard of Los Angeles. “It captivates us so that usually we experience it together without many words. But later, the kids always want to talk about what they were like as newborns. It brings up lots of special memories.”

WHERE AND WHEN

What: The infant nursery at the Los Angeles County Zoo is part of the Adventure Island exhibit. Zookeepers decorate the nursery for the holidays.

Hours: 10 a.m. to 5 p.m. daily.

Price: $7 adults, $3 for 2- through 12-year-olds, under 2 free.

Call: (213) 666-4650.