THE BABY, who will probably be named Corey, is a tiny ball of white fluff clinging for dear life to its mother, Imogene, a black and white colobus monkey. The father, whose name is Ditto, watches from his perch on the family climbing equipment, passively tolerant.

"The male came from the Brookfield Zoo seven months ago," says head primate keeper Lisa Stevens. "The gestation period is five months, and the baby was a surprise. Colobus monkeys are shy, so you don't see them copulate. This is her second baby. Her first mate died the week after her daughter was born, and she raised the baby by herself."

Zoo officials aren't sure whether this baby, born October 10, is male or female.

"Once it gets off the mother, we'll get a good look," says Stevens. "The baby was born in the early morning, and the keepers discovered it when they came in. Primates are good mothers. She detached the placenta, and we removed it and checked it . . . She carries the baby all the time. She'll nurse it until she has another offspring, in about a year."

Colobus monkeys, which range in the wild from Ethiopia to Tanzania and Zaire, are black and white, but their infants are all white.

"Biologists believe that the fact that infants have different pelage has something to do with the group recognition of the infant state," explains Stevens. "Others often carry the babies and the white fur tells them it's an infant, so they'll give it special care."

Across the Monkey House aisle, a four- month-old colobus baby tentatively christened Oreo is already living up to its name, trading the all-white infant pellage for the black-and- white coat of its elders. Oreo's mother, Emily, and father, Emil, have a live-in babysitter, their daughter Eileen. In the wild, females often pitch in to take care of babies, a practice called "aunting."

"Eileen is very interested in grooming and taking care of the baby," says Stevens. "This is an important experience to prepare her to become a mother."

Meanwhile, on a bluff high above the water on Monkey Island, Muffin picks up her five- month-old daughter Puddin and cradles her protectively.

"She saw us coming and picked up the baby," says Stevens.

Puddin, Muffin and Puddin's father Pillsbury are Barbary Macaques, and Puddin was born May 27 on Monkey Island. She spends most of her time romping around the island and riding on her father's back.

"Macaques have a more actively fatherly role than other monkeys," says Stevens.

By contrast, Willy, the baby spectacled bear, sees his father only occasionally and briefly.

"We haven't pushed it," explains Associate Keeper of Mammals Daryl Bonness. "It's possible the male might kill the cub."

Spectacled bears come from South America and are cuddly-looking brown animals who get their names from the white patches that make circles around their eyes. Willy, named for veteran keeper William Rose, was born last January to Mimi.

"We locked Mimi in a cubbing den with some hay, and she lined the den," Bonness said. She was left undisturbed, monitored via video, for three months while the one-pound cub grew big enough to deal with the outside world. Now a roly-poly 60-pounder, Willy spends most of his time climbing on the play equipment in his hilly yard.

"Even in the cubbing den he climbed on the mesh doors," says Bonness.

Leon D'Oro and Farallon, the baby California sea lions cavorting around the pool, look like twins but aren't, quite. They have the same father, Norman, the only adult male in the sea lion pool, but their mothers are, respectively, Maureen and Pearl. A sea lion baby can't mistake its mother's distinctive bark.

Leon D'Oro, a male, and Farallon, a female, were born last June on the rocks around the pool. All teepers had to do was keep the pool filled. "They're capable of swimming at birth, but they're uncoordinated," Bonness said. "We make sure the water level is high enough so they can get out if they fall in."

The pups started swimming in the shallows at about three weeks. Now they're seasoned swimmers, diving off the rocks and swimming backwards underwater like the adults.

"There's the baby back there by the trees," says kangaroo keeper Lee Battle, but even as Battle speaks the joey is climbing back into its mother's pouch. The mother's name is Florence and the baby has no name as yet. Nobody knows its sex or exactly how old it is.

"Nobody can tell you the true birth," says Battle. "It started sticking its head out of the pouch about two months ago and it was probably in the pouch about a month before that. There are two more kangaroos with babies in their pouches now. You can just see a bulge."

A baby kangaroo, or joey, is about the size of a mouse at birth. The joey completes its develop within the pouch, nursing around the clock. Eventually, it sticks its head out. Even when it's big enough to leap around, it returns to the pouch to nurse. At the age of about four months, it joins the adult chow line for apples, carrots, greens and sweet potatoes.

By contrast, the baby zebra in the enclosure next door was walking within an hour after its birth in August. "She was born after hours," says Battle. "We were expecting it and we put hay in the stall, but she gave birth outdoors."

A zebra gives birth lying down, then licks off the baby and nuzzles it to see if it's normal. Then she stands up and, if the baby wants to nurse, it has to stand up, too.

Hippo babies nurse underwater, and the zoo has two baby hippos -- Tina, a pigmy hippo born in February to Epsilon and Totota, and Jones, a Nile hippo born in September to Arusha and Happy. For Arusha, who has apparently stopped pining away for her longtime mate, Joe Smith, who died last year, it was baby No. 19.

"It was a breech birth in shallow water," says keeper Morna Holden. "But she didn't need any help -- not after nineteen." NEW AT THE ZOO

In addition to the animals mentioned above, new additions at the zoo include: a red-footed tortoise, a leopard tortoise, and six Cuban crocodiles, all in the Reptile House; a hammerhead bat in the Lion House foyer; a two-toed sloth, a blacktailed tamarin, a guinea-piglike rock cavies and a Goeldi's marmoset, in the Small Mammal House; a red panda, opposite Monkey Island; a muntjac (tusked deer), five damas gazelles and a dorcas gazelle in the hoofed-stock area near the zebras.

The zoo grounds are open daily from 8 to 6, and the buildings are open from 10 to 4:30. Baby animals are most active in the morning. SUNDAY AFTERNOON AT THE ZOO

Animal babies aside, the zoo has plenty more to offer, especially on Sunday afternoons when special events are held from 1 to 3:30 in the Educational Building. All the following are free.

NOVEMBER 18 -- A celebration of animals with the U.S. Navy Brass Band Quintet, "The Archaesus Mimes" and zoo artists.

NOVEMBER 25 -- An update on the program "To Return the Golden Lion Tamarin to the Wild."

DECEMBER 2 -- Animal Folktales from many lands.

DECEMBER 9 -- "Super Lizard," a dancer demonstrates lizard movement and behavior.

DECEMBER 16 -- Tree-decorating party. Bring an edible ornament for birds and squirrels.

DECEMBER 23 -- Holiday Film Festival.

DECEMBER 30 -- Puppet show and workshop. Bring a 12-inch square of fabric.

JANUARY 6 -- Explore ways animals communicate.

JANUARY 13 -- "Animals in Animation."

JANUARY 20 -- An elephant dance by the Baltimore Dance Theater.

JANUARY 27 -- A program on zoos past and present.

FEBRUARY 3 -- A program with the Zoo's director.

FEBRUARY 10 -- Zoo Design. Learn what artitects must consider when they design zoos and animal houses.

FEBRUARY 17 -- Fictional and factual films about dinosaurs.

FEBRUARY 24 -- A workshop on African cloth paintings.

MARCH 3 -- Seal and sea lion demonstrations and films.

MARCH 10 -- Tips from the Zoo's photographer on photographing animals.