A peek at rare monkeys safely hidden in a zoo

Three years ago a group of tiny, very rare primates came by accident to the Brookfield Zoo, near Chicago. The US government found 10 of the little animals, called Goeldi's marmosets, when smugglers tried to sneak them into the country illegally.

The government picked the Brookfield Zoo for their new home, and today half to one-third of the captive Goeldi's marmosets in the world are hidden there, according to the zoo's staff.

Keeping Goeldi's marmosets, also called "callimicos," is very difficult. So Don Anderson, the callimicos' original keeper, and Dr. Ben Beck, the zoo's curator of primates, wanted to learn everything they could about these animals before they arrived. They had less than two weeks to prepare for the Goeldi's.

"I gathered as much information as I could lay my hands on," Mr. Anderson says. As a result, he learned that one of the most important factors in the callimicos' survival was to have a very stable routine. He says, "Callimicos are very high-strung and flighty." They need an unchanging schedule to survive.

Only a few members of the zoo staff are allowed in to see them. The animals are sensitive to even small changes. "Even a new pair of shoes upsets them," says Dr. Beck. Their sharp senses help protect them from predators and help them search for food in their natural home in the Amazon River Basin of South America.

"If you can keep wild animals alive in the first seven months, you'll be likely to continue," Mr. Anderson says. So he spent 80 days in a row with the callimicos, from early morning until late at night. He wanted to keep special care of them because they are members of an endangered species and the only zoo callimicos in the United States.

These callimicos not only survived, but by now they have had babies. At first, the tiny baby callimico clings to its mother. After about four weeks, when the baby stops nursing, its father carries it around until it gets around by itself at about two months of age. Some of the callimicos born later were also partly cared for by older brothers and sisters.

The callimicos eat vegetables, live mealworms, crickets, lizards, earthworms, and newborn mice. Fruit is fed sparingly, partly because, the staff reports, "the animals are apt to fill up on juicy sweets."

The Goeldi's are housed in wood and wire mesh cages. The cages contain a wooden jungle gym designed by keeper Anderson.

Goeldi's are like other marmosets in a few ways but unlike them in others, so they are not considered to be true marmosets. Callimicos have fewer teeth than marmosets and give birth to one baby at a time (not twins).

Much of this information would not be known if the original 10 Goeldi's hadn't been taken in by Brookfield Zoo. Despite an enormous cost of money, time , and space, Goeldi's marmosets continue to be cared for and studied at the zoo.

"When their number reaches between 50 and 60, we'd like to give some to other zoos," says primate curator Beck.

Because of its work, the zoo has been given the Significant Achievement in Conservation Award by the American Association of Zoological Parks and Aquariums.