A young callimico monkey named April is missing from the Cherry Brook Zoo in Saint John after someone jumped a fence, kicked in a door and stole her from an enclosure.
Zoo director Len Collrin said it appears whoever took the small, black primate, also known as a Goeldi's monkey, knew what they were doing.
"They walked by a Golden Lion tamarin and went into the third enclosure, let the monkeys out and actually locked two back in," he said in an interview Wednesday. "One was still running around in the back hallway and last year's baby was missing."
Collrin said the monkey is 12-inches (0.3 metres) tall and weighs less than a pound (0.45 kilograms), adding that it's a high-maintenance animal that requires a special diet and won't make a good house pet.
"They are small animals, they are very fragile and they have a special diet," said Lynda Collrin, director of zoo development.
"We have to order in a canned food with a certain protein ratio, and we have to bring in a special high-protein monkey biscuit."
She said if someone feeds the monkey grapes and citrus fruits, the baby could go into insulin shock.
Collrin said the young monkey needs to be with its family.
"The whole family unit takes care of the baby, even the juvenile brother takes the baby and carries it," she said.
Collrin said the parents and brother are upset.
"They are either hiding ... or come up to the fence and are doing a distress call."
It wasn't clear if more than one person was involved in the heist.
A hack saw was used to unsuccessfully cut through a padlock and a hasp, before the door to the monkey's enclosure was kicked in.