An elderly squirrel monkey was stolen from the Magnetic Hill Zoo in Moncton as a prank, according to the general manager.

Hercules, 19, was taken from the monkey exhibit overnight Tuesday, but was returned safely Wednesday afternoon after zoo staff made a public appeal to get him back.

Bruce Dougan says he received an anonymous call from a man who thought he knew who had Hercules.

"It was some young men that were pulling a university prank just before going back to school, but they didn't really realize the trouble that they were really in having stolen or taken the squirrel monkey," Dougan told CBC News.

"He said if I was happy to get the squirrel monkey back, he would do what he could to get that back for me. But he would rather the police not get involved.

"And I was OK with that because my first priority was to get the squirrel monkey back here at the zoo safe and sound."

The Magnetic Hill Zoo has six squirrel monkeys. (Julie-Anne Lapointe/Radio-Canada)

Dougan met the man at a location outside the zoo and Hercules was returned in a cardboard box, no questions asked.

Hercules is currently under observation. He is very nervous and scared, said Dougan.

"He's probably had a pretty traumatic 16 or 18 hours. And so understandably he's a little out of sorts."

Hercules will be monitored in isolation for 24 hours before rejoining the other five squirrel monkeys, he said.

"I'm going to buy a lottery ticket on the way home," said Dougan. "This has been a very lucky day for us. We're very happy to have Hercules back, that's for sure."

Security under review

Meanwhile, officials are reviewing the zoo's security measures.

It's unclear how the theft occurred because the 40-acre zoo has security, including a dog, said Dougan.

The lock on the caged monkey exhibit was found cut Wednesday at 8 a.m. during a routine check by security.

"We're going to be reviewing all of our security procedures here and try and tighten them up," he said.

The zoo has six squirrel monkeys, including Sheldon, who made headlines last year as the orphaned monkey who had to be rushed to the Atlantic Veterinary College in Charlottetown when his mother died the day after he was born.

Hercules is the patriarch of the group and his age was of particular concern.

"It's a dangerous exotic animal. They do not make good pets and caring for an animal like that is extremely challenging, especially a geriatric squirrel monkey that does require specific care," said Jason Carson, the senior keeper of primates and monkeys.

"We're concerned about his physical well being and its health because these animals have a very specific diet and we're concerned about what kind of food and care this animal is going to be receiving now that he's not here," Dougan said earlier in the day.

"You know he's going to be very stressed because he's away from his troop, he's in unfamiliar surroundings with unfamiliar people and so we're very concerned about physiological well being as well."

Inexperienced people should not be handling these animals, Dougan had stressed.

"They can bite and any animal's mouth is full of bacteria, so there's always worry about infection and with very small children, they could probably give them a fairly serious bite."

Squirrel monkeys are the smallest of the primate family Cebidae and are typically found in the forests of southern North America and South America.

They usually weigh between one and 2.5 pounds and have an average lifespan of 15 to 25 years.

The zoo's website says they are threatened by habitat destruction, illegal hunting and capture for the pet trade or medical research.

In April 2008, a young Callimico goeldi monkey was stolen from the Cherry Brook Zoo in Saint John.

The nine-month-old South American marmoset named April was found a couple of days later after police received an anonymous tip. She was in a blue plastic box behind a building near a gas station in the Bayside Drive area.