In a tragic development in the theft of two highly endangered monkeys from Brisbane's Alma Park Zoo, the male of the pair has been found dead in the backyard of a house near the zoo.

Two cotton-top tamarins were stolen from the zoo Saturday night in what appeared to be a pre-meditated break-in.

Manager Gary Connell said the owner of the property phoned Alma Park to report their dog had found a strange looking animal in their yard.

"We went across with the curator and it was our male tamarin, unfortunately it was dead, it had been dead for a little while," he said.

"We're not convinced the dog has killed it, but the dog has actually found it and highlighted it to the owners.

"It's obvious that the male has been grabbed by whoever tried to take him, he had big bald patches on the back of him.

"Whoever tried to catch him him hasn't been aware of how to handle primates, pulled out a lot of his fur, and I say that could have been what caused the death."

Female pregnant

The female tamarin, Conchetta, is heavily pregnant and Mr Cole says it is likely she will miscarry due to the shock.

He is still holding out hope she will be returned alive, but warns she will not survive long outside of the zoo.

"Where the male was found wasn't that far from the zoo, it's a housing estate that has a public park between the zoo and the estate, so the male has obviously gone that way," he said.

"Whether the female has gone with him or whether she's been taken by the people who have broken in, we don't know."

Police have door-knocked the area in an attempt to look for more clues.

Mr Connell expressed his frustration at the callous act.

"I just find it very hard to understand why people would break into a zoo take such critically endangered animals - they're not a pet, there's no way you can treat them as a pet," he said.

"Sometimes I think people just don't have any commonsense anymore."

He is calling on whoever took the tamarins to return her to their local vet or RSPCA.

"All we're concerned about is the welfare of this female tamarin - please, you're not going to be able to keep it long-term as a pet," he said.

"The best thing you can do is get back to a vet or RSPCA, drop it in a box somewhere it can be secured and looked after.

"It's a really highly endangered animal and we plead with you to do the right thing."