Charlie has been overly protective of his sister April since she was returned to the Cherry Brook Zoo in April 2008. (CBC)The trauma of a younger sister being temporarily stolen seems to have had lasting effects on a monkey at the Cherry Brook Zoo.

Monkey thieves stole April on April 22, 2008, but apparently had a change of heart two days later. They left April in a small storage box behind a building in Saint John and an anonymous call led police to her.

April was returned to her family at the zoo and the story was thought to have had a happy ending.

But since then, April's older brother, Charlie, seems to have been deeply affected by the ordeal.

Charlie became overly protective of April after she was returned to the zoo.

And now, when any new baby monkey is born in the zoo, Charlie tries to keep them out of harm's way, as well.

The monkey holds onto them but the unintended consequence is that Charlie is not letting the babies get enough nourishment from the mother.

Charlie's overprotective tendencies have resulted in three baby monkeys dying since April was stolen.

Charlie, April to be moved

Lynda Collrin hopes a new baby will be born in the spring and survive after Charlie and April are separated. (CBC)Lynda Collrin, the director of zoo development at the Cherry Brook Zoo, said Charlie and April will be moved in the spring to avoid any future deaths.

"He's not taking them through aggression or not wanting babies there," Collrin said.

"He's taking them as a protector. And that's something that we have to break that cycle."

Collrin said the Cherry Brook Zoo hopes a new baby will be born, and survive, after the move takes place.

She said Charlie's reaction to the ordeal is a fascinating and unfortunate development of an otherwise happy story.

"We thought everything was OK," Collrin said.

"Time [has] shown us how fragile these animals are, and how easy it is to completely make a group dysfunctional."