GREENVILLE, Wis. -- Police in Wisconsin are searching for the thieves who stole five baby animals from a zoo, including a kangaroo taken right from its mother's pouch.Workers at the Special Memories Zoo in Greenville say the four goats and the baby 'roo, called a 'joey', were taken Wednesday.The babies were bottle fed Tuesday night, but when workers went to the shed around midday Wednesday to start moving animals to the zoo in anticipation of Thursday's opening day, the five baby animals were gone, zoo owner Donna Wheeler told ABC News. She said the facility was not locked.Keepers are concerned for the animals' health.The condition of the kangaroo is a major concern. The joey needs to spend the first year with its mother or it will die."I believe the baby kangaroo is dead," Wheeler said. "It cannot live without its mother, it cannot live without special formula, it cannot live without heat."The head caretaker at the zoo discovered the caper when the goats were not in their pen and the joey was missing when crews arrived to move the animals from their winter enclosure.According to the Outagamie County Sheriff's Department, which responded to the stolen animals report, the joey was just 5 months old."I feel absolutely horrible. We do everything in our power to keep animals alive," zoo owner Donna Wheeler said. "Right now my stomach is just turning to think somebody would do that."So far, investigators don't have any leads and the zoo says there were no signs of forced entry.