2 Koalas Stolen From Exhibit at S.F. Zoo

Two female koalas were reported stolen from the San Francisco Zoo on Wednesday, and officials said the stress could kill them within days if they do not receive proper care.

Leanne, 7, and her mother, Pat, 15, were discovered missing from their indoor quarters by an animal keeper. Zoo officials said someone apparently climbed onto the exhibit’s roof, broke through the skylight and entered the building through a furnace door. Police are investigating, but have no suspects yet.

Pat is an elderly koala and has several medical problems, including a potentially cancerous mass and an infected eyes.

She could be under added stress because koalas have a very specialized diet, eating only the freshest tips of eucalyptus buds, which are their main source of water.

“People in the horticulture department here have to go out daily to get them food,” said zoo spokeswoman Nancy Chan. “That’s why you don’t see them in zoos in this country. They don’t drink water. If someone had them, they wouldn’t know they don’t drink.”

The zoo’s seven koalas live in a building with a temperature kept at 65 to 70 degrees. They have no body fat, which makes them highly vulnerable to any changes in their environment.

“Any time you put them under any stress--moving them--you obviously tax the energy resources and they begin burning muscle,” said David Robinett, the zoo’s general curator. “The people who took these animals probably don’t know what it takes to take care of them. We would like to get them back any way, safely, that we possibly can.”

Zookeepers had reported suspicious activity in the area on Christmas, and the facility’s 24-hour security unit was put on alert. Robinett said he plans to evaluate the current security system and explore new methods of keeping animals safer without destroying the open habitats that many enjoy.

“We have security around the clock, but it’s a big zoo and covering it every minute of the day during the day or night is a lot of work,” he said. “I’m just hoping that whoever it is, they will hear this message and give us a call.”

Robinett said the koalas weighed about 12 to 16 pounds, and are known to claw and bite if threatened. He said zookeepers usually handle the animals with thick gloves or transport them in crates.

Koalas, native to Australia, are considered threatened. Chan said only about a dozen zoos in the United States have exhibits.