( CNN ) -- Everyone fantasizes about breaking free from life 's constraints , but a curious koala at the San Diego Zoo lived the dream Tuesday . Mundu , a 2-year-old koala , escaped from his enclosure , spending the day sleeping in a tree high above his exhibit . Zookeepers discovered he was missing shortly after feeding and watering the koalas at about 9 a.m. PT , said Jenny Mehlow , a zoo spokeswoman . No one knows exactly how he got out . But Mundu is on the cusp of sexual maturity , Mehlow said . His hormones are raging and he is constantly testing limits . Because the koala was not in any danger and did not pose any risk to the public , zookeepers took shifts watching Mundu in the tree . When the zoo closed , they lured him back into his exhibit . Mundu was then checked by a veterinarian . According to the San Diego Zoo website , the facility is famous for having the largest koala colony and the most successful breeding program outside of Australia . The exhibit has a Koala Cam , but Mundu 's Houdini-like move was not caught on camera . Leopard on the loose in Indian city . Zoo CSI shows how red panda may have escaped . 10 weirdest zoo animal escapes .
NEW : Mundu , a 2-year-old koala , is back and being checked out by a veterinarian . He spent the day sleeping in a tree high above his exhibit . No one knows exactly how he got out , but he posed no danger to the public . The zoo has been closed since Monday because of an outbreak of dengue fever that began at the San Diego Zoo Safari Park on June 1.