To those who inherited the wildlife conservation legacy of Steve Irwin, the law of the jungle comes naturally.

The law of man, however, has proved a little harder to negotiate. An animal hospital at Australia Zoo, which the late Irwin once operated, has broken the law 13 times by not releasing koalas back into the wild within their prescribed habitats, potentially endangering the marsupials.

Koalas released into foreign territory are considered to be at greater risk of disease or predators and, in the northeastern state of Queensland, must be placed no more than 5km (3 miles) from where they were found. But the hospital at the zoo, from which Irwin cut an international profile as a “wildlife warrior”, has repeatedly flouted the law, raising the ire of the state government.

“It is disappointing that an organisation held in such high regard has flouted regulations designed to protect the best interests of koalas,” Andrew McNamara, the state sustainability minister, said.

“The hospital has acknowledged breaches of the regulation, and senior management of Australia Zoo have assured the Environment Protection Association it won’t happen again.”

The breaches, which carry a maximum fine of A$12,375 (£5,700) each, come at an awkward time for the zoo, which is being sued for allegedly reneging on A$2.5 million in loans as part of a complex business restructuring.

There has also been intense speculation of a family rift between the crocodile hunter’s father, Bob, the founder of the zoo, and his widow, Terri, over the park’s increasing focus on commercialisation and the hectic career of her nine-year-old daughter Bindi.

Regional koala rescuers are no longer handing koalas into the zoo’s care after noticing that the animals were not returning. “Moving koalas is contrary to law and contrary to good scientific evidence,” David Horstman, of Pine Rivers Koala Care Association, said. “To me this is a long time in coming. Something really needed to be done.”

Jon Hanger, the director of veterinary services at the hospital, said that while they attempted to release koalas into their natural habitats, human intrusion into the wild meant that it was not always possible. He said that the hospital had demonstrated koalas’ ability to adjust to new environments through a tracking project run during the past year.

“These koalas were rescued from busy roads, which are not safe areas to return wildlife, or in the middle of urban developments, which put koalas at a big risk of further injury,” Dr Hanger said.

The zoo did not say where the koalas were released or whether they were still alive.

The Australian Koala Foundation says that although the animals have been listed as vulnerable since 2003 numbers have been dropping at an alarming rate and they are now endangered in southeast Queensland.

“It’s about 1,000 a year at least are euthanased automatically,” Deborah Tabart, the chief executive, said.

Sleepyhead

— The koala is a herbivorous marsupial and is not a bear

— Their average lifespan is 20 years. They can grow to 23-33cm (6085in) tall and can weigh up to 9kg (20lb)

— Koalas have opposable thumbs and fingers, which is rare for nonprimates. Their fingerprints are remarkably similar to those of humans

— Baby koalas, called joeys, are hairless, earless, blind and only a quarter of an inch long at birth. They then remain in the mother’s pouch for up to six months, feeding on milk

— Females reach maturity aged two or three years. A healthy female can produce one joey each year for 12 years

— Koalas sleep for up to 18 hours a day and eat almost nothing but eucalyptus leaves, up to a kilogram a day

— Koalas’ protection status is considered threatened, partly because of their shrinking habitat

Sources: National Geographic, University of Queensland, naturalscience.com

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