A 59-year-old Austrian zookeeper has been sacked after planting and cultivating up to 30 marijuana plants in a rhinoceros' cage over an eight year period.
The elaborate operation was discovered at the Hellbrunn Zoo near Salzburg after a tip-off from one of the keepers' drug clients.
The man was the only human allowed in the enclosure, which allowed him to tend to his plants without suspicion.
The rhinos never ate the cannabis plants.
Salzburg Hellbrunn Zoo director Sabine Grebner said the employee was fired and the plants removed.
"It's horrible. We never thought such a thing was possible. We are here for families and kids and we don't have anything to do with drugs," she said.
The man also faces charges for illegally possessing weapons after officers found a gun and a shotgun in his flat.