“Our marmots aren't asleep yet, because of the mild temperatures at the moment,” zoo curator Tobias Rahde told press agency dpa.
In most years the marmots would have been in hibernation since mid-November.
Contacted by The Local, Rahde said that “if they don't sleep for one or two winters, it's not a problem, but more often can be dangerous.”
“If they're regularly not hibernating, we might take measures to help them, like creating a colder space and giving them less fatty food,” he said.
That would be the opposite of the steps the zoo currently takes to look after its animals used to warmer climates during the winter.
Okapi, for example, which are originally from Central Africa, are kept in a covered winter block with extra UV lighting to mimic sunlight, along with some tropical bird species.
Rahde said that there was little research available on the impact of warmer winters on marmots living in the wild, but “problems could slowly be developing”.
The animals, which are members of the squirrel family, mostly live in mountainous regions such as the Alps.