"The bears are only young and love climbing the trees, but I've never seen one do a handstand at the top of a tree before," says Helmut Pechlaner, director of the Schoenbrunn Zoo in Vienna.
"Normally they slow down and sleep a lot at this time of year, but it has been so warm in Austria lately that they've been more active than usual."
Yang Yang and Long Hui are also under constant observation by zoo scientists as little is known about the habits of the Giant Panda.
It is hoped the two will mate and return to China as a family group but zoo keepers say that despite their best efforts the pandas are simply much more interested in bamboo than sex.
There are only an estimated 1,600 Giant Pandas left in the wild.