The Ptarmigan of Austria survive the harsh winter months by burrowing into snow just like Ruffed Grouse of North America. Their bird sized snow caves provide concealment from predators and maintain temperatures above 20°F.
These hidden winter shelters are super effective at hiding birds and this wouldn’t be the first time we have seen a bird get roused by a passing skier or snowboarder. In this instance the bird seems to have taken issue with the intrusion and for dive bombing mission on his head.