Which European marmot can spend up to nine months per year in hibernation?

The European marmot that can spend up to nine months per year in hibernation is the Alpine marmot.

The Alpine marmot (Marmota marmota) lives in mountainous regions of central and southern Europe, including the Alps, Carpathians, Tatras and northern Apennines. It is adapted to long, cold winters and short alpine summers, so much of its annual rhythm is devoted to feeding and preparing for dormancy.

Before winter, Alpine marmots eat heavily and build fat reserves. They also collect dry plant stems to line their burrows, then seal the entrance with earth and faeces. Several animals huddle together underground, helping conserve body heat while their metabolism slows dramatically.

The species is sometimes confused with North American marmots such as the Olympic or yellow-bellied marmot. Those are different species with separate ranges. Alpine marmots are also notable for their Ice Age history: they originated in the Pleistocene cold steppe and later persisted in high mountain meadows after that habitat disappeared.