They kill their own parents, children and neighbours. Now life is even worse for the vicious alpine marmot

The climate crisis has intensified the rodents' bloodthirsty fighting. From a chalet high on the French-Italian border, scientists are documenting their battles

The ecologist Christophe Bonenfant strides down the mountainside, a metal cage strapped to his back. Inside, a hessian bag twitches and squirms. His cargo is 4kg of befuddled alpine marmot, a mountain rodent admired by hikers, immortalised by Goethe and Beethoven, and the star of a beloved French ad for Milka chocolate.

The creatures' cuddly reputation, however, belies a vicious reality. The life of an alpine marmot is a never-ending bloody battle for dominance. They are, Bonenfant's colleague Rebecca Garcia says, mega-violent". And now the climate crisis is making their fight for survival in the Alps more deadly than ever.