Are there no deer in France? Why are the wolves dining solely on shhep?
They like Fox.
There are deer in France, as well as boar, but sheep are easier pickings - there are more of them, for one, and they are a herd animal, so when a wolf has found them, he's found more than one, and can pick out the easiest target from a large selection. Also, imagine which would win a race, a sheep or a deer? Deer are wild, born so, and the attributes that keep them alive long enough to produce fawns are valuable genes - something that has been bred out of many domesticated animals, often because those same attributes that keep wild animals alive, are what make domesticated animals unruly, difficult to manage.
Easy prey.