Based on a 2001-2003 study of the involvement of hunters in the political movement Hunting, Fishing, Nature and Traditions in the Bay of Somme this article describes the reactions of hunters to the transformations of their familiar natural environment. It shows how nature protection policies interfere with the cynegetical construction of nature and turn ordinary practices into political experiences. This emphasizes the social character of the conflictual antagonistic conceptions of nature : whether these policies mobilize the most objective science or the most experienced commonsense, they aim at a social appropriation of natural spaces by defining their legitimate social uses.