The idea of managing nature appears in the early 80s and replaces the previous principle of noninterventionist environmental protection. It is characterized by the use of extensive pastures as a means of managing the protected zones. At the ethnology/agronomy interface, the empirical survey conducted in the nature reserve of Bruges in the Gironde bears on the choice of a local or archaic cattle that would graze in the protected area. The project of ecology experts to make this cattle revert to their wild state was stopped by the status defining them as « domestic » animals. Reserve managers then had to acquire an expertise of cattle breeders. These new relations between ecological and agricultural knowledge led to a new form of extensive cattle breeding : « eco-breeding ».