According to the overview produced by Tourneur and Marchandeau (ONCFS, 1996) :

Bocage structures are evolving, rapidly in a trend towards simplification due to the destruction of a large numbers of hedges and earth banks, combined with changes in farming systems, which are becoming increasingly intensive and specialised. This hedge removal process depletes biological diversity as a result of :

 Disappearance of species that, at one stage or another in their development cycle, have make use of this uncultivated area, particularly species such as reptiles that depend on the existence of earth banks for their survival,
 Development of species well-suited to open fields (such as the starling), which can be considered "harmful" to insect-eating birds, for example, causing them to become scarce due to decreased availability of crop-dwelling insects.

Saint-Girons (1993) explains that "the main effect of the changes to the landscape currently taking place before our eyes is to decrease an area’s diversity, and more rarely its species richness, and to encourage invasive species.

Fortunately, a period of land consolidation marked by "hedge clearance on a massive scale" (Moinet, 1981) was followed by a collective realisation of the importance of bocage, as recorded by Hubaud (1992): "when considering land development projects, efforts were made to limit hedge removal. During the 1970’s, in the Morbihan department, an average of 110 to 120 m of hedgerow per hectare was uprooted (and more than 200 m in certain locations). The figure has now fallen to 22 to 25 m."

Preserving the quality of bocage terrain for wildlife implies maintaining diversity in hedges, in terms of both their structure and their botanical composition, as well as preserving adjacent structures, ensuring that field sizes are appropriate and maintaining an unbroken hedge network.