FACTORS AFFECTING THE ABUNDANCE OF BUTTERFLIES IN-FIELD BOUNDARIES INSWAVESEY FENS, CAMBRIDGESHIRE, UK

Surveys of the butterfly populations of a large number of field bounda ry transects were carried out in 1986 and 1991. The abundance of indiv idual species, total abundance and species richness were related to ch aracteristics of the field boundary and to field boundary flora using regression techniques Butterfly populations were enhanced in those bou ndaries containing large hedgerows, grassy areas in the form of verges or ditch banks, and where floral species richness was greatest. These features are more usually associated with the edges of pasture fields . A small set of additional data suggested the detrimental effect of a grochemical applications to butterflies. The importance of field bound aries in providing a network for movement between habitat patches is d iscussed