Factors affecting the distribution of satyrid butterflies on arable farmland.
The effects of biotic and abiotic factors on the distribution of three species of nymphalids (Aphantopus hyperantus, Pyronia tithonus and Maniola jurtina) in arable field margins were studied in a block of arable farmland on a farm in northern Hampshire, UK. Non-floral factors affecting distribution included the degree of shelter, insolation, width of hedgebank or grass verge, and uncultivated habitat. Farm tracks adjacent to the field boundaries exerted a negative effect on abundance. Floral variables affecting distribution included the abundance of flowers of bramble (Rubus fruticosus), thistle-like Compositae, marjoram (Origanum vulgare) and mayweeds (Matricaria spp.) in conservation headlands. Negative variables included abundance of cow parsley (Anthriscus sylvestris) and old man's beard (Clematis vitalba); although the latter was negative for A. hyperantus and M. jurtina, it was a positive variable for P. tithonus. The distribution of butterflies in arable field margins is discussed in relation to landscape structure, microclimate and resources.