The relative effects of woodland management and pheasant Phasianus colchicus predation on the survival of the pearl- bordered and small pearl-bordered fritillaries Boloria euphrosyne and B. selene in the south of England.

Abstract

Many British species of woodland butterfly have declined in recent decades. Different hypotheses have been proposed to account for this including changes in woodland management or an increased rate of larval/pupal predation by pheasants Phasianus colchicus resulting from the large-scale release of reared birds to supplement autumn numbers for shooting. We examined the effects of exposure to foraging pheasants on the rate of loss of larval pearl-bordered fritillaries Boloria euphrosyne. We also compared recent rates of colony loss of this species and the small pearl-bordered fritillary B. selene in woods with and without pheasant releasing. We found no evidence to support the hypothesis that pheasant predation led to significantly raised rates of larval loss, or that butterfly colonies in woods used for pheasant release had been more prone to extinction. Instead, surviving colonies of fritillaries were associated with the presence of active coppice management or young plantations on previously afforested sites.