Spotlight on Cheshire butterflies: the Small Heath (Coenonympha pamphilus)

In view of the present status of the Small Heath in Cheshire it seems amazing that not so many years ago it was still considered to be “generally distributed and common, probably everywhere, except in the immediate neighbourhood of large towns” (Mansbridge, 1940).

Due to a lack of recording work throughout much of the intervening period it is difficult to pinpoint exactly when and why the subsequent decline occurred. Some clues can, however, be drawn from its present distribution in the county where most colonies are now confined to coastal localities on the Wirral and in the Pennine foothills. In recent years the greatest losses have quite clearly occurred in the intensively farmed areas of the Cheshire Plain. Agricultural efficiency, with its overuse of herbicides and fertilisers, has created a virtual green desert in many lowland areas of the county. At these sites arable crops or “improved” grassland have replaced native grasses, which are the larval foodplant of the Small Heath.

Whilst modern agriculture can be blamed for many of the recent losses there are other contributory factors which need to be taken into consideration. Habitat destruction due to encroaching urbanisation and industrial developments have also caused losses at some sites, but even when these factors are taken into account it does not fully explain why the Small Heath is continuing to decline at many localities. Since the mid-1990s records show that further colonies have been lost at lowland sites where suitable habitat still exists – most notably at Delamere, Frodsham, Saltersley Moss, Styal, Rixton and Moore. The only stronghold now remaining in mid-Cheshire is on industrial wasteland around Northwich and even here numbers have declined sharply in the past few years. Most other records from the Cheshire Plain now refer to single sightings where individuals could either be wanderers from further afield or very small remnant populations.

Throughout most of Britain this butterfly remains widespread with the largest colonies found on dry habitats amongst short turf, although even at these sites local losses have occurred. It is possible that changing weather patterns are having an impact, but even that does not provide a satisfactory explanation as to why the problem appears more acute in Cheshire than most other counties.

This butterfly lives in self-contained colonies and in view of all the recording work undertaken in the last few years it would seem unlikely that in Cheshire many colonies remain undiscovered. The Small Heath is, however, an inconspicuous insect that always settles with its wings closed and could be missed by the casual observer. It is a double-brooded butterfly in this part of its range and has a variable flight period. The first emergence normally peaks in mid-June and the smaller second brood at anytime during July or August.

References:

Asher, J. et al. (2001). The Millennium Atlas of Butterflies in Britain and Ireland.

Mansbridge, W. (1940). The Lepidopterous Fauna of Lancashire and Cheshire.

Shaw, B.T. (1999). The Butterflies of Cheshire.

Written by Barry Shaw for News, the Cheshire and Peak Distrcit Branch of Butterfly Conservation magazine.