THE EFFECT OF SPRING TEMPERATURE ON THE APPEARANCE DATES OF BRITISH BUTTERFLIES 1883-1993

This paper examines the first appearance of butterflies using two sour ces; historical data from the former phenological reports of the Royal Meteorological Society and recent data from the extant Butterfly Moni toring Scheme. Using regression techniques mean dates of appearance ar e related to Manley's central England temperatures and are then examin ed for other, unexplained, trends over time. The observed relationship s suggest that, in the absence of evolutionary change, climate warming of the order of 3 degrees C could advance butterfly appearance by two to three weeks. The flowering of two of the larval foodplants of the orange tip butterfly is also examined, with the conclusion that synchr ony is likely to be maintained by a similar advance in timing. The con sequences of such changes to the phenology of British butterflies are discussed.