This paper examines the first appearance of butterflies using two sources, historical data from the former phenologieal reports of the Royal Meteorological Society and recent data from the extant Butterfly Monitoring Scheme Using regression techniques mean dates of appearance are related to Manley's central England temperatures and are then examined for other, unexplained, trends over time The observed relationships suggest that, in the absence of evolutionary change, climate warming of the order of 3°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 synchrony is likely to be maintained by a similar advance in timing The consequences of such changes to the phenology of British butterflies are discussed

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weather changes by analysing spring arrival of birds throughout Britain.

No abstract

Th e impact of climate change, in particular increasing spring temperatures, on life-cycle events of plants and animals has gained scientifi c attention in recent years. Leafi ng of trees , appearance and abundance of insects and migration of birds , across a range of species and countries, have been cited as phenotrends that are advancing in response to warmer spring temperatures. Th e ability of organisms to acclimate to variations in environmental conditions is known as phenotypic plasticity. Plasticity allows organisms to time developmental stages to coincide with optimum availability of environmental resources. Th ere may, however, come