[font face=Serif][font size=5]Gourmet butterflies speed north[/font]

Posted on 24 May 2012

[font size=4]A new study led by scientists in the Department of Biology at the University of York has shown how a butterfly has changed its diet, and consequently has sped northwards in response to climate change. [/font]

[font size=3]Their study is published in the latest issue of Science.

The researchers found that warmer summers have allowed the Brown Argus butterfly to complete its life cycle by eating wild Geranium plants. Because the Geraniums are widespread in the British countryside, this change in diet has allowed the butterfly to expand its range in Britain at a surprisingly rapid rate. Over the past 20 years, the Brown Argus has spread northwards by around 79 kilometres and has become common in the countryside in much of southern England.

Lead author PhD student Rachel Pateman, of the University of York’s Department of Biology and the NERC Centre for Ecology & Hydrology, said: “Many species are shifting their distributions northwards as the climate warms, but this previously scarce species has surprised everyone by moving its range at over twice the average rate.”

Co-author Chris Thomas, Professor of Conservation Biology at York, said: “Because wild Geraniums are widespread in the landscape, the butterflies can now move from one patch of host plants to next and hence move rapidly through the landscape – expanding their range generation after generation.”

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