Brown Argus on Bird's-foot-trefoil

Our last day surveying rail-side land started grey and damp, but by the afternoon the sun had appeared which brought out scores of bees and butterflies who were all making the most of the flower-rich grassland (see extra). 

My image is a Brown Argus, a species that was once rare in the UK and only lived on Common Rock-rose. This was probably because the plant tends to grow on south-facing slopes and absorbs the warmth and sun which the butterfly's caterpillars need. 


Climate change has benefited this species, with warmer temperatures encouraging the caterpillars to try other foodplants, notably Geranium species, especially Dove's-foot Crane's-bill. This has allowed them to move north at more than 2.3 times the average pace of other flourishing insect species, and they are now frequent around Peterborough, especially on brownfield land, and can be found as far north as Yorkshire..