Wall

Another long, almost hot, day of fieldwork at Whitemoor railway sidings. I took Rosie out for an hour's walk before we left, and then walked around for the best part of eight hours while we were out - not surprisingly I feel quite shattered.

This brownfield site is developing into a superb area for wildlife. There are many scarce plant species present in the short and sparse grassland that has developed over nutrient-poor substrates, and the varied range of habitats support a diverse invertebrate fauna, with many Breckland specialists. The ponds have breeding great crested newts, and the birdlife includes breeding kingfisher and , rather surprisingly, oystercatcher.

Today there were plenty of butterflies around, including common blues, grizzled skipper, brown argus and small copper. But I had to blip this image (heavily cropped) of a Wall butterfly Lasiomatta megera. In Cambridgeshire this formerly common species is now largely restricted to brownfield sites. It's a fast flying butterfly, that's easily spooked, and although I've seen a number flying at various sites, this is the first I've managed to photograph. I've reproduced some information about this species below.

The Wall gets its name from the characteristic behaviour of resting with wings two-thirds open on any bare surface, including bare ground and, of course, walls! Many people will have come across this butterfly on footpaths, especially in coastal areas, where the butterfly flies up when disturbed, before setting again a few metres ahead.

The basking behaviour of this butterfly allows it to benefit from the full warmth of the sun whose rays shine directly on the butterfly, but also get reflected back onto the butterfly from whichever surface it is resting on. This habit allows the butterfly to raise its body temperature sufficiently high for it to fly. In particularly hot weather, however, such basking is avoided and the butterfly may even retreat to a suitably-shaded spot to avoid overheating.

This species was once found throughout England, Wales, Ireland and parts of Scotland. Today, however, is a very different picture, with this species suffering severe declines over the last several decades. It is now confined to primarily coastal regions and has been lost from many sites in central, eastern and south-east England. In Scotland it is confined to coastal areas in the south-west of the country. It is also found on the Isle of Man and Channel Islands. This butterfly is found in relatively small colonies that are self-contained although some individuals will wander, allowing the species to quickly colonise suitable nearby sites.