A major scientific report from Butterfly Conservation and the Centre for Ecology and Hydrology shows that almost three quarters of butterfly species in the UK have suffered population declines over the last 10 years. The State of the UK’s Butterflies 2011 report uses data collected by thousands of volunteers and mambers of the public to show that 72% of butterflies have declined in numbers in the first decade of the 21st century, while 54% have decreased their range in the UK.
It is not just the scarce, habitat specialists which have suffered. Even the common butterflies found in gardens and the wider countryside are becoming less common than they were. The Small Tortoiseshell, a favourite garden butterfly (see photo above by John Archer), has declined by 64%, partly due to the parasitic fly Sturmia bella, which has recently colonised the UK. But other common species, including Small and Large Skippers, Common Blue and Peacock, have all declined too, and habitat loss seems to be the main reason.
The report does have some good news. Introduced populations of the previously-extinct Large Blue are now thriving in Somerset, and the Heath Fritillary has been brought back from the brink of extinction by targeted conservation work in Kent and Devon. The Silver-washed Fritillary is another species which has expanded its range. We’ve seen evidence of this locally, as this spectacular buterfly has colonised Tower Hamlets Cemetery Park in the last couple of years. Several common butterfly species are expanding north, presumably due to climate change.
You can download the report here (PDF 3.5MB)