The tides of rain hit the butterfly breeding season, leaving many vulnerable species even more threatened, say experts from the charity Butterfly Conservation. By the end of the soggy season last year eight species were at an all-time low and and butterfly numbers in general were at their lowest in a quarter of a century.
If stocks are to recover from the onslaught of 2007, we need a warm few months ahead, says Dr Tom Brereton, head of monitoring at Butterfly Conservation, which studies the 59 native British butterfly species across 900 sites in the UK. Three-quarters of our species are in decline, and when a creature is already vulnerable, a dose of terrible weather can all but wipe it out.
Butterflies, which are happiest in habitats such as moorland, chalk grassland and ancient woodland, or around wild nectar-rich flowers and short grass, are unable to fly in heavy rain. Even if the weather is not particularly cold, rain lowers the temperature and makes them sluggish.
They sit on twigs or hid under ledges, and being stationary makes them more vulnerable to predators such as birds and spiders. The butterfly’s life cycle from egg to adult lasts about a year, with a mating season of only a week or two when they reach their adult state. Being unable to fly because of heavy downpours makes reproduction far less likely.
Compared to 2003, the Small Tortoiseshell butterfly population is down 81 per cent, the Common Blue is down 78 per cent, the Lulworth Skipper is down 73 per cent and the Small Skipper down 60 per cent. Other struggling species are the Chalkhill Blue, the Speckled Wood, the Grayling and the Wall Brown.
“The population of butterflies in the country hasn’t been helped over decades by intensification of agriculture and woodland management,” says Dr Brereton. “There’s been a loss of diverse habitat and fragmentation of habitat, which means butterflies can’t easily fly between different areas because they are so far apart.”
The High Brown Fritillary is now present at only about 50 sites across the UK, and the Duke of Burgundy is seen at about 100, considerably fewer than a decade ago.
Butterfly Conservation uses thousands of volunteers to monitor numbers each year, and the charity has now launched a new campaign and appeal called Stop Extinction.
Sir David Attenborough, president of Butterfly Conservation, is promoting the appeal to help raise funds aimed at improving habitats and raising awareness. “Butterflies face mounting threats, and some face possible extinction,” he says.
There’s not a lot we can do about the weather, including unseasonal downpours that batter the wings of delicate creatures. But how can we encourage butterflies to flourish in our gardens?
“Plant flowers and shrubs that either provide food for the caterpillar or nectar for the butterfly,” says Tom Brereton. “Ice plants, budleia, red valerian, thistles in general, and ivy are all great for butterflies. And I know it’s a bit untidy, but finding a corner to put in some nettles gives caterpillars great feed.
“A garden with butterflies flitting from flower to flower is beautiful, and also indicates a healthy environment with a wealth of wildlife.”
Butterflies like warmth so choose sunny, sheltered spots when planting nectar plants, says Dr Brereton.
Plant lots of different nectar plants to increase the number of species, and put the same types of plants together in blocks. Try to plant so there are flowers right through the butterfly season from spring to autumn.
Spring flowers are vital for butterflies coming out of hibernation. Autumn flowers help butterflies build up their reserves for winter. Plant original species as they provide much more nectar than hybrids.
Prolong flowering by deadheading flowers, mulching with organic compost, and watering well to keep the plants healthy. Plants that are well-watered will produce far more nectar for hungry butterflies.