Sodden summer blamed for record loss of butterflies

This summer's wet weather is being blamed for the steep decline in the number of butterflies

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by Ruth Brooker

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With torrential downpours from April to August, 2012’s summer season has been the wettest for a century. But it’s not just our holiday plans that have been destroyed; the cold, wet weather is also being blamed for a marked decline in the number of British butterflies.

Long spells of soggy conditions prevent caterpillars from thriving and stop adults from finding mates and laying eggs for the next generation. Most butterflies need sunshine and balmy temperatures to gain enough energy to fly.

This year, the Butterfly Conservation launched their third Big Butterfly Count, which is the largest citizen science project in the world. People participating were asked to record online all the common species that they could spot during 15 minutes spent out in their garden or local park.

More than 25,000 people in the UK took part in the project, which counted 223,000 butterflies and day-flying moths. Sadly it discovered that 75% of species had declined in the last year. This is worse than the sodden summer of 2007, which indicates that there are fewer butterflies than ever in the British Isles and numbers have been declining since the 1970s.

Richard Fox, from Butterfly Conservation said: “we’re on track for one of the worst years on record for UK butterflies. Gardens were bereft of butterflies for much of the summer, robbing people of a quintessential sight of the season.”

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The number of peacock butterflies fell by 89% compared with 2011, but a late emergence of this butterfly in September’s sunnier weather may allow it to recover for next year. 

It was recorded that numbers of Common Blue butterflies fell by 50% and the Red Admiral, which was abundant last summer, fell by a dramatic 72%. All of the white butterflies declined, as did garden favourites such as the Holly Blue and Brimstone.

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This summer could bring extinctions of rare species such as the Heath Fritillary; because they are confined to just a few nature reserves, they are unable to escape poor weather conditions. This can cause them to become so small in number that they never fully recover.

However, a few species that love damp conditions have thrived. The Meadow Brown numbers were up by 186% compared to 2011, which makes it Britain’s most abundant species.

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The Ringlet and Marbled White also did well; Ringlet numbers increased by 354% and Marbled Whites rose by 503%. These species have caterpillars that feed on long grasses, so they may have benefitted from the lush growth of their food this year.

To help support butterfly populations, everyone who has a garden or even just a window box, can plant flowers such as lavender, buddleia and the perennial herb Marjoram, which feed butterflies.

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