Common butterflies saw their numbers collapse over the summer despite the UK experiencing weather conditions that usually help them to thrive, results from the Big Butterfly Count have revealed.
The majority of butterfly species studied as part of the scheme saw their populations fall with some producing their worst numbers since the Big Butterfly Count scheme began.
Widespread species such as the Gatekeeper, Comma and Small Copper experienced their worst summers in the project’s history and were down 40%, 46% and 30% respectively compared to last year. The Small Tortoiseshell saw a 47% drop in numbers and Peacock slumped by 42% with both species recording their second worst years.
Numbers of the colourful Peacock have now dropped from an average of 3.6 individuals per count in 2013 to just 0.5 per Count in 2016, a 6-fold decrease over 3 years.
Participants also saw the lowest number of butterflies per count since the scheme began with an average of just 12 butterflies spotted.
These figures were even lower than those experienced during the cold and wet disaster summer of 2012 – the worst year on record for UK butterflies.
These falls come despite the summer of 2016 being warmer than average and relatively dry – conditions butterflies typically depend upon in order to successfully breed and feed.
Butterfly Conservation’s Head of Recording, Richard Fox, said:
“The drop in butterfly numbers this summer has been a shock and is a bit of a mystery. When we have cold, wet summers, as in 2012, we expect butterfly populations to plummet, but that wasn’t the case this year.
“The summer months were warmer than usual, yet most Big Butterfly Count participants saw fewer butterflies. Perhaps the very mild winter had a negative effect, or the cold spring, or perhaps the impacts of intensive farming and pesticides are really hitting these common species now.
“The importance of Big Butterfly Count is that it takes place every year over a long period; the longer it goes on the more we can learn about the causes that are driving the declines and in some cases, increases of our beautiful butterfly species. We are really grateful to the many thousands of people across the UK who do their bit to help butterflies by taking part in the Big Butterfly Count each summer.”
The Red Admiral and Green-veined White bucked the negative trend to experience good years. The Red Admiral was up 70% compared to 2015, had the largest year-on year-increase of any species and achieved its second highest abundance since the Count began. The Green-veined White was up by 58% compared to last year and was the only one of the common white butterfly species to experience a substantial rise in numbers.
The most commonly seen species was the Large White, up 2% from last year and topping the Count for the first time.
More than 36,000 people took part in this year’s Count, spotting around 390,000 butterflies during the 3-week mid-summer recording period. The Big Butterfly Count helps Butterfly Conservation find out how the UK’s common species are faring and how to best protect them in the future.
Results can be found at www.bigbutterflycount.org
Big Butterfly Count 2016 – top 10 species ranking
- Large White 62,890 seen
- Small White 61,955
- Meadow Brown 57,281
- Gatekeeper 47,597
- Ringlet 26,968
- Red Admiral 26,568
- Peacock 18,508
- Green-veined White 16,879
- Small Tortoiseshell 12,335
- Speckled Wood 10,271