The curse of the UK summer holiday weather struck Big Butterfly Count 2017. For butterflies and butterfly counters, July and August were dominated by unsettled weather and above average rainfall. Overall it was one of the wettest UK summers for 100 years. And this after six months (January-June) of above average monthly temperatures, which encouraged butterflies to emerge earlier than usual.
The combined impacts of this topsy-turvy weather were to reduce the numbers of butterflies seen during Big Butterfly Count 2017, both because the abundance of some species was reduced by the summer weather and because others, such as the Large Skipper and Meadow Brown, had come out early and were already past their peak numbers when the count started. Consequently, an average of just 10.9 insects per count was recorded, down from 12.2 in 2016. Indeed the average number of individual butterflies per count has decreased in each year of big butterfly count since 2013, when over twice as many butterflies were seen per count compared with 2017.
While the butterflies may have been relatively scarce, there was no shortage of participants for the world’s largest count of butterflies. Over 60,00 participants recorded an amazing 550,000 individual insects of the 20 target species. This made Big Butterfly Count 2017 by far the most successful yet. And the data gathered by this army of citizen scientists are proving really useful. Recent research led by Butterfly Conservation and Kent University shows that changes in butterfly populations estimated from Big Butterfly Count data match closely with those from much more intensive, transect-style butterfly monitoring. This raises the potential for Big Butterfly Count data to be used alongside more rigorous schemes in assessing the changing fortunes of widespread butterflies, particularly in urban areas and private gardens, both of which are very well recorded in Big Butterfly Count.
Species results 2017
The Gatekeeper (see header photo) secured the top position in the Big Butterfly Count 2017 chart. This is the third time that it has been the most abundant big butterfly count species (it was also top in 2011 and 2015), more than any other species. The Red Admiral (left) achieved its highest ever placing of 2nd (previous best was 5th in 2011). The Meadow Brown took the 3rd spot for the third year running. A poor year for the Large White and Small White saw them drop from 1st and 2nd places in 2016 to 5th and 4th (respectively). The rest of the top ten was made up by the Peacock, Comma, Small Tortoiseshell, Common Blue and Speckled Wood.
One of the stars of the summer was the Red Admiral. After a good year in 2016, numbers of this powerful, migratory butterfly soared during 2017, recording its best ever Big Butterfly Count performance (the only target 
species to achieve a new best in 2017). Numbers of Red Admirals were up 75% compared with the 2016 Count and threefold compared with 2015. Another winner was the Comma (left), which profited from the warm spring by producing a bumper summer generation. It bounced back strongly (up by 90%) from a relatively poor year in 2016, recording its second best Big Butterfly Count ever. The Common Blue and Small Copper also recovered from a very poor 2016.
On the negative side, the three common ‘whites’ all decreased compared with 2016 and seemed thin on the ground. At 12th in the Big Butterfly Count 2017 chart, the Green-veined White (left) slumped to its lowest ever placing. There was no good news for the Small Tortoiseshell, which has been the source of much concern over the past decade or so, or the beautiful Peacock, both of which remained at low levels, very similar to those recorded during Big Butterfly Count 2016.
You can see the full 2017 results and the results for each UK country on the Big Butterfly Count website.
Photos by John Archer (Gatekeeper, Red Admiral, Comma) and Tosca Yemoh (Green-veined White)
