British farmland butterflies bounce back after 2013 summer

The warm and sunny summer of 2013 enabled British farmland butterflies to bounce back from a crash in numbers in 2012, a new survey has found. Results of the Wider Countryside Butterfly Survey (WCBS) show that the majority of farmland species have recovered after the worst year on record for butterflies in 2012, when 52 out of 56 British species monitored suffered declines as a result of miserably wet weather. Individual species that recorded an increase in 2013 included the brimstone, common blue, small and large skipper and small tortoiseshell.

The annual survey, conducted by a coalition of conservation agencies aiming to assess the health of butterfly populations across the wider countryside, counted butterflies in more than 850 areas of 1 square-km in England, Wales, Scotland and Northern Ireland during July and August.

Recorders saw an average of 85 butterflies of five species per survey during the two-month period – almost double the numbers recorded in 2012.

After a harsh winter and delayed spring, the summer of 2013 was among the 10 warmest summers since records began, with 588 hours of sunshine making it the seventh sunniest summer. A prolonged heatwave in the middle of July saw temperatures regularly passing 30C. In contrast, 2012 was the UK’s second wettest year on record, with downpours and flooding.

The small tortoiseshell, which has suffered an ongoing decline, recorded its best summer since the start of the survey, which began in 2009. More than 6,833 individuals were counted, with the butterfly seen in 80% of squares compared to just 40% in 2012.

Small Tortoiseshell

In 2012, numbers of the common blue plummeted by 60% but the species enjoyed a good year in 2013 with an average five-fold increase in abundance per square surveyed. The small copper and brimstone also thrived and were both more widespread and abundant than in the previous year.

The large white and small white butterflies, commonly known as “cabbage whites”, were also recorded in large numbers with more than twice the number of large whites counted per square and five times the number of small whites in 2013 than in 2012.

Butterflies play an important role in the ecosystem as pollinators and as prey in the food chain, and are considered good indicators of biodiversity.

Wild Purbeck

There are few locations where I have enjoyed walking more than the Purbeck coast in Dorset. Miles of rolling grassland peppered with gorse and other scrub and an abundance of wild flowers. The coastal path west of Lulworth is a haven for wildlife.

The west arm of Lulworth Cove

The coastal path just east of Durdle Door

I saw several species of butterflies as I wandered along the path. A single Adonis Blue Lysandra bellargus landed close by, the most brilliant blue colour and the rarest of our downland blues. A privilege to see this beauty. Several silvery-blue Chalkhill Blues Lysandra corridon drifted over grass no doubt looking for the few knapweeds and scabiouses still evident. Small Whites Pieris rapae showed in abundance as too did Small Tortoiseshells Aglais urticae and a single Gatekeeper Pyronia tithonus.

As I watched the butterflies something entered my peripheral vision and I looked skyward just in time to lock my binoculars on a magnificent Peregrine Falcon Falco peregrinus drifting effortlessly on thermals as he flew by west to east. Following his flightpath brought a hovering Kestrel Falco tinnunculus into view. Further along the track I met up with one of the local rangers and asked the usual "Seen anything?" He pointed out a number of Yellow Wagtails Motacilla lava resting on nearby fence-posts, summer visitors no doubt thinking about their return journey south. Further along the fence we spotted a single Whinchat Saxicola rubetra, another summer visitor. We parted company and I wandered on past an area of low scrub and was lucky to see a skulking Stonechat Saxicola torquata. But the highlight had to be a pair of Ravens Corvus corax, the largest by far of the black crows, big-headed and wedge-tailed.

In February 2012 the Wild Purbeck area was designated as one of 12 Nature Improvement Areas across the country. It is an area of outstanding beauty that provides the naturist with a wealth of wildlife to see. Keep your eyes peeled and remember to keep looking up; you never know what might be passing overhead! 

The Holly Blue

The most frequent butterfly visitor to our garden is the Small White Pieris rapae, two or more can be seen throughout most days. This year I have recorded the Gatekeeper Pyronia tithonus, also know as the Hedge Brown, the Small Tortoiseshell Aglais urticae, the Painted Lady Vanessa cardui (cracking latin name) and the Peacock Inachis io. But my favourite has to be the diminutive Holly Blue Celastrina argiolus.

The butterfly in the photo is a female Holly Blue that visits our garden fairly regularly, here seen on a jasmine plant. Not a brilliant pic because she refused to open her wings fully as I repeatedly pressed the shutter release. But the black wing tips help to identify this as a female. The lilac-blue male can be confused with the Common Blue Polyommatus icarus. The black borders of the Holly Blue female are bolder near the wing tips.

Populations of the Holly Blue vary greatly from year to year due mainly to a combination of the climate and the presence of a parasitic ichneumon wasp called Listrodomus nycthemerus. This black and yellow insect parasites only the Holly Blue and kills large numbers of its caterpillars.

The parasitic wasp Listrodomus nycthemerus