Butterflies at Runnymede and Ankerwycke

Last year at Runnymede no less than 19 different species of butterfly were spotted during surveys. Surveys are undertaken by our dedicated volunteer Cathy, who walks a transect through Runnymede every week between April and September. Everything she spots she records, and this information is all fed into a countrywide database run by the UK Butterfly Monitoring Scheme. The transect passes through all the different habitat types, and different species tend to be spotted in different locations depending on where they can find their main foodplants.

First signs

The first species of the year normally appear around March – a welcome sight indicating spring has arrived after the long cold winter. These early appearances usually come from the brimstone, peacock, comma and small tortoiseshell as the adults of these species all hibernate here through the winter and emerge as soon as the weather is warm enough.

It doesn't always follow a pattern, though - last year at Runnymede a red admiral was spotted by one of our rangers on an unusually warm and sunny day in January. Until recently, red admirals have rarely overwintered in the UK, preferring to spend the winter on the continent where it is warmer, but climate change has led to more of them successfully surviving the winter here. Other butterflies spend the winter either as eggs, caterpillars or a chrysalis.

Spring flutters

By April, a bigger variety of adult butterfly species can be spotted. Orange tips and small white can often be seen in the hay meadows surrounding Langham Ponds, while speckled woods are found fluttering around in the dappled sunlight of Coopers Hill Woods and the wet woodland along the River Thames at Ankerwycke. By May the common blues have appeared, enjoying the meadows where the distinctive yellow bird’s-foot trefoil wildflowers are plentiful.

Summer surge

The summer months from June to August are dominated by the meadow brown, which accounted for over half of the total number of sightings in the 2016 Runnymede butterfly surveys. But you should also keep an eye out for gatekeepers at this time of year, as at first glance the two species can easily be confused. Many species can be seen right through until October, although by November most have disappeared for the year, with only the odd red admiral spotted around.

An ideal habitat

Runnymede and Ankerwycke are so popular with butterflies because they provide so many of the foodplants needed by butterflies to lay their eggs on so the caterpillars can feed when they hatch.

Butterflies have four stages in their lifecycle – the egg, the larval stage (the caterpillar), the pupal stage (the chrysalis), and finally the adult stage (the belle of the ball!). Butterflies have very specific diets, so if the adults do not lay their eggs on the right type of plant, then the caterpillar is unlikely to survive when it hatches as it needs to be able to eat a lot before they move into their pupal stage.

Luckily, at Runnymede there is plenty of food to go round including bird's-foot trefoil for the common blues, grass species such as fescues and poas for the meadow browns, nettles for the peacocks and small tortoiseshells, holly and ivy for the holly blue, and cuckooflower for orange-tips and green-veined whites.

Butterflies in trouble

Unfortunately, data suggests that butterflies are suffering a serious and long-term decline in both occurrence and abundance across the UK. According to Butterfly Conservation, 2016 was the fourth worst year on record, with most species experiencing some sort of decline. Climate change is thought to be a playing a part, with increasingly mild winters making many butterflies more vulnerable to disease, predation, or disruption of their overwintering behaviours.

At Runnymede and Ankerwycke we are making sure we look after the habitats and foodplants the butterflies need to reproduce and survive to give them the best chance possible of doing well here in the future.