Butterflies

Two butterflies that are particularly special to see are those whose numbers are declining towards extinction along The Ridgeway – the Speckled Wood and Chalk Hill Blue. As its name suggests, the Speckled Wood is often found in the dappled shade of trees. It is an inquisitive or even friendly butterfly, frequently accompanying walkers for quite long distances as it repeatedly flies ahead to wait until the walker catches up! In contrast, the Chalk Hill Blue seeks out open, grazed chalk grasslands where it can find Horseshoe Vetch as a plant to feed its caterpillars. This is also true of another ‘priority species’ found along The Ridgeway – the Adonis Blue – although the Adonis has a further specialism whereby its chrysalis is adopted by ants which bury it underground to protect it from predators!

In contrast, numbers are increasing for the Silver-washed Fritillary and the Dark Green Fritillary and reporting sightings from new locations will help Butterfly Conservation and others to track changes. Both butterflies can be found at Grangelands, Pulpit Hill and Aston Rowant National Nature Reserve. There are some useful and free mobile phone apps to help people identify and record what they see outdoors, including the iNaturalist app.

The best places to see high numbers of butterflies are, in Oxfordshire: Swyncombe Downs, Aston Rowant National Nature Reserve and Oakley Hill, and in Buckinghamshire: Coombe Hill, Kop Hill, Brush Hill and Whiteleaf, Grangelands and Rifle Range. The absence of Wiltshire locations may reflect a lack of reporting about butterflies, rather than an absence of butterflies themselves. Barbury Castle is a key place at the western end of The Ridgeway to see many different species of butterfly, as well as Chequers Knap and Incombe Hole in Buckinghamshire.

Time of year is significant when looking for butterflies, although Brimstone, Small Tortoiseshell, Peacock, Comma, Orange-tip, Small White, Green-Veined White, Holly Blue and Large White fly many months of the year. The butterfly year starts with Brimstone and Small Tortoiseshell in late February, closely followed by Peacock and Comma. Holly Blue is the earliest blue butterfly to emerge in the year and so can reliably be identified until mid-May when things get busier with the Small Blue and other species. The Small Blue‘s larval plant is Kidney Vetch and good places to look for it are Swyncombe Downs in Oxfordshire and Pitstone Quarries and College Lake in Buckinghamshire.

Unsurprisingly, Common Blue is one of the most common species to spot along the Trail and it appears in May. The male and female look different so don’t mistake them for different species! The Meadow Brown is another frequent species and iconic of the English summer countryside. It flip-flops about on hot sunny days amidst tall grasses and can be seen in profusion from mid-June through to the end of August. The male can easily be confused for a Ringlet so look for the eye spots on the underwing of a Ringlet.

Some species, such as the Silver-Spotted Skipper, have very specific habitat requirements and so will only be as widespread as their habitat. The habitat-specialist Silver-Spotted Skipper has found what it needs at Swyncombe Downs, Aston Rowant National Nature Reserve, Watlington Hill and Grangelands. In the past, Aldbury Nowers in Hertfordshire was also known for this butterfly until scrub encroached over the grassland. The Silver-Spotted is one of several Skipper species which have a distinctive ‘jet fighter’ arrangement of their wings when at rest and hooked tips to their antennae.

Some butterflies are migrants, including the Painted Lady which has to be a strong flyer since it migrates every year from North Africa and Southern Europe! It doesn’t over-winter in the UK although it does breed here. Another migrant to be seen along The Ridgeway is the Clouded Yellow.

With such a variety of butterflies along the Trail, there is real opportunity to manage The Ridgeway as an ecological corridor so that it provides habitat for butterflies and other insects and also acts as a movement corridor for species needing to move northwards due to climate change. Projects along the Trail to boost biodiversity in the verges, such as the experimental plots managed with the University of Oxford at Bury Down in Berkshire, are important in encouraging butterflies and providing the public with spaces to enjoy them.

Notes: Much of this information comes from a report by Andy Spragg on behalf of Butterfly Conservation.

More information about famous Ridgeway naturalists and chalk grassland plants is available in other Top 50 entries (not all Top 50 entries will be available until end of December 2023).

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