English Visions Butterflies

Summer on Cissbury Ring

Magnificent Cissbury Hill looms over Findon village in both physical and historical terms. Flint mines dating from 3,600 BC can still be seen and the flints themselves have turned up in various parts of Europe and the UK. Today Cissbury is no longer famous for its flint deposits. The site of the ancient fort on top of the great hill has been preserved for posterity by the National Trust and this attracts good numbers of visitors.

A more select group of people know the hill for its famous populations of rare butterflies and these depend on certain specialised downland plants, themselves now in decline. Among the most interesting is horse shoe vetch. It grows at ground level and is the food plant of the Adonis and Chalkhill blues.

These two butterfly species have formed a complex association between themselves, their food plant and ants who guard the larvae in return for sugary secretions from the caterpillar's body. Normally these two species are found on the south facing side of hills where their food plant grows in profusion. For that to happen the grass must be kept short by grazing so that the delicate vetches are not shaded out. A similar situation is true regarding the Fritillaries.Their food plants are violets and once again they can tolerate no shade.Once caterpillars have turned into butterflies they have the task of finding nectar bearing plants. The numerous thistles of various species as well as Bramble and Ragwort provide ample supplies of nectar both for the butterflies and other insects especially hoverflies. Some of these are remarkable mimics of bees, wasps and even hornets. There is a profusion of insect life on Cissbury and it does not matter that so much of it is small and often overlooked.

The "blues" are found in areas managed by the national trust specifically for them. I use the word "managed" because it is so important for these species. Originally the forested slopes of Cissbury and other similar hills in Sussex, would have supported woodland species such as the large Tortoiseshell and Purple Emperor butterflies and the present day proliferation of blues on the hill in summer time would not have existed. As humans settled and began to farm they created a new landscape that was ideal for the grassland species we see today. Grazing by sheep was and remains the most important factor.
The downland plants on which the butterflies lay their eggs have adapted themselves over countless centuries.

Once grazing is removed from an area, even for a short period of time, grasses quickly block out the light and violets and horse shoe vetch disappear, along with the butterflies that rely on them.

Twenty eight species of butterfly have been recorded on Cissbury.

Some people choose to go to the Amazon or Africa to see the beauty of nature but I would argue that there can hardly be anything more impressive than the south side of Cissbury Hill on a summers day.