Spotlight On: Arreton Down Nature Reserve

Arreton Down Nature Reserve, Isle of Wight

Clouds of chalkhill blue butterflies, the high-pitched song of the great green bush cricket and breath-taking views across the Isle of Wight make Arreton Down nature reserve the perfect spot to enjoy a warm summer’s day.

Perhaps just as spectacular is the nature reserve’s botanical diversity; the steep southern slope is clothed in wild flowers like wild thyme, vetches and rock rose. This is in part due to the low nutrient soils but this also means the plants appear in miniature. Other examples include the gorgeous pyramidal orchid, the Island speciality early gentian and, later in the summer, eyebright and small scabious. As many as 35 species of wildflower can be found in just one square metre!

If we are to maintain such high levels of diversity in flora and fauna here we must provide a habitat with an equally diverse set of environmental conditions to satisfy the species we’re trying to protect. Our research has shown us that a large number of the more delicate flowers and rarer invertebrates that live at Arreton Down require areas of shorter grass with bare patches of earth that allow the warmth of the sun to reach the soil.

To maintain these short areas of grass Arreton Down is grazed by cattle each winter. Wild rabbits help to maintain the short grass but some hand cutting is also required to keep scrub (such as brambles and saplings) under control. Throughout winter, our dedicated volunteers help to clear any scrub and ensure the nature reserve offers the ideal habitat for rare invertebrates.

The nature reserve also has many disused chalk pits that, if managed appropriately, provide the perfect habitat for such species to thrive. The steep pits allow for shallower soil, shorter turf and seasonal warmth as the steep slopes absorb more of the sun’s rays.

If we and the rest of the back-boned animals were to disappear overnight, the rest of the world would get on pretty well. But if the invertebrates were to disappear, the world's ecosystems would collapse.
Sir David Attenborough
Common blue male butterfly at Blashford Lakes nature reserve

© Bob Chapman

One example of such a species is the chalkhill blue butterfly. This powder blue butterfly is most commonly found in the areas of shorter grass that provide better growing conditions for its larval food plant, horseshoe vetch. The chalkhill blue overwinters as an egg on the ground and once it hatches in spring it feeds on the horseshoe vetch at night. Once it becomes a chrysalis it produces secretions that attract a particular species of ant, which takes the chrysalis back to their nest and look after it until the butterfly is ready to emerge as an adult around late July/ early August. Arreton Down is a very good site for the chalk hill blue and in peak years an incredible 50,000+ butterflies can be seen on the wing! 

And it’s not only the blue butterflies that call Arreton home; brown argus, gatekeeper, small heath, grizzled skipper, green hairstreak and marbled white can also be seen dancing across the downs. It’s also an excellent place to spot birds such as yellowhammer, kestrel, buzzard, green woodpecker and hear the overhead song of skylark. For more information about this nature reserve please click here.

Get involved

If you’d like to volunteer at Arreton Down, or any of our other reserves across the Island, please contact us on 01983 760016, or email volunteer@hiwwt.org.uk