One aspect of our Devon countryside that most of us take very much for granted are our Devon hedges – well known for their height and covering an astonishing 33,000 miles, but a haven for literally hundreds of species of flora and fauna.
These mainly consist of an earth bank faced with stone or turf with shrubs or trees growing on the top. The most common tree species are hazel, hawthorn, blackthorn, holly, oak, ash, beech and sycamore. The landscape of Devon is made up of a large number of small irregular fields, mostly formed between 1150 and 1350. As England’s third largest county, Devon has an astonishing 33,000 miles of hedges, including about a fifth of all the species-rich hedgerows in England. Many of these hedges have been around for centuries; indeed, three-quarters of the hedges in Devon are 600 years old or more. This is confirmed by the presence of plants such as wild garlic, bluebells and dog’s mercury, all characteristic of ancient woodland. It is possible to estimate the age of a hedge by counting the number of different species of trees or shrubs in a 30-yard stretch; for instance, if there are three species, the hedge is around 300 years old.
The wild flowers of the Devon banks in spring are a real marvel. Starting in February/March with primroses and celandines, they are followed by violets and early purple orchids, then the red, white and blue pattern of red campion, stitchwort and bluebells. By June the hedges are alive with foxgloves and cow parsley. These are followed by hemp agrimony, hogweed, rosebay willowherb and meadowsweet. All these plants provide nectar and pollen sources for insects, such as bees and hoverflies, as well as providing seeds for birds in autumn and winter. Bumblebees frequently nest and hibernate in hedges. Banks and ditches provide cover for grass snakes, lizards, slow worms and also for frogs, toads and newts. Mammals like hedgehogs, stoats, weasels and badgers use hedges for cover and food. Autumn is a very productive season for Devon hedges, with a free feast on offer, including blackberries, hazel nuts, and sloes.
It is difficult to fully appreciate the huge importance of Devon’s hedges to wildlife. One expert who studied a 90-yard stretch of hedge in Devon found over 2000 (yes, 2000!) different species of plants and animals present in the hedge. Some of the rare or special species found in Devon’s hedges include the Devon whitebeam, Plymouth pear, Brown hairstreak butterfly, Cirl bunting, and Greater horseshoe bat.
The Brown hairstreak butterfly lays its eggs on young blackthorn twigs in autumn, mainly in hedges or, less often, woodland edges. When the eggs hatch in spring the caterpillars feed on blackthorn in May and June before pupating. The adult butterflies fly in August and September. This butterfly has declined hugely across England and Wales in recent decades due to loss of hedgerows and to repeated severe flailing; despite this, it is still found in many parts of Devon. Farmers who wish to conserve brown hairstreaks should aim to trim their hedges on a three-year rotation, only cutting a third of hedges in any one year. We should remember, however, that without farmers we would have no hedges!
Devon is a national stronghold for the Hazel dormouse, a European Protected Species. Dormice are found around woodland edge and in scrub and Devon's hedges make ideal habitat for them. They prefer dense bushy hedges which provide safe nesting conditions (dormice spend most of their lives asleep!). Hedges with plenty of thorny or prickly species such as blackthorn, holly, gorse, wild rose and bramble are particularly favoured. Dormice feed on a wide range of food including insects, flowers and fruits. Farms with hedges at different growth stages are likely to provide all the resources dormice need.
Birds that regularly use Devon banks for nesting include the Dunnock (also known as the Hedge Sparrow), Robin, Blackbird, Song Thrush, Whitethroat, Pied Wagtail, Yellowhammer, Chaffinch, Linnet (and many other finches), and the Cirl Bunting (mainly on the coast). It has been estimated that there may be a pair of nesting birds about every 100 yards of hedge on average. If that were true for Devon, there could be as many as half a million pairs of birds breeding in Devon’s hedges. However, the structure of the hedge is very important. Hedges which are allowed to become overgrown over several years have a much higher value for wildlife than those cut back every year.
Thanks are due to the Devon Hedge Group’s very informative website (http://devonhedges.org) for much useful information. Further details about hedges can be found on their website; there is usually a Devon Hedge Week in the autumn.
Wildlife is constantly changing. October sees the departure of the remaining Swallows and House martins heading for Africa, and the arrival of winter visitors from Scandinavia – Redwings and Fieldfares, as well as wildfowl and waders from further north that winter in Britain.
Anthony John