Robert Wolton is an ecologist who has written extensively about hedgerows and the wildlife within, including an upcoming book, Hedges, which will bring together decades of research and personal experience, much of it from his own farm in Devon. Butterfly Conservation is proud to work alongside Robert as part of Hedgelink, a cross-organisational group advocating for hedges across the UK. Here, Robert shares his love of the humble hedge.

It’s easy to overlook the abundance of wildlife in a good hedge. As you walk along it, you will be aware of the shrubs and trees and may see a few birds flitting between branches, perhaps the odd rabbit or two. If it’s summer, you may be delighted by flowers in the margins and the occasional butterfly or bumblebee. But the myriads of smaller forms of life, most of the fungi and all the nocturnal insects and mammals, will probably escape your notice.  You may well wonder what all the fuss is about, why ecologists keep banging on about how important hedges are for nature.  Sure, they may link woods, offer safer passage than crossing open fields, but are they, in all truth, much use otherwise?

Without doubt! We are just too big and too fast to take in the extraordinary wealth of wildlife living in even a half decent hedge.  You have to be prepared to look very closely.  I have done just that, spending two years finding and counting as many species as I could in a single hedge on our farm in Devon. It was not a full-time occupation, but most days I visited the hedge, which I chose for no better reason than it was a typical farm hedge within 50 metres of our front door, and many an evening I spent examining specimens collected from a range of traps. I was blessed with a great deal of help from experts.

The result – 2,070 species. A figure that causes most to take a step back. Surely not? But yes, that’s right, and all big enough to be seen with the naked eye. Even then it’s not the final tally. Hundreds of species of parasitic wasps remain to be identified, and I’m sure there are many more beetles and fungi to be discovered. My guess is that the true total is nearer to 3,000. In just one hedge!  My hedge, 85 metres long, has one sixth of all the flies, moths and caddisflies recorded in the British Isles. How many more may whole networks contain?

Is there a catch, perhaps? Do hedges in some way ensnare species, wasting their energy, reducing their reproductive success? All the evidence suggests otherwise. Apart from one large white butterfly that acted as if my hedge was merely a barrier to its flight across the countryside, in its search perhaps for a cabbage patch, everything else I saw, and everything I read, suggests that the hedge provides valuable resources of one sort or another for the great majority of the 2,000+ species. Maybe food, maybe a place to lay eggs or build a nest, to find a mate, or perhaps shelter from wind, sun or predators. Whatever, it is abundantly clear that hedges can, if in reasonable condition, be an excellent wildlife habitat in their own right, as well as helping many creatures move safely through the hostile landscape typical of intensive farming.

I’m often asked what types of hedges are best for wildlife? It’s a difficult question to answer because different species like different sorts of hedges. Whitethroats, Linnets and Yellowhammers like short ones, Blackcaps tall ones, Greenfinches wide ones. So, the question should really be, what types of networks are best? Simply put, structurally varied ones. But if I’m cornered into giving my opinion about individual hedges, the first point I make is that they should be more than just a line of shrubs.  Occasional hedgerow trees and flower-rich or tussocky-grass margins add huge value. Any bank or ditch is an additional bonus. So much of the focus on hedges these days is all about the line of bushes, yet this on its own supports just a fraction of the wildlife a good hedge can hold. Most butterfly caterpillars feed on the herbs and grasses growing at the base of a hedge, not on the shrubs and trees. We need to broaden our focus.

Next, the wider a hedge – bushes, trees, margins, banks and ditches combined - the better. Those terribly thin lines of thorn bushes where the land is cropped or heavily grazed right up to the base, the wind whistling through them, are a shadow of what they should be. Let’s encourage hedges to grow wider: the impact on food production is likely to be minimal, it may even be beneficial by boosting populations of pollinators and the predators and parasites of crop pests.

Along similar lines, dense bushy hedges tend to be better for wildlife than tall straggly ones. You should not be able to see through a hedge in the summer. Dense hedges are where most of our smaller birds choose to nest - finches, warblers, thrushes, Wren, Dunnock - Hazel Dormice too.  They also provide far better shelter and safety from predators than open-structured ones, just as much for butterflies, hoverflies and other insects as for vertebrates. Best of all are hedges where bramble and tangles of roses are allowed to grow along the edges.

That brings me on to flail trimming. No other hedge issue causes so much anxiety. To many, flails are seen as brutal destroyers of life. But to farmers they are a superbly useful means of keeping hedges in check – nothing else is nearly as efficient or economic. The motivation may often be to keep farms looking neat and tidy as a sign of good husbandry, but the result, if sensitively used, is hedges in the thick bushy condition favoured by so much wildlife. If hedges are not cut hard back to the same point each time they are trimmed but allowed to expand just a few inches, and preferably not cut every year (unless necessary for access and safety), then they can remain healthy and support an abundance of wildlife for many years. I flail trim the hedge with 2,070 species every three years or so. Each time I do so the shattered ends look unsightly, but our native trees and shrubs are extraordinarily resilient to such damage and by mid-summer you’d be hard pressed to tell they’d recently been shorn of several years’ growth. If I did not flail cut the hedge, then I would have to lay it much more often, an expensive and time-consuming matter, and for most of the time it would not be as thick and bushy.

On the one hand we need to accept that shattered ends are the short-term price we pay for dense, bushy, hedges; on the other hand, we need to learn to love the unruly hedge. Then they can be wonderful for wildlife.

Robert Wolton

Find out more about hedgerows and how important they are for butterflies and moths here.