A Living Boundary

Walk along almost any country lane in lowland Britain and you are following a hedgerow. These lines of thorn, hazel and ivy are so familiar that they are easy to overlook, yet they are among the most valuable pieces of wildlife habitat we have. England alone is thought to hold somewhere in the region of 500,000 kilometres of hedgerow, and while roughly half of that was lost in the decades after the Second World War, what remains still stitches the farmed landscape together.

Most of our hedgerows are far older than they look. Many began as stock-proof boundaries thrown up during the parliamentary enclosures of the eighteenth and nineteenth centuries, while others are the last surviving fragments of ancient woodland, left behind when the land around them was cleared for fields. That history matters: an old hedge can carry woodland plants and invertebrates that have nowhere else to go, and once it is grubbed out, that inheritance is gone for good.

What Makes a Good Hedgerow for Wildlife

Not all hedges are equal. A tall, broad, species-rich hedge with a dense base and a rough grassy margin is a wholly different proposition for wildlife from a low, flailed line of a single shrub.

• Density at the base. Small mammals, nesting birds and hibernating insects need a thick, tangled bottom. A hedge trimmed into a narrow box on stilts offers almost nothing.
• Species diversity. A mix of hawthorn, blackthorn, hazel, field maple, dog rose, honeysuckle and ivy flowers and fruits at different times, so there is food available for far longer.
• Height and width. Two metres or more in height, and ideally a metre and a half to two metres across, gives shelter from wind and rain and space for layered nesting.
• A buffer strip. A two-metre uncultivated margin of tussocky grass beside the hedge is where much of the hunting, nesting and travelling actually happens.

Where one hedge meets another, or joins a wood, a pond or a stream, its value rises sharply. These junctions are the hubs of the network.

Food, Shelter and Nesting Sites

Think of a hedgerow as a year-round larder and larder queue. Blackthorn blossom in early spring feeds emerging bees and hoverflies when little else is in flower. Through summer, the foliage supports vast numbers of caterpillars, which in turn feed nestlings. Autumn brings haws, sloes, hips and elderberries; winter, the black berries of ivy, which ripen late and can be a lifeline for thrushes and blackbirds in a hard January.

Nesting birds rely on different parts of the same hedge. Dunnocks and robins nest low and need the dense base; whitethroats, linnets and yellowhammers sit a little higher in the scrubby growth. A hedgerow with a variety of heights will hold far more pairs than a uniform one.

Mammals use hedges for cover and for travel. Hedgehogs root along the base, bank voles and wood mice nest in the litter, and shrews hunt through the leaf mould. Dormice, where they survive in southern and western counties, depend on hedgerows as much as on woodland, feeding on hazelnuts and blackthorn fruit. Many insects overwinter in the dead stems and hollow twigs, so cutting everything back to the bone each year strips out the next generation.

Corridors Through the Farmed Landscape

This is the hedgerow's greatest gift to wildlife: connection. A hedge is a sheltered highway, letting animals move between woods, meadows and wetlands without crossing open, exposed ground. Bats commute along them at dusk, following the insect-rich edges. Hedgehogs and small rodents use them to disperse, and plants spread along them too, seed by seed.

Gaps matter enormously. A break of ten metres or more in an otherwise continuous hedge is a real barrier to a bank vole or a hedgehog, which will rarely risk the crossing. If you are planning work, keep breaks to a minimum and keep them narrow where you can. Where a hedge does end abruptly at a road, a small planted spur or a scrubby corner can restore the link.

Managing a Hedge Well

Good hedgerow management is mostly about restraint and timing. The old craft of laying — partially cutting the stems and bending them over to weave a living barrier — remains the finest thing you can do for a hedge, because it produces a dense, stock-proof base and stimulates fresh growth.

• Cut on a rotation. Trim one side or one section every second or third year rather than the whole length annually. This leaves some fruit and some taller growth at all times.
• Time it right. Late winter, once the berries have been stripped, is ideal. Avoid March to August entirely — that is the bird nesting season, and it is also an offence to disturb nesting birds.
• Raise the flail. Cutting every year at the same height produces a leggy, gappy hedge. Trim into a rough A-shape, wider at the base.
• Protect the margin. Keep sprays, fertiliser and cultivations out of the two-metre strip, and never scalp the base.
• Rejuvenate tired hedges. Coppicing or laying a neglected hedge back into shape can add decades to its working life.

Watching and Helping

You do not need to own land to make a difference. Learn to read a hedgerow as you walk: nibbled hazelnuts with a neat round hole suggest dormice, while a torn shell points to a squirrel or wood mouse. Look for the fine, papery egg cases of the brown hairstreak butterfly on the youngest blackthorn shoots — a sign of a hedge cut on a gentle rotation. Count the birds singing from the top of a hedge on a May morning, and you have a rough measure of its health.

Recording what you see, and passing it on to your local wildlife trust or county recorder, genuinely helps. So does supporting hedgerow-friendly farming, and pressing for the protection that our oldest hedges deserve. These boundaries have been part of the British countryside for centuries. With a little care and patience, they will go on feeding, sheltering and linking our farmland wildlife for centuries more.