Preparing Your Garden for Returning Swifts

Why Swifts Need a Helping Hand

Swifts are among the last summer migrants to arrive in Britain, usually appearing in the first week of May after a journey of some 6,000 miles from central Africa. They stay just long enough to raise a single brood before heading south again in August. For many of us, their screaming parties wheeling over rooftops are the sound of high summer itself.

That sound is becoming rarer. Swift numbers in the UK have fallen by more than half in the past twenty-five years. The reasons are tangled but familiar: fewer flying insects, and fewer places to nest. Swifts are fussy tenants. They nest almost exclusively in cavities in buildings — under eaves, behind loose tiles, inside old ventilation holes — and they are fiercely faithful to a site once they have used it. Lose that site and a pair may not breed at all.

The good news is that gardens matter more than most people realise. A swift's foraging range can extend a mile or more from the nest, so the insects you encourage in your borders and pond are genuinely part of the picture. Here is how to get ready before they arrive.

Get the Timing Right

Swifts are only with us for around three months, so preparation is best done in late winter and early spring, before the first birds appear. Work done in April is ideal; anything after mid-May risks disturbing pairs that have already settled.

• February to March: plan your planting, clean and repair nest boxes, and check that any existing nest places are still intact.
• Late March to mid-April: put up new boxes or add a call system to draw birds in.
• Late April: listen at dusk for the first screaming parties. If you hear them, you have a few weeks to attract interest.
• August: once the young have fledged, that is the moment for any bigger structural work.

Plant for Insects, Not Just for Looks

Swifts feed entirely on airborne insects — aphids, beetles, flies, midges and tiny moths swept up on the wing. A garden rich in these will pull birds in from a wide area. The trick is to have something flowering from April right through to September, so there is never a hungry gap.

Native plants are the safest bet because local insects have evolved alongside them. Good choices for a swift-friendly garden include oxeye daisy, field scabious, knapweed, yarrow, wild marjoram, foxglove and purple loosestrife. If you have room, a patch of long grass left unmown will support the larvae of many flying insects, and it costs you nothing but a little untidiness.

Herbs are quietly excellent. Leave a few chives, fennel, dill and mint to flower rather than cutting them back — their tiny blooms are magnets for hoverflies and small wasps, both of which end up in a swift's beak. Umbellifers such as cow parsley and fennel are particularly productive.

If you can manage it, a small pond is the single most valuable addition. Even a buried washing-up bowl with a few stones and some native oxygenators will draw in damselflies, caddisflies and midges, and swifts will hunt directly above the water.

Check and Site Your Nest Boxes

Purpose-built swift boxes are the practical answer for most homes, since few of us have the crumbling eaves swifts traditionally favour. Look for a box with a shallow, oval entrance and a deep, dark interior — swifts like a nest chamber around 30cm long and 15cm wide. A starling-proof box with an entrance sited under an overhang will reduce competition.

• Height matters. Aim for at least five metres up, with a clear drop below so birds can swoop in and out.
• Shelter from the sun. Avoid a south-facing wall that bakes in July; east or north-east is usually kinder.
• Give them a clear flight path. Trim back anything within a few metres of the entrance.
• Cluster them. Swifts are colonial. Two or three boxes together are far more likely to be used than a single box on its own.
• Check existing nests. If you already have a box, clear out old nesting material in March and check the fixings are sound.

A call system — a small speaker playing swift calls at dawn and dusk during May — can be remarkably effective at drawing passing birds to a new site. It is worth considering if your boxes have stood empty for a season or two.

Make Small Changes That Add Up

You do not need a large garden to help. A few modest tweaks will benefit swifts and the wider world of insects they depend on.

• Leave a corner of nettles and brambles; they support a surprising range of flying insects.
• Skip the pesticides. Aphids, greenfly and caterpillars are all food, not problems.
• Plant a native tree if space allows — birch, rowan or crab apple all attract insects in quantity.
• Let a patch of lawn grow long over summer and cut it in autumn.
• Keep cats indoors at dawn and dusk during the breeding season, when young swifts are most vulnerable.

Swifts are patient birds, but they are not unlimited in their patience. A site left undisturbed and a garden humming with insects give them the best possible chance. Put the work in now, and by the middle of May you may hear that unmistakable scream overhead — and know you had a hand in it.