A sky that used to be busier

Swallows drift in from early April, usually the first of the two to arrive, and swifts follow in the first days of May, screaming in tight, dark flocks above village roofs. Both have travelled thousands of miles from southern Africa, and both are now in real trouble. Swifts have lost well over half their British breeding numbers in a generation, largely because the old, draughty buildings they nested in have been sealed, re-roofed or fitted with blocks that close up the gaps. Swallows have lost open barns, cattle yards and muddy farm ponds. The good news is that these are birds we can genuinely help, and rural homes sit at the heart of it.

What swifts are really looking for

A swift does not perch. It has tiny legs, tucked-up wings and a single aim: to find a dark cavity at least five metres up, with a clear drop underneath so it can launch itself into the air. Traditionally that meant a gap under a slate, a hole behind a fascia board or a space in a thick stone wall.

• Height matters. Anything below four to five metres is unlikely to be used, and the box or gap should be sheltered from the prevailing wind and the worst of the afternoon sun. A north or east-facing wall is ideal.
• Fit a swift box or brick. Purpose-made boxes have an internal space of roughly 30cm long, 15cm high and 13cm wide, with an oval entrance of about 65 x 30mm. Bricks built into a wall achieve the same thing and are invisible from the house.
• Play a call lure. Swifts are highly sociable and follow each other to nest sites. A small speaker playing swift calls at dawn and dusk from late April to early August is the single most effective way to draw birds to a new box.
• Be patient. Young swifts take two or three years to return and breed, so a box installed this spring may sit empty for several seasons before it fills.

Making room for swallows and house martins

Swallows want something quite different: a ledge or beam inside an open building, two or three metres up, close to the ceiling, with a clear way in and out. Old stables, cart sheds, outbuildings, garages with a small pane removed and open-fronted barns are all classic sites. A simple shelf about 15cm wide and 10cm deep, fixed to a beam, gives a pair a foundation to build their mud cup on.

House martins nest outside under the eaves, often at the gable end, and are the most colonial of the three. Artificial cups fixed directly under the overhang, and positioned so they are sheltered from driving rain, are readily adopted, particularly if you put up two or three near each other rather than one on its own. Keep a hosepipe away from the wall beneath them in wet weather; mud nests can slump in a downpour.

Mud, the forgotten ingredient

Swallows and martins build with pellets of fine, wet earth, and a shortage of mud is a real limiting factor on many farms. You can fix that in an afternoon.

• Keep a shallow puddle damp through May and June. A tray, a sunken basin or a worn patch of bare clay ground beside a water butt all work.
• If your soil is sandy or chalky, tip a bag of clay soil into a hollow and keep it sodden. Add some dry grass to the mix and they will use it.
• Leave a patch of bare, compacted earth near a gate or track where vehicles churn it up. It is free nesting material.

An insect-rich sky

Swifts feed at altitude, but swallows and martins hunt low over meadows, ponds and cattle, and all three need a constant supply of flying insects. A small pond or boggy corner will produce clouds of midges and mayflies. A strip of rough grass and wildflowers left unmown through the summer, a dung heap, a log pile and a few native shrubs will all add insects.

The most important rule is simply to stop taking them away. Avoid insecticides and weedkillers in the garden, let a corner of nettles stand, and cut back on nighttime outdoor lighting, which draws and exhausts moths and other insects. Hedgerows and mature trees give shelter on windy days, when insect prey is pushed into calm, sheltered air.

Good housekeeping, and a little patience

Time any roof repairs, painting or re-pointing for September to March. Disturbing an occupied nest is not just unkind, it is an offence: swallows, martins, swifts and their active nests are protected under the Wildlife and Countryside Act 1981, and the nests of swallows and martins cannot be removed while in use.

If droppings beneath a nest become an issue, fix a shelf or board below rather than destroying the nest. Keep cats indoors at dawn and dusk in summer, and never netting beneath eaves — it is the single biggest killer of swift nest sites. Put boxes up now, keep the mud wet, leave the grass a little longer, and give the birds a few years. The first dark shape screaming past your gable will be more than worth the wait.