Swift boxes and house martin nest cups on a UK house

Swifts and house martins are not garden birds in the way a blue tit is. They do not come to feeders, and the small-hole box in the nest box guide is not for them. What they need is the building itself: high walls, eaves, gaps under the roof. If you want to help them, you are working on the house, not the garden.

This page is drawn from three RSPB pages opened on 14 November 2026: Create a high home for Swifts, birds nesting in your roof or eaves and the house martin species page. We did not open a swift charity page, so specialist detail is pointed to rather than copied.

Two different birds

Swifts nest inside the building. The RSPB’s roof page says swifts seek dry, safe sites just inside the roof, usually entering where overhanging roofing felt is torn. They rarely walk around inside a roof because their legs are very short. A swift box or swift brick copies that: a dark cavity with an entrance high on the wall.

House martins nest on the outside. The RSPB’s species page says they usually build mud nests under the eaves of homes and buildings, a cup made of mud on outer walls, and that they tend to nest in colonies, sometimes several nests side by side. They are summer visitors that come to the UK to breed. The page also says house martins have declined and are on the UK Red List of Conservation Concern.

Both are building-dependent and both like company. That is why a single box on a garden fence does nothing for either.

Swift boxes and bricks

The RSPB’s swift page gives the siting rules:

• Height. At least 5 m (16 feet) above the ground.
• Under the eaves. On the wall of a building, tightly under the eaves where the roof overhangs the wall.
• Easy to fly into. Swifts fly down and then up to the nest at speed, so the approach needs to be clear.
• Out of direct sun. On a wall facing north, east or somewhere in between.

A swift brick is built into the wall rather than fixed to it. The RSPB says that during major renovation a special swift brick can be built into the outer wall, but it should only be done by a qualified builder. If you are planning work on an older house, that is the moment to ask about one.

We have not opened a page that gives box dimensions, entrance shapes or a guaranteed time to occupation, so there are none here. Swift specialists publish that detail; ask a local swift group or the RSPB before buying.

House martin nest cups

An artificial nest cup is a ready-made mud-style nest that is fixed under the eaves, intended to persuade martins to settle. The species and roof pages describe where martins build naturally: high under the eaves on the outside wall. A cup belongs in the same place.

The RSPB’s roof page also deals with the practical downside. Droppings collect below a martin nest. Their answer is a shelf placed roughly two metres underneath the nest to catch them, rather than removing the nest. We have not opened an RSPB page that gives cup siting by compass direction, so we do not give one.

Because martins nest in colonies, a cup on a house that already has martins nearby is more likely to be noticed than one on a street they never visit. We are not promising occupation; nothing we opened does either.

Existing nests come first

The most useful thing for both birds is often not a new box but leaving the old site alone. Torn felt that swifts use, or a row of martin nests under a gutter, can disappear in a single day of roofing work.

The law is clear on active nests. Section 1 of the Wildlife and Countryside Act 1981 makes it an offence in England and Wales to take, damage or destroy the nest of any wild bird while it is in use or being built; the Scottish version adds “otherwise interferes with”. The RSPB’s roof page says it is an offence to intentionally take, damage or destroy any active wild bird’s nest in the UK, and that you must wait for the chicks to leave before removing a nest or blocking its entrance.

On timing, the RSPB says do not begin building work if you know birds are nesting, and if you must stop birds getting into your home, wait until the winter months when they are not nesting. If work cannot wait, they point to Natural England, NatureScot, Natural Resources Wales or DAERA for guidance. We are not in a position to tell you whether your project needs anyone’s consent; ask them.

Sparrows and starlings in the same places

The RSPB’s roof page says house sparrows and starlings are the species most likely to share your home, usually getting into the roof through a gap between the tiles and the gutter. If sparrows are what you actually have, a terrace under the eaves is the better fit. See sparrow terraces and open-fronted boxes.

Where the garden helps

Swifts and martins feed on flying insects. A garden with flowering plants, long grass in places and a pond produces more of them. That is the broader idea in a wildlife-friendly garden, and it helps these birds even though they will never land on your lawn.

How high does a swift box need to be?

The RSPB’s swift page says at least 5 m above the ground, tightly under the eaves, on a wall facing north, east or in between, with a clear approach.

Can I take down house martin nests because of the mess?

Not while they are in use or being built; that is protected by law. The RSPB suggests a shelf about two metres below the nest to catch droppings, and any work to stop birds getting in should wait until the winter months.

Will a swift box work on my garden fence?

The RSPB’s advice is for the wall of a building, high under the eaves. A fence is too low for the height they give.