If birds are nesting in your roof right now, the short answer is: you have to leave them alone until the young have fledged. It’s not a matter of preference — all wild birds, their active nests and their eggs are legally protected in the UK.
Once the season is over, you can block the gaps. Here’s how to do it properly, and how to work out what you’re dealing with.
The essentials
- Active nest: leave it. Blocking access is an offence
- Breeding season: roughly March to August; swifts often into September
- Safe window for roof work: September to February, once the nest is empty
- Some species have extra protection — check before doing anything
- Damage concerns: usually less than people fear, but worth inspecting
What the law says
Under the Wildlife and Countryside Act 1981, it is an offence to:
- Intentionally kill, injure or take any wild bird
- Intentionally take, damage or destroy the nest of any wild bird while it is in use or being built
- Intentionally take or destroy the eggs of any wild bird
Blocking the entrance to an active nest — trapping adults out or chicks in — falls under this. So does removing tiles or fitting mesh while birds are nesting behind it.
Some species are listed on Schedule 1, which adds protection against intentional or reckless disturbance while nesting — a higher bar than for other birds. Barn owls are among them. If you think you have anything unusual, get advice before touching anything.
Penalties for offences under the Act can include substantial fines and, in some cases, imprisonment.
Which bird is it?
This matters, because the timing and the conservation picture differ.
House sparrow
Where: under roof tiles, in soffit gaps, behind fascia boards.
Signs: constant chattering, groups coming and going, untidy straw and feather nest material sometimes visible at the entrance.
When: April to August, often two or three broods.
Note: UK house sparrow numbers have declined substantially since the 1970s and the species is Red Listed. Loss of nest sites in modern buildings is considered part of the cause.
Starling
Where: cavities under tiles, in soffits, behind fascias.
Signs: noisy, chattering, whistling and mimicry. Very obvious once chicks are being fed.
When: April to June, usually one brood.
Note: also Red Listed, with a substantial UK decline.
Swift
Where: high up, under eaves and in roof cavities. Enters at speed through a small gap without landing first.
Signs: screaming parties of dark, scythe-winged birds circling the rooftops on summer evenings. Almost no visible mess — swifts are exceptionally clean nesters.
When: arrive around late April/early May, leave by early August, occasionally later.
Note: UK swift numbers have declined severely and the species is Red Listed. Loss of nest sites during roof renovation is a recognised factor. Swifts return to the exact same nest site year after year — block it and that pair may never breed again.
House martin
Where: a distinctive mud cup nest built on the outside, tucked right under the eaves.
When: May to September, often two broods.
Note: Red Listed. It is an offence to knock down an active nest, and old nests are often reused the following year.
Pigeon or jackdaw
Where: chimneys, larger roof voids, open lofts.
Signs: substantial twig accumulation. Jackdaws can drop large amounts of nesting material down a chimney, which is a genuine fire risk if the flue is in use.
Note: still legally protected while nesting, despite being less popular.
Is it actually causing damage?
Often less than people assume, but worth checking honestly.
Usually not a problem: sparrows, starlings and swifts nesting in an existing cavity. They use gaps that are already there and don’t create them.
Worth investigating:
- Blocked gutters or downpipes from nest material — can cause damp
- Jackdaw nests in an active chimney — a real fire and carbon monoxide risk. Get the flue swept and capped after the season
- Displaced tiles or damaged felt — usually pre-existing, and the reason the birds got in
- Insulation disturbance in a loft void
The birds are typically a symptom of an existing gap, not the cause of it.
What to do now (during the season)
- Leave the nest alone. No blocking, no netting, no scaffolding work at that spot
- Note exactly where the entrance is so you can find it later
- Note the species if you can
- Check gutters below for material that could cause damp, and clear only where you can do so without disturbing the nest
- Book any roof work for autumn
- If the flue is a fire risk, don’t use it, and arrange a sweep once the season ends
Most nests are occupied for a matter of weeks. It’s a shorter wait than it feels.
What to do afterwards (September to February)
Once you’re certain the nest is empty and the season is over:
- Confirm it’s genuinely unoccupied — watch for a few days at dawn and dusk
- Remove old nest material and clear the cavity
- Repair the underlying gap — replace tiles, refit soffits, repair fascia boards. This is the permanent fix
- Fit eaves combs or mesh to close gaps under tiles
- Cap the chimney if jackdaws are the issue
- Get roof work done in this window, not in spring
Tell your roofer or builder before work starts. Contractors renovating in spring and summer routinely block nest sites without realising it’s an offence. A conversation beforehand prevents both a legal problem and a lost nest site.
The alternative worth considering
Every species listed above is in decline, and lost nest sites in buildings are a recognised cause. Modern construction and renovation have systematically sealed off the cavities these birds evolved to use.
If the nest genuinely isn’t damaging anything, one option is simply to leave it. Sparrows and swifts are quiet neighbours; swifts in particular make almost no mess and are present for only about three months a year.
If you do need to close a gap, consider providing a replacement:
- Swift bricks — built into a wall, invisible from outside, and the recommended mitigation when a swift site is lost
- Swift boxes under the eaves
- Sparrow terraces — multi-chambered boxes, since house sparrows nest colonially
- Starling boxes — 45mm hole, fixed high
- House martin cups — artificial nests fixed under the eaves
Fit these before or at the same time as blocking the original site, ideally close to it, so returning birds find the alternative. See our nest box guide for siting principles.
Common questions
Can I block the hole if the birds are out during the day?
No. If the nest is in use, blocking access is an offence regardless of whether birds happen to be inside at that moment — and you’d likely be sealing chicks in.
What if I’ve already blocked it and there are birds inside?
Reopen it immediately. Then seek advice — the RSPCA in England and Wales, or the Scottish SPCA in Scotland.
Can I remove an old nest in winter?
Generally yes, once the breeding season is over and the nest is genuinely unoccupied. House martin nests are worth leaving where possible, as they’re reused.
The noise is keeping me awake. Anything I can do?
Not lawfully, while the nest is active. Chick noise is loudest for a couple of weeks before fledging and then stops. Plan to close the gap in autumn.
Do I need to tell anyone?
Not routinely. But if you have swifts, local swift conservation groups are often keen to record sites — several regions maintain nest site registers.
Will they come back next year?
Very likely, particularly swifts and house martins, which show strong fidelity to specific nest sites. That’s exactly why proper repair in autumn matters if you need the gap closed.
Related guides
- When to put up a nest box (and exactly where to site it)
- When do garden birds nest in the UK?
- I’ve found a baby bird — what should I do?
- Black birds in your garden: crow, rook, jackdaw or something else?
Sources: Wildlife and Countryside Act 1981 (including Schedule 1); RSPB guidance on birds nesting in buildings; RSPB conservation status listings; RSPCA guidance on nesting birds.
This page carries no product links. It’s about a legal question, and this is general information rather than legal advice — for a specific situation, particularly one involving building work, seek advice from the RSPB or a qualified ecologist.
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