Birds keep nesting in my vents. How do I keep them out?

Vents are sheltered, dry and often warm, which is why birds pick them year after year. The lasting fix is a proper vent guard, made for that vent, that lets air through and keeps birds out. Fit it once the nest is empty and before the next nesting season. Do that and the yearly cycle usually stops.

If it happens every year, that is not bad luck. Many birds come back to sites that worked for them before, so an open vent gets reused until it is covered.

First, make sure it is empty

Watch the vent from a distance at dawn and dusk. Adults flying in and out, nest material going in or chicks calling mean the nest is in use. In many countries, nests in use are protected by law, so wait until the young have left. If you are not sure, ask your wildlife agency, council or a bird charity. Our answer on removing a bird’s nest covers the signs and the rules.

Never cover a vent with birds or chicks inside. They will be trapped, and you will have a dead nest in a duct.

The order to do it in

1. Clear the old nest. Gloves, and a mask if it is dusty. Wet droppings before you scrape, never sweep them dry. Bag it all. Pull out material from inside the duct as far as you safely can.
2. Check the vent still works. Extractor fans and tumble dryer vents should blow freely. A dryer vent clogged with nest and lint is a fire risk, so have a blocked one cleared properly.
3. Fit a guard made for that vent. For roof, soffit and gable vents, that is metal mesh fixed behind or over the opening. For extractor and dryer outlets, a cover with a flap or grille that still lets air out. Metal lasts longer than plastic, and birds cannot pull it loose.
4. Check the other gaps. Birds that lose one vent try the next spot: gaps under roof tiles and fascia boards, holes in soffits, behind gutters, outside light fittings. Our guide to sealing gaps covers the materials.
5. Do it between seasons. Late summer, autumn and winter, once nests are empty, is when to fit everything, so it is ready before birds start looking again.

Boiler flues and gas appliance vents: never block, cover or fit your own mesh to a flue or a vent for a gas, oil or solid fuel appliance. A blocked flue can let carbon monoxide into the home. Only fit a guard approved for that flue, by a qualified engineer. If a nest may be blocking one, stop using the appliance and call an engineer.

Will chicken wire do?

As a stopgap, perhaps. As a fix, not really. It sags, rusts and pulls away at the edges, and a determined bird will find the gap at the corner. Purpose-made metal vent guards and fine mesh are designed to fit tightly and keep the airflow the vent needs. If several vents are affected, buy matching guards for all of them, not just the ones with nests this year, as birds simply move along.

When to get someone in

Roof and gable vents usually mean ladders or roof work. If it is high up, or you are not confident on a ladder, a roofer or a bird control company can fit guards safely. Ask them to check for active nests first and to cover every vent of the same type. If you rent, write to your landlord: vents and roofs are usually the building’s side.

Spikes, netting and other humane deterrents for ledges and balconies are in the birds guide.