Before covering nest boxes and how we can help birds nest, we will first cover natural nesting behaviours. Please note that all nesting birds are protected by law. Please read our ‘Legislation’ page for further information.

Natural nests

While nest boxes provide vital artificial cavities, the majority of British garden and woodland birds build natural nests within vegetation, tree structures, and building architecture. Understanding how and where birds naturally nest allows us to protect active broods and adapt our gardens to support them.

Natural nests and locations

Different birds have evolved different nesting strategies to conceal nests from predators and insulate chicks from wet and cold weather.

Classic cup nests in dense scrub and hedges

Species that use the cup nest design include thrushes (blackbirds & song thrushes), chaffinches, and dunnocks. Cup nests are sturdy, woven bowls constructed from twigs, moss, dry grasses, and animal hair. Song thrushes line the interior with a smooth, hard “plaster” made of mud, rotten wood, and saliva to make it waterproof. They are often built tucked into dense native hedges.

Low ground & scrub dwellers

Low ground and scrub nesters typically include wrens, robins, and willow warblers. Male wrens build several domed nests from moss, leaves, and lichen – tucked into low crevices, root balls, or dry stone walls. The female wren selects a nest, lines it with soft feathers, and lays her eggs. Robins build a completely different nest: open, messy cups of dead leaves and moss. Often tucked into grass tussocks, steep ditch banks, and low tree hollows. As these nests sit under 1m off the ground, they are prone to predation, disturbance by dogs, and lawn-mowing accidents.

Building nesters

Building nesters include house martins, swallows, and swifts. They build pellet by pellet using wet mud and bind them together using grass stems and saliva. House Martins construct enclosed cups under exterior eaves. Swallows build open, shallow mud bowls on internal beams inside open outbuildings and barns.

How to help naturally nesting birds

Helping nesting birds involves providing natural materials, preserving habitats, and removing seasonal hazards.

Natural materials

During March, April, and May, birds burn significant amounts of energy while gathering thousands of individual items. Consider implementing a mud structure. Keep a shallow patch of bare garden soil or pond margin wet and muddy. Put out small bundles of clean, chemical-free materials, such as raw sheep’s wool and dried moss. Lastly, consider putting untreated pet hair (dog/cat) as it is an excellent insulator for tit nests. Only use pet hair if the animal has not been treated with spot-on flea or tick chemicals within the last 4 weeks.

Protect natural nest sites

Avoid pruning or heavy shaping of hedges, thick shrubs, and climbing ivy during the breeding season (1st March – 31st August). Trim hedges between November and February. If an urgent fence repair or path clearance is unavoidable between March and August, carry out an exhaustive check of the target vegetation first. Watch for adult birds repeatedly carrying nesting material or food into the same patch of vegetation.

Managing garden hazards

If you have an outdoor cat, fit them with a quick-release collar carrying a bell or a brightly coloured collar to reduce hunting efficiency. Keep cats indoors during peak fledgling hours (dawn and dusk from May to July). Never spray insecticides or bug killers on garden plants. For example, tits need up to 100 caterpillars a day per chick. Lastly, apply external anti-collision stickers to windows to prevent window strikes.

Artificial nesting opportunities

Installing artificial nest boxes replicates natural cavities that are increasingly scarce in modern gardens and managed landscapes. Choosing the right box design and entrance size ensures target species can enter while excluding competitors and predators.

Hole-nesting boxes

Small entrance hole (25 mm – 28 mm): this box would be suitable for blue tits, coal tits, and marsh tits (UK-red listed species). A box size of 25mm would exclude competitors, such as great tits. However, great tits can be accommodated by using a 28mm entrance hole, whilst excluding starlings.
Standard entrance hole (32mm): targets species such as house sparrows, great tits, and nuthatches. This box is the classic general-purpose garden box.
Colonial boxes (sparrow terraces): house sparrows nest in loose colonies. Provide a multi-chamber terrace or group two to three separate 32mm boxes.

All three of these box types can be fitted with a metal predator-reinforcement plate to stop squirrels and great spotted woodpeckers from enlarging the entrance.

Open-fronted nest boxes

Open-fronted nest boxes often support robins, wrens, dunnocks, and spotted flycatchers. The upper front panel is 50% open, with a lower retaining lip to hold the nest cup. As open-fronted boxes are visually exposed, they must be hidden with dense, thorny vegetation to shield eggs and chicks from corvids and cats.

Specialist nest boxes

Swift bricks and boxes target the common swift. Fitted with a narrow oblong slot. Swifts require an uninterrupted, clear flight drop of at least 4 to 5 metres directly beneath the entrance hole.
House martin nest cups are pre-moulded cups that are installed directly beneath exterior soffits.

Sitting and Installation Standards

Aspect: boxes should be mounted facing North and North-East to shelter the entrance from rain and prevent lethal overheating.
Mounting height: hole-nesting boxes should be mounted between 2 and 4 metres high on a mature tree trunk, outbuilding, or wall with a clear flight line to the hole. Open-front boxes should be mounted between 1.5 and 2.5 metres and should be tucked into dense vegetation.
Box angle: mount the box vertically or tilted slightly forward so rainwater runs off the sloping roof rather than running back into the entrance hole.