Does the entrance hole size really matter?

Yes — hole diameter is the main factor determining which species can use a box and which predators or competitors are excluded. A hole sized for a great tit (around 32 mm) is too small for a starling to enter, while a box built for starlings or larger species has a wider opening that smaller birds could use but that also admits more competitors.

When and where should a nest box be put up?

Late autumn or winter is ideal, giving birds time to find and investigate the box well before the breeding season begins, and some species even use boxes for winter roosting. Placement should avoid full afternoon sun (risk of overheating chicks), face away from prevailing wind and rain, and sit high enough to deter ground predators and cats.

Bird Atlas

Nest Box

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A nest box is an artificial cavity built to attract hole-nesting birds where natural tree cavities are scarce, from starling boxes to smaller tit and sparrow boxes.

What a nest box is and why it works

A nest box is an artificial cavity offered to birds that naturally nest in tree holes, filling a gap where old or decaying trees with existing cavities are scarce — commonly the case in managed forests, parks, and gardens where dead wood is regularly removed. The great tit and other cavity-nesting songbirds readily accept a well-placed box as a substitute for a natural hole, and decades of nest-box monitoring have made these species among the best-studied breeding birds in Europe as a direct result.

The Russian name for a nest box, skvorechnik, derives from the common starling (skvorets), reflecting the box's traditional association with attracting starlings specifically, though boxes of different dimensions suit a range of species from small tits to larger starlings and even owls or ducks in purpose-built larger designs.

Sizing and placement

Entrance hole diameter is the single most important design choice: it determines which species can physically enter and, just as importantly, which predators and larger competing species are excluded. A hole around 32 mm suits smaller tits while excluding starlings and larger competitors; a wider hole needed for starlings admits birds that would otherwise outcompete smaller species for the same box.

Placement matters almost as much as design. A box should avoid direct afternoon sun, which can overheat chicks in an enclosed space with limited ventilation, and should face away from the prevailing wind and driving rain. Mounting height of two to four meters, angled slightly downward to shed rain from the entrance, and a location away from easy access for cats or climbing predators all improve a box's chances of being used successfully. Putting boxes up in late autumn or winter — well ahead of the breeding season — gives birds time to discover and even roost in them before deciding to nest.