Nestbox buying guide: Choose the right design

Nestbox-using species have different requirements. Find out which box will attract which birds.

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Nestbox blue tit

Blue tit at a nestbox © James Gallagher

 

SMALL BOXES WITH HOLES

To attract blue and great tits, the BTO advises placing your nestbox between 1m and 5m above the ground. However, coal tits prefer a box no more than 1m high. A house sparrow will look for a box at least 2m high, whereas a nuthatch prefers a box at least 3m high. Make sure that foliage is not obscuring the entrance hole so that birds have a clear view outside and can avoid predators.

25mm hole Coal tit, blue tit, marsh tit

28mm hole Great tit

32mm hole House sparrow, nuthatch

 

SMALL OPEN-FRONTED BOXES

Birds that use small open-fronted boxes are prone to predation when they’re sitting on eggs. So put the box high enough to deter cats, and ensure that thick vegetation is growing across the front of the box for additional protection. The standard design uses the 100mm front panel.

60mm high at front Spotted flycatcher

100mm high at front Robin, pied wagtail

140mm at front Wren

 

MEDIUM BOXES WITH HOLES

These boxes are designed to attract starlings and great spotted woodpeckers, which favour sites over 2.5m high and over 3m high respectively. In areas where there are fewer alternative nest sites, such as dead trees and pan-tile or corrugated roofs, these boxes can be more successful at attracting starlings.

Oval-shaped hole Swift

45mm hole Starling

50mm hole Great spotted woodpecker

 

NESTING IN COLONIES

House sparrows, house martins, swifts and starlings prefer to nest in loose colonies high up in the eaves. Space out two or three nestboxes on the same side of your house.

 

NATURAL NEST SITES

Many garden birds will nest inside hollow trunks or cavities in rotten branches, but others prefer to make their own nest among dense foliage. Plants such as holly, whitebeam, hawthorn, blackthorn, firethorn and cotoneaster offer great natural cover – avoid trimming branches until pairs have finished nesting. Climbers such as Virginia creeper, honeysuckle, ivy and clematis also provide ideal nest sites.

 

BUYING GUIDE

A nestbox should be constructed from an insulating material, such as durable cedar, oak or beechwood – don’t choose one that is made from plastic, ceramic or corrosive materials.

The wood of the nestbox should ideally be 19mm thick (no less than 15mm) and the internal floor area should be at least 130cm² to give parent birds enough room to incubate their eggs and brood the young. Remember too that the diameter of the nestbox hole should be suitable for the type of species you hope to attract.

A good nestbox should be accessible and not too high so you can clean it out easily. Wooden boxes can be treated on the outside with a preservative provided that it is non-toxic and water-based.

 

Find out more about the BTO’s National Nest Box Week.

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