Advice from RSPB is that nestboxes are excellent substitutes for the holes found in old trees. In young woodlands and plantations, and in many parks and gardens there may be plenty of food for small birds but nowhere for hole-nesting birds to nest. Over 60 species are known to have used nestboxes. Regular residents include blue, great and coal tits, nuthatches, house and tree sparrows, starlings, spotted and pied flycatchers, robins, house martins, kestrels and tawny owls. Much depends on the type of the box, where it is located, and on its surroundings. In recent years, the fortunes of many birds have varied. For example, blue and great tits have prospered, while house sparrows and starlings have declined. If you want to provide a nest box, try, if possible, to target those birds that genuinely need help.