Use by tits of nest boxes of different designs in pinewoods

Two experiments tested the preferences by tits in pinewoods for different nest box designs. Great, Blue and Coal Tits preferred deep boxes (≈ 19 cm from base to entrance lip) over shallow ones (≈ 9 cm). Crested `Tits preferred boxes that had been filled with sawdust and wood-shaving which they removed before nesting. The excavation of a fresh nest cavity each year perhaps ensures that nests are free of fleas for Crested Tits.