Together with the Great Tit and Blue Tit, the Pied Flycatcher is the most studied box-nesting bird in Sweden — an enormous body of the classic cavity-nester research, not least at Ottenby, is based on precisely this species. The right hole size and placement determine whether the box becomes attractive.
| Measurement | Value | |---|---| | Entrance hole | approx. 32 mm round (an oval hole or half-open front also works) | | Internal floor dimensions | approx. 12 × 12 cm | | Internal height | 15–20 cm | | Height of hole above floor | 12–17 cm | | Mounting height | 1.5–4 m |