Bird behaviour at nestboxes

Tits are regularly seen hammering away at the entrance hole of a nestbox. This is probably a form of display by the male, rather than an attempt to enlarge the hole.

Later, the female will also peck vigorously: natural holes may have all the surrounding bark chipped away. This may help her to judge how soft the wood is and whether the hole will provide a safe, predator-proof home in which to raise her brood. Blue and great tits will also hammer at the inside of a box or nest hole, perhaps as a form of display.

Nuthatches leave tell-tale signs of their residence in a nestbox. They peck at the entrance hole, deliberately enlarging it. They then plaster the edges of the hole with mud, making sure the hole a perfect fit for their bodies.

Pied flycatchers are fast nest builders. They have been known to take over a nestbox in use by another bird, and build their own nest and lay eggs on top of a fresh clutch – or even live chicks – within days.

Many birds roost in nestboxes, especially during a cold winter night. These roosts are frequently communal with the birds packing together for extra warmth. The record number of birds found in one box is 61 wrens!