The Red-crowned Barbet (Megalaima rafflesii) was actively digging a nesting hole in a dead tree trunk at Lower Peirce Reservoir in July 2016 when Kumchun Chan documented it on video (below).
Such excavation is time consuming and energy demanding. The barbet, a primary cavity nester, is seen vigorously pounding into the round opening to emerge every now and then with a beak-full of wood chips that it discard with a vigorous flick of its head. Note that there is another cavity lower down but the barbet prefers to dig a new one. Being a primary cavity nester it only nests in newly constructed cavities.
Other primary cavity nesters include kingfishers and woodpeckers. These birds have strong bills that have evolved into excellent building tools.
Dollarbirds and hornbills are secondary cavity nesters, making use of disused cavities of even hijacking other birds’ nests. The disadvantage of old cavities is that it is unsanitary, sometimes leading to unhealthy chicks.
The advantage of nesting in cavities as compared to nesting in the open is protection from predators. Such nests also provide shelter from the elements.
25th July 2016