Lena Chow sent in a video clip of a Coppersmith Barbet (Megalaima haemacephala) excavating a nest hole on a branch of a rotting tree (above). Note the abundance of bracket fungi that are involved in the degradation of this rotting branch (below).
Barbets are one of a few genera of birds that are capable of excavating their nesting holes. Usually excavating takes place in rotting or dead wood as it is soft and easily excavated. There is a downside to this as rotting branches have the tendency to break or topple over.
Usually, one bird does the excavating while the mate hovers around keeping watch. The site may be the focal point of courtship rituals and changing shift may be part of this.