How do barbets excavate nest holes despite having bills that are not chisel-shaped?

Because the bill of a barbet is not chisel-tipped like that of a woodpecker, the process of excavating a nest cavity is a task that requires great effort. Consequently, barbets typically restrict their nesting to dead, well-rotted trees, which are easier to penetrate than living wood.1

While they lack the specialized wood-pecking anatomy of the Picidae family, both sexes of the barbet participate in the excavation of the cavity. In addition to using dead trees, some species may also burrow into the ground or into termite nests. Once a cavity is created, it often features a nearly round entrance that is small relative to the size of the bird, and the same site may be reused for several nesting seasons.12