Like the beak in general in birds have many other functions, so they use it for display, nest construction, singing, thermoregulation in some cases like toucans or like hornbills ...
We saw more lilac-breasted rollers as well as a flock of enormous southern ground-hornbills, spied a brown-hooded (and orange-beaked) kingfisher and heard the cry of a grey go-away bird just in time to spot it.