The Hoopoe is a medium sized bird, 25–32 cm (9.8-12.6 in) long, with a 44–48 cm (17.3–19 in) wingspan weighing 46-89 g (1.6-3.1 oz). The species is highly distinctive, with a long, thin tapering bill that is black with a fawn base. The strengthened musculature of the head allows the bill to be opened when probing inside the soil. The hoopoe has broad and rounded wings capable of strong flight; these are larger in the northern migratory subspecies. The Hoopoe has a characteristic undulating flight, which is like that of a giant butterfly, caused by the wings half closing at the end of each beat or short sequence of beats.
The song is a trisyllabic "oop-oop-oop", which gives rise to its English and scientific names.From Wikipedia.