96-119 cm, sexes similar. Grey with black and white head and the tips of the wings black. It flies with outstretched neck, unlike herons which fly with it folded. Present during migration and in particular from late February to April, more scarce and irregular in the autumn. It winters with very variable contingencies. It forms imposing flocks that fly in formation online making the characteristic and powerful call that gives it its Latin name. It sleeps in the coastal marshes but feeds in fields. It used to nest in the wetlands of the northern Adriatic until the early decades of the twentieth century.