The bittern is most often to be found among reed beds in the shallow waters of flatland lakes, especially those of central Sweden. It keeps out of sight amidst the dense growth of reeds. It is there that the bittern finds its food supply of fish, frogs and insects. It is also where it builds its nest and raises its young.
The bittern has a special call which sounds like the noise made by blowing across the opening of an empty bottle – a very deep, abrupt and muffled tone. When the air is still, the sound can be heard up to five kilometres away.
This is the call by which the male announces possession of his territory. It lends a mystical air to the flatland lakes during the damp nights of early summer.
When alarmed by intruders, the bittern assumes a remarkable position. Standing completely still, it stretches its head and bill straight up toward the sky, blending uncannily into the forest of reeds. The camouflage effect is heightened by the streaked, yellow-brown plumage.