A great bittern (Botaurus stellaris) with his stretched body and beak, balances gracefully in the reeds in Zazari lake. This motionless posture offers the appropriate camouflage for the heron as it perfectly blends with the dense reeds habitat. The great bittern raises his body and at the same time observes with his peripheral vision the "threat". If the observer moves a few meters, the great bittern turns his body very slowly, always maintaining the same posture. It is the rarest heron of Greece and a rather solitary species which meets other individuals only during mating, between April and June. During the breeding season we also hear its famous baritone call. This strange call is heard up to five kilometers and consists of low frequency sounds that resemble the voice of an ox (hence the scientific name Botaurus) or even a drum or the sound that comes out when we blow into an empty bottle. A sound that has inspired legends about the "beast of the swamp" in different regions of Greece.