The Eurasian Bittern is one of the most endangered species in most parts of Europe. A member of the heron family, it needs wetlands with large reedbeds.
The Bittern has a very strange sound. Visit the RSPB Site about the Bittern to listen to its call.

On my trip to Neusiedler See Nationalpark (Eastern Austria) last week I was finally able to see one of those amazing birds. For 3 days we were only able to hear them (even from the hotel during the night). But on the fourth day we finally were lucky. We saw four of them. That one on the photograph came pretty close to our car after we waited silently. It was perfect to get a shot with the my 500mm telephoto lens (and 1.4x converter).
I hope you enjoy the picture. More pictures from that trip will follow once I have worked myself through the more than 2.000 pictures I took during that trip.