The great crested grebe (Podiceps cristatus) is a member of the grebe family of water birds noted for its elaborate mating display.The great crested grebe is the largest member of the grebe family found in the Old World, with some larger species residing in the Americas. It is an excellent swimmer and diver, and pursues its fish prey underwater. The adults are unmistakable in summer with head and neck decorations. (Wiki)