Green Backed Heron

The Green Heron (Butorides virescens) is a small heron of North and Central America. It was long considered conspecific with its sister species theStriated Heron (Butorides striata), and together they were called "Green-backed Heron". Birds of the nominate subspecies (no matter which taxonomicarrangement is preferred) are extremely rare vagrants to western Europe; individuals from the Pacific coast of North America may similarly stray as far as Hawaii.

Source: http://www.wikipedia.org/