One of my favorite greens in nature is the Green Heron- Butorides virescens. It is a small heron which makes its way around the marshes. I sometimes see them on my dock but they are most at home in the reedy marshes or fishing from submerged branches. Their coloration allows them to blend in easily.
They generally seem to have a short neck, as can be seen above. In fact, it is just carried tucked in until it it time to strike at which time you will see an impressive extension.
The are one of my favorite little birds to watch and photograph.