Diagnosis: Green Herons have a very short and stocky body build. Their bill is sharp, pointy, and dark in coloration. Similar to most heron species, they have a very long neck, but usually do not keep it elongated, instead holding it tight with the body. Whereas most other herons have long legs, the Green Heron has very short yellow legs. The adults adorn a shiny greenish black colored head with black crest, and a rust colored neck. The wings are a grey-black that turn to either a blue or green color, and their underside is grey. Males are slightly larger than females, and are also more brightly colored, more so during the breeding season. Coloration of the juvenile is different and quite dull from that of an adult; the sides of the head, neck, and underbelly are streaked with white and brown, and they have greenish-yellow colored legs and bill. Hatchlings are covered in light grey-white down. On average the adult birds are about 45 cm in length, and weigh around 175 g, which is about the size of a large crow.

http://ninnescahlife.wichita.edu/node/561