The herons are long-legged freshwater and coastal birds, with 64 recognised species, some of which are referred to as egrets or bitterns rather than herons. Although herons resemble birds in some other families, such as the storks, ibises, spoonbills, and cranes, they differ from these in flying with their necks retracted, not outstretched. They are also one of the bird groups that have powder down. Some members of this group nest colonially in trees, while others, notably the bitterns, use reed beds. The herons are medium- to large-sized birds with long legs and necks. The necks are able to kink in an S-shape, due to the modified shape of the cervical vertebrae, of which they have 20–21. The neck is able to retract and extend and is retracted during flight, unlike most other long-necked birds. The neck is longer in the day herons than the night herons and bitterns. The legs are long and strong and in almost every species are unfeathered from the lower part of the tibia (the exception is the zigzag heron). In flight, the legs and feet are held backwards. The feet of herons have long, thin toes, with three forward-pointing ones and one pointing backwards.
Info source: https://en.wikipedia.org/wiki/Heron
