Generally quite common and conspicuous in wetland habitats from marshes and tidal flats to small ponds, ditches, and wet fields; nests colonially in tall trees. Mainly seen as singles or in small groups, standing quietly in or at the edge of water, less often hunting in fields. Plumage mostly gray overall, with paler neck; adult has white crown, black eyebrows, and black shoulder patch. Like other herons and egrets, flies with neck pulled in to form a bulge.
Grey herons are very hardy and generally adapt well to new environments. However, for continuous habitation, grey heron populations require locations that experience at least four months of warm weather. These warmer periods are necessary for laying eggs and early development of chicks. Grey herons also require some type of shallow body of water, which they use as their primary forage sites. These bodies of water may include saltwater or brackish inlets and estuaries, freshwater rivers, streams, lakes, or marshes, and even aquacultures used in fish farming. Roosting requirements vary by geographic region; however, many individuals choose to roost in branches at or near the top of taller trees. If trees are unavailable, grey herons may roost in dense brush or undergrowth.