Great Blue Heron, Ardea herodias

Great Blue Heron, Ardea herodias herodias, Adult, Blue Morph. Photograph taken in the coastal area of Yavaros, Sonora, December 2018. Photograph and identification courtesy of David F Smith, Alamos, Sonora.

Great Blue Heron, Ardea herodias herodias, Adult, Blue Morph. Photograph taken in the greater Los Cabos area, Baja California Sur, February 2017. Photograph courtesy of Carol Snow, Del Mar, California.

Great Blue Heron, Ardea herodias occidentalis, White Morph. Photograph taken within the Everglades of Southwest Florida, February 2019. Photograph courtesy of Carol Snow, Del Mar, California.

Great Blue Heron, Ardea herodias wardi, Adults, Blue Morph. Photograph taken in the greater Puerto Adolfo Lopez Mateos, Baja California Sur, November 2016.

Great Blue Heron, Ardea herodias wardi, Adults, Blue Morph. Photograph taken in within the Wakodahatchee Wetlands, Delray Beach, Florida, February  2023. Photograph and identification courtesy of Faith Hubsch, Fort Lauderdale, Florida.

Great Blue Heron, Ardea herodias wardi, Adults, Blue Morph. Photograph taken within the Everglades National Park, South Florida, April 2020. Photograph and identification courtesy of Faith Hubsch, Fort Lauderdale, Florida.

Great Blue Heron, Ardea herodias wardi, Adult, Blue Morph. Photograph taken with the rocky shoreline of the greater Bahía de los Ángeles area, Baja California, January 2022.  Photograph  courtesy of George Flicker, Bahía de los Ángeles. Identification courtesy of Mary & George Flicker, Bahía de los Ángeles.

Great Blue Heron, Ardea herodias wardi, Blue Morph. Photograph taken within the Everglades of Southwest Florida, February 2019. Photograph courtesy of Carol Snow, Del Mar, California.

Great Blue Heron, Ardea herodias wardi, Blue Morph. Birds photographed in the Parque National Huatulco, Huatulco, Oaxaca, March 2021. Photographs and identification courtesy of Marina Sutormina, Stockholm, Sweden.

Background and Identification

The Great Blue Heron, Ardea herodias herodias, Ardea herodias occidentalis and Ardea herodias wardi are three of five subspecies of Great Blue Heron, all three of which are found in Mexico. They are a member of the Ardeidae Family of Herons, Egrets and Bitterns. There are twelve members of the Ardea Genus. The Great White Heron is known in Mexico as garza azulada.

The Great Blue Heron is the largest heron in North America. The sexes are similar in appearance, but the females are slightly smaller in stature. The blue morph subspecies (Herodius Group) has gray underparts, a fore-neck streaked with white, black and rust brown. The head is mostly white with a wide blue stripe running above the eyes to the back of the head. They have a long neck and long legs. The adults have a long body and occipital plumes that are absent in juveniles. Their wings are long and rounded. They have a long, tapered yellow bill, yellow eyes and brown to greenish legs and a short tail. The adults have a white crown; the juveniles have a solid gray crown. The white morph subspecies (Occidentalis Group) has totally white plumage and known as the Great White Heron.

Habitat and Geographical Range

The Great Blue Heron is one of the most widespread and adaptable wading birds in North America. They are found in both marine coastal and freshwater habitats. They are known primarily as a shoreline coastal wader that can also be found in the interior at elevations up to 2,500 m (8,200 feet). They are diurnal feeders that feed as solitary individuals or in small groups with other species of colonial waterbirds in shallow coastal marine waters, coastal mangrove swamps, sea beaches, prairie, pasture and cultivated fields, and aquacultural ponds. The occidentalis subspecies prefers freshwater systems. Inland birds also consume rodents and other animals. They consume amphibians, invertebrates, mammals and reptiles. Their nests are preyed upon by bald eagles, common ravens, crows, hawks and vultures as well-as bears, racoons, and snakes with first year mortality rates of 70%. They are also disturbed by human activity. They nest in mixed-species assemblages of colonial waterbird in trees, bushes, on the ground and on artificial structures usually near water. They prefer to nest in vegetation on islands or in swamps, to avoid ground predators. Colonies can reach several hundred pairs. They have life spans of up to twenty-three years.

The Great Blue Heron is found throughout Mexico. They are both migratory and non-migratory. The herodias subspecies, found in eastern Mexico south to Tabasco, and the wardi subspecies, found in northwest Mexico south to Sinaloa, make seasonal migrations to warmer climates for wintering. The occidentalis subspecies found in the Yucatán are non-migratory.

Common Misidentifications

The Great Blue Heron is unlikely to be confused with any other regularly occurring North American bird.

Conservation Status

From a conservation perspective the Great Blue Heron is currently considered to be of Least Concern with stable, widely distributed populations. There long-term survival is threatened by destruction and degradation of wetland habitat that destroys nesting environments and feeding areas.