Great Blue Heron Ardea herodias
Version: 1.0 — Published March 4, 2020
Text last updated April 28, 2011
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Habitat in Breeding Range
Widespread and remarkably adaptable. During the breeding season, forages in wetlands, water bodies and water courses of all shapes and sizes, but can also be found occasionally in upland areas as well. Butler et al. (2000) identify the following as key foraging habitats: shallow coastal marine waters, coastal mangrove swamps, sea beaches, prairie, pasture and cultivated fields, aquacultural ponds, and residential and commercial sites where handouts or fish scraps can be found. In coastal Yucatan, species prefers freshwater systems (Ramo and Busto 1993), but in the Pacific Northwest it prefers seacoasts (Butler 1997). Several studies have observed a preference for areas of open water and estuarine wetlands (Butler 1997, Loegering and Anthony 1999, Cister and Galli 2002, Kelly et al. 2005), but one study in Mississippi found herons avoided open water areas (Custer et al. 2004). This variability in the literature attests to their adaptability in and the difficulty in generalizing about their habitat use.
Nests in trees, bushes, on the ground and on artificial structures (see Breeding: nest site), usually near water. Prefers to nest in vegetation on islands or in swamps, probably to avoid ground predators. Reported breeding at elevations up to 1,100 m in British Columbia (Campbell et al. 1990b), 610 m in Vermont (Laughlin and Kibbe 1985), and 1,500 m in Panama (Hancock and Kushlan 1984). Along the east coast of the U.S. (New Hampshire and New York), reported to avoid nesting near marine habitats (Spendelow and Patton 1988), favoring inland sites. However, farther north and south it nests near fresh and salt water.
Occidendalis herons found almost exclusively in shallow water marine habitats, particularly turtle grass (Thalassia testudinum) flats in open water or along shorelines; in Florida they use mangrove islands for nesting (Powell and Powell 1986).
See also Food Habits: microhabitat for foraging.
Habitat in Nonbreeding Range
Habitat in Migration
No information available, but habitats are probably similar to the breeding season.
Habitat in Overwintering Range
Little information. Mikuska et al. (1998) report that this species has the widest wintering distribution of any heron species in North America. These authors analyzed Christmas Bird Count data to determine key wintering areas for Great Blues, noting that local ground truthing will be required to field verify areas because the analysis used band recovery data. In addition, their dataset was limited, so it is likely that some areas that have importance were not well represented in the data. Nevertheless, the key areas for wintering Great Blue Herons they identified included the Dominican Republic, the US Midwest, the northeast and southwest coasts of Mexico, the northwest coast of mainland Mexico, southern inland waters of the Pacific Northwest and Central California.
In Oklahoma, the species is reported to avoid farm ponds with little emergent vegetation in favor of natural wetlands and riverbanks (Heitmeyer 1986). For non-migratory herons in British Columbia, individuals fly to estuaries (adult females) and nearby grasslands (juveniles) in autumn and winter when high tides and declining fish populations make foraging unprofitable on beaches (Butler 1997). Also in British Columbia, some adult males spend fall and winter on territories along river banks (Butler 1997). Great Blue herons forage occasionally in dry fields (Butler 1997). Along the east coast of the U.S., the species favors coastal marine habitats, especially salt marshes.