Great Egret (Ardea alba)

Photo by Jack Bartholmai Great Egret by Jack BartholmaiGreat Egret distribution map


Population Information

The Federal BBS information can be obtained at by clicking on Trend Estimates and selecting the species in question. All estimates are for time period (1966-2005).

Life History

Habitat Selection

The Great Egret nests in colonies ranging in size from several pairs to thousands of pairs, often in association with Great Blue Herons (Fruth 1988). Foraging habitat can dictate the size and location of breeding colonies (Fruth 1988, Custer et al. 2004). For instance, the Upper Mississippi River floodplain habitats provide abundant, shallow backwater habitats for foraging (i.e., sloughs, shallow lakes, and ponds downstream of a lock and dam) and support 4-7 nearby colonies of 100-300 pairs (Nelson and Wlosinski 1999, Custer et al. 2004). Elsewhere Great Egrets forage in stream and river edges, tidal pools, drainage ditches, and ponds used for commercial fish production (McCrimmon et al. 2001). Distances traveled from colony sites to foraging areas varies geographically but in Wisconsin has not exceeded 35 km (Fruth 1988).

Habitat Availability

Wisconsin is on the extreme northern edge of the Great Egret breeding range (McCrimmon et al. 2001) where it is considered an uncommon summer resident in the west, south, and east and rare in the central part of the state (Robbins 1991). Horicon Marsh/Lake Winnebago wetlands and the Mississippi River floodplain forests provide suitable colony sites in most years. However, the primary colony site (i.e., Four Mile Island) at Horicon Marsh was destroyed during a windstorm in 1998 and no longer supports a nesting colony (Volkert 2006). The widespread loss of floodplain forests has reduced the amount of suitable nest sites in the state. Although bottomland hardwood and other floodplain forests have fared better than many of Wisconsin’s native habitats, it is estimated that only 8% of presettlement floodplain forest remains in moderate to high quality condition (Mossman 1988). Invasive plant species, particularly reed canary grass, may impede regeneration in floodplain forests and development pressures also threaten remaining stands (WDNR 2005). The loss and degradation of wetland ecosystems within the state also impacts this species by reducing the quality and quantity of feeding sites. At existing foraging habitat, pollution and toxic contamination may reduce necessary food resources and thereby render nearby colony sites unsuitable (Fruth 1988).

Population Concerns

Historically, the Great Egret was considered to be a common species within appropriate habitats of Wisconsin (Kumlien and Hollister 1903, cited in Fruth 1988). Plume hunting in the late nineteenth century decimated Great Egret populations throughout North America and resulted in the extirpation of many local populations. The Wisconsin population declined precipitously during this era, with the last breeding attempt occurring in 1886. Protection efforts in the early twentieth century led to a rapid population recovery and Great Egrets were again breeding in Wisconsin by 1939 (Fruth 1988). Since that time, the number of nesting colonies statewide has fluctuated from as few as five to as many as ten during the recent Breeding Bird Atlas work; however, only two of the Atlas sites contained >10 pairs (Volkert 2006). Both the species’ rarity and its colonial nesting behavior make it difficult to determine its population status in the state. Wisconsin Breeding Bird Survey data suggest a non-significant population decline, but Wisconsin Checklist Project data indicate a significant increase in the state population (Sauer et al. 2005, Rolley 2005). The inconsistency of these results highlights the need for a targeted long-term monitoring program for this and other colonial waterbird species. Elsewhere in its range, the Great Egret appears to be experiencing a significant population increase (Sauer et al. 2005). 

Reductions in the quantity and quality of foraging and nesting habitats may be the primary factors limiting Great Egret populations (McCrimmon et al. 2001, Custer et al. 2004). Logging of floodplain forests, draining of wetland complexes, and contamination and pollution of extant wetlands have contributed to the widespread habitat loss and degradation.  

Recommended Management

An inter-agency partnership of state and federal agencies, private and non-profit conservation partners is needed to determine common goals and strategies for Great Egrets and other colonial waterbirds along the Upper Mississippi River and throughout the state (WDNR 2005). The protection and restoration of wetland complexes on public and private lands is of primary importance in managing this species. For private landowners, managers should develop information materials for enhancing/restoring their properties for Great Egrets and other herons (Fruth 1988). Protecting existing colony sites is essential to maintaining colonial waterbird populations in the state, including the Great Egret, Snowy Egret, and Black-crowned Night-Heron. At existing colony sites managers should: (1) institute protection measures for nearby foraging areas; (2) maintain water depths of foraging areas <28 cm; (3) reduce or eliminate the discharge of chemical contaminants; (4) reduce or eliminate human disturbances; (5) experiment with techniques to promote tree regeneration and to test the effectiveness of artificial nesting platforms; and (6) determine and implement measures to control predators at colony sites (McCrimmon et al. 2001, Custer et al. 2004, WDNR 2005). Although protection of existing colonies is essential, it is equally important to protect apparently potential habitat for colony expansion and colonization of new sites. Conservation efforts for this species should be focused in the following Wisconsin ecological landscapes: Central Lake Michigan, Northern Lake Michigan, and Western Coulee and Ridges (WDNR 2005).

Research Needs

More study is needed on the management techniques required to create, restore, or improve Great Egret nesting and foraging habitat in Wisconsin. A statewide inventory of suitable nesting and foraging habitat would better guide future conservation efforts. A long-term monitoring program for Great Egrets and other colonial waterbirds of Wisconsin is urgently needed and should evaluate population dynamics, food resource use, health and longevity of nesting and feeding sites, habitat productivity, and contaminant levels and effects (Fruth 1988). Study of a color-banded population could aid in studies of mortality and migration movements, survivorship, and other demographics. Researchers should continue to monitor and assess the effects of chemical contamination on Great Egrets and other wading birds (McCrimmon et al. 2001).  

Information Sources


Contact Information

Kreitinger, K., Y. Steele and A. Paulios, editors. 2013.
The Wisconsin All-bird Conservation Plan, Version 2.0. Wisconsin Bird Conservation Initiative.
Wisconsin Department of Natural Resources. Madison, WI.

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