- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
Regular summer visitant and migrant; formerly bred in Minnesota from 1971 to 1986. The Snowy Egret was a very rare species during the Minnesota Breeding Bird Atlas (MNBBA).
The primary breeding range of the Snowy Egret is along the Atlantic and Gulf coastal areas, with inland fingers to southern Kansas and up the Mississippi River to southeast Missouri. In the west the Snowy Egret breeds locally in many states from Arizona and California north to Oregon and Montana. Disjunct breeding populations are present in eastern South Dakota (Tallman et al. 2002) and in the Great Lakes at Green Bay, Lake Michigan, and West Sister Island in western Lake Erie (Cutright et al. 2006; Peterjohn and Rice 1991; Rodewald et al. 2016). It is a breeder and permanent resident in many parts of Mexico, Central America, the Caribbean, and much of South America. In North America some of the highest breeding densities are found in southern California and the Gulf coast of Louisiana (Figure 1).
Designated a Species of High Concern by the North American Waterbird Conservation Plan; assigned a Continental Concern Score of 7/20 by Partners in Flight.
Northern breeding birds winter along the Gulf coast, in Mexico, and on the Caribbean Islands. During the migration period, wandering or dispersing birds can be found most anywhere in the United States to the southernmost Canadian provinces.
Feeds primarily on aquatic animals such as frogs, crayfish, small reptiles, fish, worms, and insects in shallow waters. The Snowy Egret employs a wide variety of foraging strategies, including actively running to flush prey, hopping, foot stirring, or standing still and stalking prey. It feeds in large groups with other Snowy Egrets and other waterbirds.
A platform nest of sticks constructed in a tree or in dense shrubs. Snowy Egrets nest in large multispecies colonies, occupying a core site with conspecifics within the larger colony. The birds select spots within the colony that can be defended from adjacent birds.
This elegant egret, with its bright yellow feet, was not known in Minnesota when Roberts wrote his two-volume treatise on Minnesota birds in 1932. He wrote, “If the Snowy Egret ever occurred at all in Minnesota it was as a very rare straggler many years ago when Egrets were much more abundant than in recent years.” He noted, however, that a mounted bird, shot in April 1884 at Heron Lake, was seen on display there by J. W. Preston in 1885 (Roberts 1932). The first documented records in the state were reported in 1950 in Faribault County (Longley 1950), and in 1951 at Lake Traverse, Traverse County (Enstrom and Bardon 1986).
Snowy Egret records slowly increased in the 1960s and the 1970s, prompting the Minnesota Ornithologists’ Union (MOU) to change its status category from “casual” to “rare regular” in 1983. Breeding was discovered at three locations during this time of expansion: (1) Lake Johanna, Pope County, in 1971; (2) Big Stone National Wildlife Refuge (NWR), Lac qui Parle County, in 1977, 1978, 1980, and 1981; and (3) Agassiz NWR, Marshall County, in 1986. The first two sites are large, multispecies rookeries comprised primarily of Great Blue Herons, Great Egrets, and Black-crowned Night-Herons; the Snowy Egret observations were of a few nests at each site (2–12). Surveying these multispecies colonies in remote or not easily accessible locations is difficult and not done by casual observations. These colonies of hundreds or even thousands of birds are chaotic, and much patient watching is necessary to determine which species have nests where, especially for the small herons with small numbers. The nesting records in the late 1970s and early 1980s were reported by federal and state professionals either at national wildlife refuges or through the Minnesota Department of Natural Resources (MNDNR), Nongame Wildlife Program.
Summer observations of Snowy Egrets in Minnesota have steadily increased from the 1990s into the 21st century, but no other breeding records have been documented. Nevertheless, it should not be concluded that this egret has not continued to nest in small numbers. The MOU’s seasonal report observations from 1985 to 2015 consistently show clusters of observations in the counties where there are national wildlife refuges or large lakes with multispecies rookeries, such as Pelican Lake, Grant County, and Long Lake, Kandiyohi County. There also is a cluster of reports in the Twin Cities (Anoka, Hennepin, and Ramsey Counties), but it is hard to tell if they are the result of many observers or possible breeding at sites like the Minnesota Valley NWR, Carlos Avery Wildlife Management Area, and the Pig’s Eye Island Heron Rookery Scientific and Natural Area. Since the early 1980s, statewide colonial waterbird surveys have been limited to 5 aerial surveys of known Double-crested Cormorant and American White Pelican colonies conducted from 2004/2005 to 2015 (Hamilton and Cuthbert 2016). Although the colonies surveyed include most of the state’s largest mixed-species waterbird colonies, Snowy Egrets have not been reported. Identifying rare species that often nest lower in the canopy of colonies that contain hundreds of nests is extremely difficult from the air. As a result, periodic ground surveys are especially important for monitoring the breeding status of species like the Snowy Egret.
Because the records listed above are the only breeding records known, citations are provided: Lake Johanna, 1971 (1 pair, Hitman 1972); Big Stone NWR 1977 (about 10 nests, Ehlers 1977), 1978 (12 nests, Green 1979), 1980 (about 12 birds, Guertin and Pfannmuller 1985), 1981 (about 2 birds, Guertin and Pfannmuller 1985); and Agassiz NWR 1986 (1 nest, Mattsson 1986). There is one other very large and persistent multispecies colony, in Grant County on Pelican Lake, where Egret Island is a MNDNR Scientific and Natural Area. The list of species recorded on the island includes Snowy Egret, but no specific information has been published.
Snowy Egrets are regularly found in the state from mid-April through mid-October. Many of these birds are migrants or dispersing or wandering birds from other colonies. Almost all the records in the MOU seasonal reports are from the Prairie Parkland and Eastern Broadleaf Forest Provinces, the latter considerably fragmented by development and agriculture. Except for a few vagrants from the Duluth estuary (2000, 2006, 2007), the only other reports from the Laurentian Mixed Forest Province are single vagrants in Hubbard (2008), Lake (1984), and northern St. Louis (1985) Counties. Most observations reported are from the spring, which is the prime time for bird watching. There have been a couple of notable large influxes of Snowy Egrets in recent years. One was in 2000, which was well documented (Tustison 2001), and another was in 2004 (Budde et al. 2004). In the fall most birds are gone by the end of September.
During the MNBBA, participants reported only 3 Snowy Egret records from 3 of the surveyed atlas blocks (Figure 2 and Table 1). A “probable” observation (coded “N”) from the colony at Pelican Lake, Grant County, was recorded with the following notes: “8 adults seen foraging in stream connecting Melby Lake and Pelican Lake; adults fly out to island after foraging where huge heronry exists but nest not visible at this distance; strongly suspect breeding with other herons and egrets.” One “possible” record was reported from the Paynesville sewage treatment plant, Stearns County (“single adult bird with plume”), and 1 “observed” record was reported from southern Hennepin County (“2 birds seen”). During the atlas years, there were a number of summer observations of Snowy Egrets in the MOU database that were not submitted to the atlas but were from counties where known multiple-species colonies exist: Big Stone, Lac qui Parle, and Kandiyohi.
*Note that the definition of confirmed nesting of a species is different for Breeding Bird Atlas projects, including the definition used by the Minnesota Breeding Bird Atlas, compared with a more restrictive definition used by the Minnesota Ornithologists’ Union. For details see the Data Methods Section.