- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A summer visitant and regular migrant; formerly bred in Minnesota from 1970 to 1992. The Cattle Egret was a very rare species during the Minnesota Breeding Bird Atlas (MNBBA).
Primarily found in the southern United States from North Carolina to New Mexico and California with populations expanding north as far as southern Canada. In the United States, nesting has been confirmed in all contiguous states except Montana, New Hampshire, Washington, and West Virginia. Cattle Egrets also occur in South America, Mexico, Central America, and the West Indies as well as in many other parts of the world including Africa, Asia, western Europe, and Australia. Its range expansion has been described as “one of the most rapid and wide reaching natural expansions of any bird species” (Wikipedia). Highest breeding densities are found in the core of its breeding range in the southern states, especially Florida, Louisiana, Texas, and southern Oklahoma (Figure 1).
Assigned a Continental Concern Score of 9/20 by Partners in Flight and designated a species Not Currently at Risk by the North American Waterbird Conservation Plan.
A strongly migratory species, during the winter the Cattle Egret leaves the northern part of the breeding range and is found around the Caribbean Islands, Mexico, Central America, and northern South America. Juveniles disperse widely, often long distances and in random directions, and rarely return to their natal colony to breed.
The species is noted for its association with feeding cattle, which flush their desired prey, such as grasshoppers and crickets. Food is mostly insects but also frogs, crayfish, bird eggs, and nestlings. Like all herons and egrets, foraging during the breeding season can be up to 15 to 30 km from the colony but usually is 3 to 10 km (Telfair 2006). Cattle egrets usually forage in small to large flocks in upland foraging sites on lawns, large fields, and pastures and along watercourses.
A platform or shallow bowl constructed of sticks and placed in trees or shrubs; may use abandoned nests of other species. This colonial nesting heron is gregarious at all seasons. Cattle Egrets nest and roost in colonies with other herons. They may begin nesting about 3 weeks later than native herons and nest 7 to 9 weeks longer (Telfair 2006).
The Cattle Egret is an Old World species that arrived on the eastern coast of South America about 1877, presumably having flown across the Atlantic Ocean from Africa. Its dispersal tendencies are remarkable, and even now it is regularly seen at sea (Telfair 2006). It originally was native to the tropical and subtropical areas of Africa and Asia and expanded its range to the northern Mediterranean in Spain and Portugal at about the same time as it crossed the ocean to South America. It first arrived in North America in Florida in 1941, bred there in 1953, and rapidly spread throughout this continent, both east and west, to the southern Canadian provinces.
Obviously, the Cattle Egret was not part of the avifauna in Minnesota when Roberts wrote his book in 1932. The first report of the species was in June 1959 in Pope County (Hanna 1959), which is the same county in western Minnesota where it was later found nesting. There were 9 more records from 1961 to 1970, mostly in southeastern counties and the Twin Cities but 2 in western Minnesota (Lac qui Parle County in 1969 and Stevens County in 1970). On August 21, 1970, a flock of 8 was spotted in northern Grant County (Moos 1971). All observations in western counties were in areas where there are large multispecies heronries, where the Cattle Egret was subsequently found nesting. The documented breeding records are from (1) Lake Johanna, Pope County, in 1971 (Hitman 1972), 1984 (Hendrickson and Eckert 1985; Guertin and Pfannmuller 1985), and 1985 (Wilson and Shedd 1986); (2) Pelican Lake, Grant County, in 1970 (Hitman 1972), 1971 (Eckert 1973), 1973 (Wyatt 1973), 1985 (Wilson and Shedd 1986), and 1986 (Shedd and Wilson 1987); (3) Long Lake, Kandiyohi County, in 1984 (Guertin and Pfannmuller 1985); (4) Big Stone National Wildlife Refuge (NWR), Lac qui Parle County, in 1977 (Eckert 1978) and 1978 (Green 1979); and (5) Thief Lake Wildlife Management Area (WMA), Marshall County, in 1992 (Wiens 1993; Minnesota Biological Survey). During the time of documented nesting, the first Minnesota specimen of the Cattle Egret was collected in November 1975 in Faribault County (Zink and Frye 1977).
In summary, Cattle Egrets have nested in three large heronries (Lake Johanna, Pope County, 3 years; Long Lake, Kandiyohi County, 1 year; Pelican Lake, Grant County, 4 years) and in two wildlife areas (Big Stone NWR, Lac qui Parle County, 2 years; Thief Lake WMA, Marshall County, 1 year). The time span of these documented breeding records is 1971 to 1992. There have not been any nesting records since then, although there have been yearly summer observations in subsequent years (1993–2014). Many of these observations have come from the same counties and from many other counties in the Prairie Parkland Province as well as some in the Eastern Broadleaf Forest Province. As is the case for two other small herons, the Snowy Egret and Little Blue Heron, which were first recorded nesting in the state during this same time frame, it is not clear if the absence of nesting records is due to a lack of intensive, ground surveys of colonies or to the fact that these three species are not presently nesting in the state. Periodic aerial surveys conducted at many of these sites since 2004/2005 have failed to document the species (Hamilton and Cuthbert 2016).
Based on the number and seasonality of records detailed in the Minnesota Ornithologists’ Union’s (MOU) seasonal report database, these three herons have a summer status of vagrant (Little Blue Heron), visitant (Snowy Egret), and regular (Cattle Egret). All Minnesota nesting sites for the Cattle Egret are along the western margin of the state, adjacent to the Dakotas, where a larger population has been nesting since the 1970s (Tallman et al. 2002). As a migrant, the Cattle Egret is regularly seen in the same western prairie and eastern deciduous forest provinces where it is observed in summer, but it is a rare migrant in the coniferous northeastern region. Many of the larger flocks in western counties in the fall are juveniles, probably wandering from colonies in the Dakotas (Ellwanger 1997). There are scattered spring records (about 6) in the northeastern counties (Laurentian Mixed Forest Province) and many late fall records (about 20) along the North Shore of Lake Superior in all 3 counties at birding hot spots, where vagrant species are often sited. The dates range from mid-October to mid-November and fit the pattern of this egret dispersing long distances after the breeding season.
During the MNBBA, participants reported 7 Cattle Egret records in 7 different blocks; all were coded as “observed” records (Figure 2 and Table 1). Although surveyors originally reported 2 “possible” records, lacking any documentation to support possible or probable nesting, they were changed to “observed.” As noted earlier, Cattle Egrets can travel far from the breeding colony to their primary foraging territories. As a result, unless birds are seen on the nest, other observations cannot reasonably be assumed to indicate possible or probable breeding status.
During the 5-year atlas period, other Cattle Egret breeding season records were submitted to the MOU. The total of 22 records, MNBBA plus those submitted to the MOU, are all distributed throughout the western and southeastern colonies similar to the distribution described above. Although the Cattle Egret occurs every year during the summer nesting season (June and July), with scattered records in 2 to 10 counties each year, breeding evidence has not been documented since 1992.
*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.