Partially migratory. Populations breeding in the North American interior and along the
n.Atlantic coast completely migratory. Extent of migration in other populations unknown.
Migratory individuals winter from central and s. U.S. south to at least n. South America.
Many individuals (mostly immatures) remain in wintering areas (particularly in Middle America)
throughout the year. Migratory individuals often appear outside of regular breeding range
(north to s. Canada) during spring, summer, and early fall.
TIMING AND ROUTES OF MIGRATION
Northward migration generally begins in early March At Cape May, New Jersey, returns late
February-mid-March, arriving in breeding colonies by mid-April. Both sexes arrive at same time;
reside approximately 2 weeks in area before breeding activity at colony commences. In
Massachusetts, begins arriving late March (earliest 12 March 1955 at Chatham, MA), with most
arriving early-mid-April. In Ohio, usually arrive 25 April-7 May.
Arrives at breeding colonies in Arkansas third to fourth week March with migration continuing
through mid-May. Arrives in Missouri and Illinois in early April, reaching peak abundance in late
April and May. Arrives in Oklahoma in mid-April (earliest 29 March) and in South Dakota in late
April (earliest 7 April). In San Luis Valley, Colorado, arrive first half April. In Oregon, arrives late
Winter residents recorded in Mexico through April. In Bermuda, migrants recorded 11 March-29
May, peaking end of Mar-late April.
During spring, summer, and early fall, many individuals (particularly birds dispersing after breeding)
typically appear in areas outside of breeding range, although these movements not as pronounced
as in other herons. During this period, individuals have been recorded throughout North America
north to southernmost portions of all Canadian provinces, and in northern Ontario, but numbers
appearing in any given location may vary greatly from year to year, and species may be absent for
long periods. Wandering birds have been recorded 17 April-19 November in extreme sw. British Columbia,
and 10 April-12 October in Minnesota.
In Oregon, most breeding Snowy Egrets depart in September, but have been recorded as late as 25 October,
with migrants seen through early November. In Ohio, breeding population departs by late September, with
migrants recorded through 10-15 October. In other areas where distinctions between movements of breeders
and other migrants have not been made, the species generally recorded through third week September in
Colorado, mid-September in South Dakota (latest date 25 October), mid-September in Wisconsin (latest date 3
November); and most have left Massachusetts by November. In New Jersey, noticeable southbound flights
observed late September-late October, peaking in mid-October. Few observed in Arkansas after September
(latest date second week October). In southern portions of range where species is resident, exact periods of
migration difficult to determine. Migrants and wintering individuals recorded in Mexico by August. Migrants also
recorded on Bermuda 22 August-24 November, peaking through-out October.
Along the Atlantic coast, migrates through Florida, the Caribbean, and northern South America. Majority of eastern
birds winter along the Gulf Coast and on eeastern Caribbean islands. Caribbean recovery sites of hatch-year birds
banded as nestlings in eastern North America included Haiti (14 recoveries as of 1990), Cuba (12), and the
Bahamas (11). An individual color banded in Virginia was seen on 22 January 1970 in Bonaire in the West Indies.
Birds generally remain in Caribbean from October to May. Some Florida birds may have migrated to Panama or remained
as residents. Individuals banded in Louisiana and Mississippi subsequently recovered in Panama. A nestling banded in
New Jersey on 10 August 1968 was recovered in Trinidad on 18 November 1968.
Some western birds withdraw to central California and north Mexico, especially Baja California. Individuals banded in
Colorado have been recovered on both coasts and the interior plateau of Mexico. Oklahoma individuals recovered in
Mexico, Nicaragua, and Costa Rica. Limited migration of western U.S. populations to central California resembles
Black-crowned Night-Heron migration in that region and Black-crowneds often found with Snowy Egrets at colony
sites. Adults from central California largely resident,although hatch-year birds may migrate to Mexico. Nestlings
banded in Nevada and Idaho recovered in west Mexico and Guatemala. Most Central American populations described
as a mixture of resident and migratory birds during winter.
Mexican and Central American birds appear sedentary. Migration of South American breeding populations not well known
but suspected. Southward postbreeding dispersal sketchily reported.
Thanks to Parsons, K. C., and T. L. Master. 2000. Snowy Egret (Egretta thula). In The Birds of North America, No. 489 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.