Migratory movements of the American Robin across North America.
This animation depicts weekly relative abundance estimates, with brighter color representing higher abundance. The data for this animation were generated using Spatio-Temporal-Exploratory Models to predict population relative abundance at specific times and locations by relating observations of American Robins from eBird to local environmental features derived from NASA remote sensing data. eBird (eBird.org) is a citizen science program run by the Cornell Lab of Ornithology.
Distribution in the Americas
eBird data provide detailed looks at the range of this species throughout the year:
eBird Year-round Range and Point Map for American Robin. Breeding range
Figure 1. Throughout most of North America. Breeds north to western and northern Alaska (uncommon breeder on inland coastal plain; common breeder in Brooks Range; abundant breeder on south side of range; http://www.fws.gov/refuge/arctic/birdlist.html), northern Yukon (Old Crow; ), northern Northwest Territories (Coppermine, Angikuni Lake; Sinclair et al. 2003 ), northern Manitoba (Churchill; Godfrey 1986 http://birdatlas.mb.ca/mbdata/maps.jsp), northern Québec (Lake Minto, Feuilles River, but absent from northwestern Québec; , Todd 1963a ), and northern Newfoundland. Tardif and Lanoue 1996
Breeds west to the Alaska Peninsula and south throughout North America to the southern U.S., including Kodiak Island, Alaska, and the Queen Charlotte Islands and Vancouver Island, British Columbia (
), but not on the Channel Islands or Farallon Islands, California ( Campbell et al. 1997b ). Small 1994
In the U.S., breeds south to the White and Panamint Mountains of eastern California and the southern coastal plain in western California (San Diego County), with only scattered breeding in deserts of southeastern California ( ), southern Nevada (but primarily in mountains and in the north; Small 1994 ), northwestern and southeastern Arizona (primarily upland forests of north-central, and southern Arizona; typically absent from lower desert regions; Floyd et al. 2007 ), southern New Mexico ( Wise-Gervais 2005l http://www.pwrc.usgs.gov/bba/index.cfm?fa=explore.ProjectHome&BBA_ID=nm2001), west-central and southeastern Texas ( ), south-central Louisiana, southern Mississippi ( Tweit 2009 ), southern Alabama, and the panhandle and extreme northern peninsula of Florida, with scattered breeding in Florida south to Marion and Hillsborough counties ( Turcotte and Watts 1999 , Hubbard 1978c , Hamel 1992 , Robertson and Woolfenden 1992a ). Absent from the lower coastal plains in Texas and Louisiana ( Small 1994 ; Hamel 1992 http://txtbba.tamu.edu/species-accounts/american-robin/).
In Mexico, breeds in the interior and on adjacent slopes (1,500–3,500 m) from eastern Sonora and western Chihuahua, and from southeastern Coahuila south to eastern Oaxaca, west of the Isthmus of Tehuantepec ( , Phillips 1991 , Howell and Webb 1995 ). Isolated populations also breed in northern Baja California and ( Russell and Monson 1998 T. m. confinis) in the Sierra Victoria of southern Baja California ( ). Also recorded in summer on Herschel Island, Baffin Island, Aleutians (Amchitka), Pribilof Islands (St. Paul), in the desert lowlands of southern Arizona, Zacatecas, Nuevo León, and Coahuila, Mexico ( Howell and Webb 1995 , Phillips 1991 ), and in southern Florida ( American Ornithologists' Union 1998a ). Fisk 1976
Systematics: Subspecies. Overwintering range
Figure 9. Early winter density of the American Robin.
Based on data from the Christams Bird Count, 2003. Numbers show the number of individuals counted per 100 party hours in each region with CBC count circles.
Leaves most of Canada during winter months but regularly overwinters from southern Alaska and portions of southernmost Canada and the north-central U.S. south throughout the continental U.S., large areas of northern Mexico, and the western Caribbean. Occurs only rarely north of the regular overwintering range from south coastal and southeastern Alaska (
), the coast and southern interior of British Columbia, southwestern Alberta, northern Montana, northern South Dakota, central Minnesota, northern Wisconsin, southern Ontario, extreme southern Québec, southern, and eastern Maine, eastern New Brunswick, southern Nova Scotia, and southern (coastal) Newfoundland (eBird and Christmas Bird Count data; Armstrong 1995a Figure 9).
Overwintering range extends south throughout North America to southern Florida, including the Florida Keys (irregular), the Gulf Coast, and southern portions of Texas, New Mexico, Arizona, Nevada, and California (including the Farallon and Channel Islands, in which the species does not breed).
Overwintering range extends south throughout northern Mexico to southern Sonora (but absent from much of central Sonora; ), southern Zacatecas, San Luis Potosí, extreme northern Veracruz, and throughout northern and central Baja California Norte, with scattered records from southeastern Veracruz and the northern Yucatán Peninsula; resident throughout breeding range in other parts of Mexico ( Russell and Monson 1998 , Phillips 1991 ). Howell and Webb 1995
Very rare and irregular during winter in Cuba and the northern Bahamas (
, Raffaele et al. 1998 ), and regular but uncommon in Bermuda ( Garrido and Kirkconnell 2000 ). Additional winter records from Dry Tortugas, Florida ( Amos 1991 ), Belize ( Stevenson and Anderson 1994b ), and Guadeloupe Island ( Jones 2003a ), Jamaica, Hispaniola (vagrant; 1 record; Phillips 1991 ), and Puerto Rico ( Latta et al. 2006 ). Records from Guatemala require confirmation ( Raffaele et al. 1998 ). Howell and Webb 1995
Distribution Outside the Americas
Vagrant to Greenland (10, September–July), Iceland (2), British Isles (30), Belgium (January–February, 1965), Norway (October 1983), Sweden (24 April 1988), East Germany (19th century; April 1968, April 1972), West Germany (4), Czechoslovakia, and Austria (3;
). Lewington et al. 1991b
Massive seasonal migrations occur across large areas of Canada, the U.S., and Mexico as individuals respond to the seasonal availability of soil invertebrates in spring and of fruit in fall. Conspicuous migratory flocks appear in early spring on temperate lawns, the classic harbingers of spring throughout much of the Midwest and eastern U.S. Restless migrant and overwintering flocks are seen in many new areas within the geographic range of the breeding population, where there is either damp soil or fruit resources. Overwintering numbers may vary significantly from year to year in many (especially northern) areas and flock size can range from a dozen to several hundred individuals.
Most robins breeding in the interior of Canada and the northern U.S. overwinter in the southern U.S. and Mexico, and individuals overwintering in more southern locations tend to migrate longer distances (Brown et al. unpubl.). Robins breeding in southern Mexico and Baja California Sur are non-migratory, and many birds in British Columbia, California, and Newfoundland find winter resources in forested slopes and valleys near their breeding sites.
A recent analysis of data from the U.S. Geological Survey Bird Banding Laboratory found no differences between males and females, and recovery data indicate that most robins migrate 500–1200 km (Brown et al. unpubl.). According to the study, there has not been a shift northward in winter distribution or an increase in migration distance in recent years due to climate change. However, over the past two decades more and more robins are adapting a non-migratory strategy and travelling less than 100 km from their breeding grounds, some even seemingly defending territories in winter months (Brown et al. unpubl.).
Timing and Routes of Migration
Figure 2. Annual cycle of molt, breeding, and migration.
Thick lines show peak activity and thin lines show off-peak.
Figure 2 Fall migration is more complex than a simple shift southward. In eastern states, for example, local birds become increasingly gregarious and begin movements in the Boston, Massachusetts area in early August but have not all left the area until late October. Meanwhile, migrants pass through Maine in September ( ) and Massachusetts in November (Brewster 1906 cited in Tyler 1949a ). In Maryland, peak of migration is 10 October to 1 November ( Tyler 1949a ); peak migration in Florida occurs in October ( Stewart and Robbins 1958 ). Migrants arrive in Cuba and Mexico in November (18 November, Sonora; 26 November, San Luis Potosí), but Mexican populations breeding in the mountains have come to lowland areas by 1–15 October ( Stevenson and Anderson 1994b ). Peak fall migration in Arkansas is mid-late October ( Phillips 1991 ). Peak hourly and daily passage rate at Lake Pontchartrain occurs in late November ( James and Neal 1986 ). Yaukey 2010
In the northern interior of British Columbia, fall movements that begin in early to mid-August peak on Vancouver Island in November and early December, producing overwintering populations along the coast and valleys of the southern interior of that province. Meanwhile, individuals breeding on Vancouver Island leave in July and August for mountains of the southwestern U.S., Mexico, and perhaps Guatemala. Migrants from montane and alpine forests in California join lowland residents in October (
). In Alaska timing of fall migration differs significantly for adults and juveniles; median departure date is 6 September for juveniles and 23 September for adults ( Small 1994 ). Benson and Winker 2001 Spring
Figure 2. From the mid-Atlantic states westward to Arkansas and southward through southeastern forests and sometimes cities, large wintering roosts may be established, but then the birds shift their concentrations with cold fronts or after nearby food resources are depleted. Thus, migratorius, which means “wandering” as well as “migratory,” is appropriate through the winter. In late Feb, large numbers migrate northward through Florida and the Gulf states toward breeding sites ( ). Migrants generally follow the northward progress of the 3°C average daily isotherm ( Tyler 1949a ), reaching Arkansas and Massachusetts by March (Brewster 1906 cited in Tyler 1949a , Tyler 1949a ) and Michigan by early April ( James and Neal 1986 ). Brewer et al. 1991
In the far west,
T. m. propinquus that wintered in Mexico and Central America move northward through California in February. Many T. m. caurinus that wintered in coastal rain forests in Washington and British Columbia arrive in Alaska in late April or early May. Banding data from 1992–1998 in Fairbanks, Alaska, indicate median spring migration date of May 17, with a range of May 1–June 16 ( ). Benson and Winker 2001
In the Colorado Rockies, robins arrive significantly earlier, a full 2 weeks, at high-elevation breeding grounds, in response to changes in climate at lower elevations. This often occurs before snowmelt; the interval between initial arrival and snowmelt has increased by more than 2 weeks in recent decades (
). Inouye et al. 2000 Routes
Analysis of specimens in museum collections can reveal the general wintering areas of the named subspecies (
; see Phillips 1991 Systematics: Subspecies). Even so, there is no evidence that individual robins return to individual overwintering territories as many other passerines do. The term “routes” does not really apply to robin migrations and there does not appear to be strong connectivity between overwintering and breeding grounds (Brown et al. unpubl.). Indeed, evidence from banding records shows that robins overwintering in a particular area originate from widely scattered areas to the north. Individuals recovered in Florida in winter are from as far west as North and South Dakota ( ); individuals banded in Maryland have been recovered during winter from North Carolina to Texas ( Stevenson and Anderson 1994b ). Moreover, some robins may be migratory one year and non-migratory the next, depending on local conditions and resources (Brown et al. unpubl.). Stewart and Robbins 1958
Hand-reared fledglings develop a restlessness at dusk by the age of 13 or 14 days, just when wild birds begin to aggregate in roosts (
). Thus, as juveniles they exhibit genetically programmed behavior that predisposes them toward flocking and subsequent migrations. Interspecific roosting aggregations containing many thousands of robins and blackbirds can occur during migration and in winter months ( Eiserer 1979 ). Apparent nomadism during winter is in striking contrast to the habit of returning to previous breeding territories year after year. Migrating in flocks primarily during the day, birds strike television towers less often than do regular nocturnal migrants ( James and Neal 1986 ). In spite of conspicuous migratory flocks, the full dynamics of the vast movements of some populations of robins and the local wanderings of others remain poorly understood. Stevenson and Anderson 1994b
Control and Physiology of Migration
Captive robins kept on a near-normal spring photoperiod of 12:12 to 16:8 hours develop migratory restlessness that lasts through both the daytime and nighttime hours (
). More information is needed on migratory physiology as well as navigation. Kemper and Taylor 1981
Habitat in Breeding Range
Frequents forest, woodland, and gardens, breeding primarily where lawns and other short-grass areas are interspersed with shrubs and trees, such as residential areas, towns, farmyards, and parks.
In the northwestern U.S. and southwestern Canada, robins breed in both residential areas and riparian areas. In British Colombia, for example, robin abundance increases as one approaches streams and rivers (
). Likewise, in Utah robins are commonly found in riparian habitats ( Shirley 2005 ). Throughout much of the west robins are taking advantage of habitat alteration along many rivers and streams. Conversion of riparian forests to pastureland and urban development has led to an increase in robins, which unlike many other birds can take advantage of multiple habitats, including more natural deciduous habitat as well as agricultural and urban lands ( Norvell et al. 2005 ). Tewksbury et al. 2002
Studies also indicate that robins prefer early-successional forest after cutting or fire (
, Martin 1973e , Hutto 1995c ). For example, in northern California robin abundance was higher in silvicultural areas with low structural diversity and on burned plots ( Sallabanks 1995 ). In Douglas fir ( George and Zack 2008 Pseudotsuga menziesii)–western hemlock ( Tsuga heterophylla) forests of southwestern Washington, the species prefers partially logged stands (commercial thins) over clear-cuts and old growth. In managed grand fir ( Abies grandis) forests of northeastern Oregon, prefers early- and late-seral forest over mid-seral structural classes (RS). Similarly, in coastal hemlock forests of British Colombia, prefers vine maple ( Acer circinatum) gaps ( ). In mixed-conifer forests of west-central Idaho, breeds from low-elevation (600 m) dry ponderosa pine ( Saunders et al. 2006 Pinus ponderosa) habitat types to high-elevation (2,300 m) subalpine fir ( Abies lasiocarpa) types, but primarily in younger growth stages than old growth (RS). In the Sierras of California robins also occur in ponderosa pine forests, often nesting in canyon live oak ( Quercus chrysolepsis) ( ). Purcell and Drynan 2008
In the southeastern U.S and Midwest many robins occur near human settlements and show a tendency to prefer edge environments, including those of forests and agricultural lands, such as cornfields (
, Best 2001 , ENV). Robins are also found in spruce-fir forests in the highest parts of the Appalachian Mountains. where openings or grassy areas are nearby ( Vora et al. 2003 ). In West Virginia, robins establish territories at intermediate elevations and prefer shrubby edges near roads and trials or areas near water ( Hamel 1992 ). Dellinger et al. 2007b
In many areas of the country, robins are becoming increasingly associated with suburban and exurban landscapes. In Virginia, considered an indicator species for exurban development, typified by low density development, patchy forests and sprawling parks for recreation (
) In urban areas, such as Denver, Colorado, robins are observed more often in riparian areas with adjacent grassy lawns than in forested areas ( Suarez-Rubio et al. 2011 ). The development of human settlements as far north as the Canadian arctic is allowing robins to extend breeding to previously hostile environments ( Nelson and Nelson 2001 ). Staniforth 2002
Similar to breeding range.
Habitat in the Overwintering Range
In resident populations, wintering habitats are similar to breeding habitats, but most populations migrate to more southerly latitudes and/or lower elevations (see
Distribution and Habitat: Timing and Routes of Migration), where they overwinter in forests. In the western U.S., the species forms loose flocks that forage on fruit-bearing plants in agricultural lowlands ( ). In central Oregon it is the most abundant bird in old-growth juniper and shrub-steppe habitats, often in large flocks of up to 350 ( Sallabanks 1992a ). In the southeastern U.S., the species overwinters mostly in bottomland woods near fruiting trees; generally in moist woods in early winter, but in late winter commonly on lawns, pastures, and other open places ( Reinkensmeyer et al. 2008 ). Commonly found in habitats dominated by invasive fruiting plants, including bush honeysuckle ( Hamel 1992 Lonicera spp.), holly ( Ilex spp.), Chinese tallow ( Sapium sebiferum) and camphor trees ( Cinnamomum camphora) ( , McCusker et al. 2010 , ENV). Zika 2010
Historical Changes to the Distribution
Size of breeding range has increased progressively with establishment of farmlands and homesteads, followed by the increasing area devoted to suburban parkland in the U.S. and Canada.
During the 20th century, breeding range has gradually extended from Piedmont of South Carolina into coastal plain of southeastern states. Apparently, after several years, watered lawns and lawn-like pastures develop the densities of soft invertebrates the robin seeks in the breeding season (
). In 1932, southern limits were northern Mississippi, northern Alabama, northern Georgia, and upper South Carolina. Species now breeds regularly in suburban sites along Gulf Coast and in Tallahassee and Jacksonville in northern Florida. Has bred in Ocala and Tampa in central Florida ( Odum and Burleigh 1946 ). Absence of muddy worm castings used elsewhere for nest-building may limit further southward expansion in Florida, even in parkland areas, perhaps because the soil is too sandy for the common earthworm ( Stevenson and Anderson 1994b Lumbricus terrestris). Great Plains
Robins moved in during the early 1900s, although not immediately (
), as settlers planted trees and introduced earthworms into prairie soils in Kansas and elsewhere in the Great Plains ( Walcott 1974 , Tyler 1949a ) and as neighborhoods developed ( Phillips 1991 ). First record for southern Arkansas (Union County) in 1955 ( Barrows 1912b ). James and Neal 1986 Southwest and California
Range extended southward and westward into Texas (
), Arizona, New Mexico, and California ( Peterson 1960 ) by the 1950s, with nesting in Tucson by 1965 and Phoenix by 1980 ( Phillips 1991 ) as well as Blythe and Yuma ( Monson and Phillips 1981a ). Range also spreading in southern Coahuila ( Rosenberg et al. 1991 ). No breeding records for the San Francisco Bay area, California, before 1915, but then irrigation allowed earthworms to come nearer to surface and made area suitable for breeding robins ( Phillips 1991 ). It took 25 yr for robins to become established in Pasadena, California, after it became a residential city ( Storer 1926 ). Van Rossem 1942e
Numerous late Pleistocene and Holocene records from Virginia, Tennessee, Florida, Texas, Missouri, Nevada, Arizona, New Mexico, California (references in
), and New York ( Lundelius et al. 1983 ). Steadman 1998