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Eastern Bluebird

Sialia sialis

Order:
Passeriformes
Family:
Turdidae
Sections

Distribution, Migration and Habitat

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Figure 1. Distribution of the Eastern Bluebird.

Small numbers winter north to the Great Lakes.

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eBird range map for Eastern Bluebird

Generated from eBird observations (Year-Round, 1900-2018)

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 Eastern Bluebird.

Breeding Range

Figure 1. Widespread in e. North America. Northern boundaries from s.-central Saskatchewan (primarily eastern parklands, occasionally north to Saskatoon and Greenwater Lake districts; Smith 1996b), s. Manitoba (north to ca. 52°N; http://www.birdatlas.mb.ca/mbdata/maps.jsp?lang=en , and central Ontario (http://www.birdsontario.org/atlas/maps.jsp?lang=en ).

In s. Quebec, occurs in all regions south of ca. 50°N; more widespread along the Canadian Shield and Appalachians; northernmost records are from Abitibi, Gouin Reservoir, North Shore, Rupert Bay lowlands (Gauthier and Aubry 1996b). Also occurs locally in New Brunswick (most abundant in the east), on Prince Edward I., and in central and sw. Nova Scotia (http://www.mba-aom.ca/jsp/map.jsp ).

Breeds south throughout the e. U.S. to s.-central Florida (but absent from the extreme south and Keys; Stevenson and Anderson 1994b), and on the Gulf Coast. Breeds west (locally through the Great Plains states, where range extends west primarily along river valleys) to se. Montana (rare but regular; Montana Bird Distribution Committee 2012), extreme ne. and se. Wyoming (rare and v. local; Faulkner 2010), e. Colorado (see below), central and sw. Nebraska, w. Oklahoma (absent from panhandle; widespread elsewhere; Carter and Duggan 2004), and central Texas (http://txtbba.tamu.edu/species-accounts/eastern-bluebird/).

Western boundary of range is in e. Colorado, west to the base of the foothills (Andrews and Righter 1992). Also breeds in the Huachuca, Chiricahua, and other mountain ranges of extreme se. Arizona (Corman 2005) south through the Sierra Madre Occidental, into the highlands of central and s. Mexico to Oaxaca, in se. Tamaulipas and into the interior of Chiapas Mexico, w.-central Belize (Mountain Pine Ridge -- rare and local, may be extirpated; L. Jones), sw. Guatemala, e. El Salvador, and lowland pine (Pinus) savanna of ne. Honduras and n. Nicaragua. Locally, the species is found in the Sierra de Tamaulipas and low pinelands of e. Honduras and n. Nicaragua (Howell and Webb 1995).

Also resident in Bermuda, >1000 km from any point in continental N. America (D. Wingate; see Demography and Populations: population status.

See also Systematics: subspecies for range based on subspecies.

Winter Range

See Fig. 9. During mild winters, species may remain sporadically north to S. Dakota, Minnesota, s. Ontario, Quebec, and New England states (eBird data). Winters more regularly in westernmost Oklahoma, s. New Mexico, w. Texas, and ne. Mexico, generally at lower altitudes. North American individuals occasionally reach w. Cuba (Garrido and Kirkconnell 2000) and Bermuda during winter.

Distribution Outside the Americas

No records (e.g., Alstrom and Colston1991), perhaps not surprising for a species that undergoes only short-distance migrations.

Nature of Migration

Migration is associated with weather and/or food availability. Known as a “partial migrant” -- some individuals within populations migrate and some take up winter residency near or on breeding sites. Studies needed showing extent and distribution among local individuals of those that do or do not migrate, and of causes of migratory movements vs. residency.

Maximum distance between breeding and wintering areas > 2,100 km, reported for movement between w. Manitoba and central Texas (Bird Banding Laboratory [BBL] data). Anecdotal information suggests that migration versus year-round residency is a matter of degree, with a greater proportion of individuals from harsher winter climates migrating than from milder winter locations. Study of individual variation in migration, opportunistic movement, and residency are clearly needed, perhaps particularly for populations breeding and residing in Mexico and other Central American locations.

Timing and Routes of Migration

Migratory routes not explicitly or systematically studied. Some anecdotal information on seasonal movements of eastern populations suggests that bluebirds move to avoid snow and freezing rain; migration is more strictly north-south in the eastern portion of the range than in other regions (Pinkowski 1971a). In the se. U.S. (Florida, Georgia, N. and S. Carolina), band recoveries include those from individuals banded in previous breeding seasons from New Hampshire to se. Michigan; while recoveries in the Gulf states (Texas, Louisiana, Mississippi, Alabama) include migrants from w. Manitoba to central Ohio (BBL data). Evidence suggests that some northern migrants pass over resident populations to winter farther south (Pinkowski 1971a).

Spring

Onset of spring migration is poorly defined in some portions of the range because of the difficulty of distinguishing residents from migrants. Migration periods for various locations where migrants are distinguishable from residents follow. In Missouri, Eastern Bluebirds arrive in late Feb and the numbers of new birds peak in mid-Mar–early Apr (Robbins and Easterla 1992). In Ohio, arrive during the last half of Feb to early May, with numbers peaking between the 10 Mar–5 Apr (Peterjohn 1989b). In Minnesota, migrants arrive during early Mar to mid-May, with peak numbers in early Apr (Janssen 1987). In Cape May, NJ, numbers are greatest in Mar (Sibley 1997); in Massachusetts, greatest numbers in late Feb or Mar (Veit and Petersen 1993); in s. Quebec, numbers are greatest in mid-Mar–early Apr (Gauthier and Aubry 1996b). In ne. Mexico winter visitors occur through Mar (Howell and Webb 1995).

Fall

Arrival and departure dates for various locations where migrants are distinguishable from residents follow. In Minnesota, departure dates are from early Sep–late Nov or Dec, with peak numbers in late Sep–late Oct (Janssen 1987). In Ohio, departures occur from mid-Sep–early Nov or Dec, with peak departures in Oct (Peterjohn 1989b); in Missouri, arrive mid Sep, peaking mid-Oct–mid-Nov (Robbins and Easterla 1992); in Arkansas, mid-Sep through Nov (James and Neal 1986); in Massachusetts, Oct and Nov (Veit and Petersen 1993); in Cape May, NJ, late Sep through Dec, peaking late Oct–mid-Nov (Sibley 1997); in Florida, arrive late Oct and Nov, increasing local populations by >100% (Stevenson and Anderson 1994b). In ne. Mexico winter visitors occur as early as Nov (Howell and Webb 1995).

Migratory Behavior

A diurnal migrant (Bent 1949, Graber et al. 1971); may travel in flocks of up to several hundred birds, although most migratory groups are much smaller. Juvenile flocks may migrate independently of adults, remaining cohesive throughout winter and heading north as a flock the following spring. Males frequently arrive at northern breeding grounds before females (Pinkowski 1971a), although pairs often arrive at nest sites together (Krieg 1971, Pinkowski 1974a). Occasionally, females occupy nesting cavities before a male recruits to the territory (PAG pers obs).

The tendency to migrate and spring arrival dates are unrelated to age (Pinkowski Pinkowski 1971a, Pinkowski 1977b). Age and sex differences in migration distances remain unknown, but fewer adult birds than those in their first year (compared to juveniles) are among band recoveries at longer distances from breeding/natal areas (BBL data). Migratory behavior may impose constraints on the breeding biology of birds. For example, consistent with the fact that Eastern Bluebird populations in the northern part of their range are migratory and birds in the more southern part of their range are year-round residents or sometimes so-called partial migrants, the clutch sizes of southern populations peak in mid-season, while for northern migrant populations clutch sizes peak early in the season (Dhondt et al. 2002).

Control and Physiology of Migration

Few data; needs study. Migratory restlessness occurs in captive birds in Michigan several weeks before the onset of nesting behavior (Pinkowski 1974a). No other known systematic study of other physiological aspects of migratory movements exist.

Habitat in Breeding Range

Natural, ancestral habitats were likely fire-maintained savannas, open stands of mature pinewoods, over water sites with snags (e.g., beaver ponds), xeric forest openings on summits and exposed shoulders of hills (Kiviat 1982), and eastern boreal forests.

Eastern Bluebirds prefer open habitat with no or little understory and with sparse ground cover, such as lowland pine savanna of Nicaragua (Howell 1965). Modern breeding habitats, documented extensively in e. North America, include orchards, clear-cuts in oak-hickory (Quercus-Carya) forests, burned tracts of jack pine (Pinus banksiana) plains and longleaf pine–slash pine (P. palustris–P. caribaea) woods, upland, and swampy habitats near to major urban areas. In S. Carolina, breeders used >15-yr-old pine stands with open understory and edge habitats more frequently than expected on the basis of the availability of these habitats in S. Carolina. Monitored individuals used older pine stands with closed understory, bottomland hardwoods, and younger pine stands less than expected by chance (Savereno 1991).

As a secondary cavity-nesting species, Eastern Bluebirds are often characterized as nest-site limited. Until recently (Miller 2010), there were no random, replicated, and controlled studies of the effects of nest site limitation on the abundance or breeding success of Eastern Bluebirds. Because secondary cavity nesters “should be more nest-site limited” in younger pine forests of the southeast that have fewer snags than older, structurally more complex forests, investigators predicted that in managed pine forests where the availability of snags is often limited, fewer bluebirds would appear or breed successfully unless nesting boxes were experimentally supplied. While the effect on other cavity nesters was impressive, there was only a weak effect of adding nesting boxes for this population of Eastern Bluebirds, perhaps because their initial density was low. This study nevertheless emphasized the importance of evaluation of “things we say about Eastern Bluebird biology” with random, replicated, and controlled experiments.

Placing nesting boxes in open-canopy areas, including low grass verges of railroad tracts in rural towns, increases the presence of this species. Bluebird use of 2- to 4-yr-old pine plantations was increased when snags and nesting boxes were added (Caine and Marion 1991). Bluebirds used nesting boxes in young loblolly pine (P. taeda) plantations in Mississippi (Hurst 1983). Rare open-cup nests were found in surface-mined lands in Kentucky (Allaire 1976) and on oak limbs in Clemson, SC (Sprunt 1946a) (PAG) and in longleaf pine (Pinus palustris) forests of Alabama. In northern latitudes bluebirds prefer southeasterly facing orientations, while in Athens, GA bluebirds preferred nesting boxes facing northwest (Navara and Anderson 2011). Bluebirds are clearly variable in nest box preference orientation associated with undetermined factors. When settling bluebirds have choices between two-box and one-box sites, they differentially settle in two-box sites (Plissner and Gowaty 1995).

In Colorado, Eastern Bluebirds have bred at approximately 2,440 m above sea level (Andrews and Righter 1992).

In Arizona, where Eastern, Western, and Mountain bluebirds have partly overlapping ranges, Eastern Bluebirds are the rarest of the three species, being local residents in live oaks (Quercus agrifolis) and nearby pines. Western Bluebirds are in an open Transition Zone in the northeast; Easterns use larger trees of the Upper Sonoran Zone woodlands. Mountain Bluebirds are common summer residents in open parts of n. Arizona from piñon-juniper (Pinus-Juniperus) woodland up to the timberline (Phillips et al. 1964a).

Ancestral habitat of Eastern Bluebirds was likely long-leaf pine forests, where secondary cavity nesting bluebirds now interact with other typical species of long leaf pine residents: Red-cockaded Woodpeckers, Brown-headed Nuthatches, Great Crested Flycatchers (Myiarchus crinitus).

Common habitats for Eastern Bluebirds now include golf courses with nesting boxes.The species appears to tolerate and sometimes even thrive in disturbed habitats (Cornell, Kight et al. 2011). Numbers sometimes increase in response to increases in snag densities after controlled burns (Greenberg, Tomcho et al. 2007).

Habitat in Migration

Habitat use during migration is similar to that in the breeding season, but individuals more frequently use the canopies of open forests. Eastern Bluebirds often move along the edges of corridors in spring and fall migration (Levey, Bolker et al. 2005), and this experimental study showed that bluebirds prefer moving along corridor edges (Stokstad 2005).

Habitat in the Winter Range

Open forests, forest edges, pastures, orchards, and parklands. Little is known about the winter range of bluebirds before European settlement. The curious painting by British naturalist Mark Catesby suggests that, in the 1700s, Eastern Bluebirds foraged on the ground in mature deciduous forests in a manner reminiscent of foraging by American Robins (Turdus migratorius) and other ground-foraging thrushes. Eastern Bluebirds move through foraging patches along the edges of corridors, providing a mechanism for seed dispersal (Levey, Bolker et al. 2005, Stokstad 2005).

Historical Changes to the Distribution

Pleistocene and post-Pleistocene distributions of bluebirds were probably limited to fire-maintained mature pine forests, similar to modern-day longleaf pine forests (Finch et al. 2012), and to tree fall gaps in eastern deciduous forests. Eastern Bluebirds expanded into the grasslands of the Great Plains during the early 1900s, probably in response to human-induced increases in trees on former grasslands (Bent 1949). There was some shrinkage in the distribution of Eastern Bluebirds associated with population declines because of colder-than-average winters during the late 1970s, particularly in the northern portion of their range; nevertheless, the rebound of population numbers was dramatic. See Demography and Populations: population status, below.

Populations have expanded in the northwest portion of the range during the past century because of human modifications of habitat, including increases in fenced grazing lands suitable for foraging and provisioning of nesting boxes. Eastern Bluebirds first appeared in Manitoba in the latter decades of the 1800s, in Saskatchewan by the 1920s, and in se. Alberta during the 1970s and 1980s. During the 1960s, the species expanded its range into the Chiricahua Mtns. of Arizona (Ligon 1969a). Breeding range in Florida has also contracted north since 1960 from Dade Co. to Palm Beach Co. (Robertson and Woolfenden 1992a).

See also Conservation and Management: effects of human activity, below.

Fossil History

The first fossil record of Eastern Bluebirds included 3 humeri from an abandoned lime quarry in Marion Co., FL, found among other late-Pleistocene remains (Hamon 1964). Fossils also recovered from Meyer Cave in Monroe Co., IL, from a period of moist and cool climate about 10,000–8,000 years ago (Parmalee 1967a). Sialia sp. noted from the late Pleistocene at Little Box Elder Cave, WY; and from Shelter Cave (12,500–10,000) and Conkling Cave (25,000–12,500) in the n. Chihuahuan desert of New Mexico (Emslie 1985b).

Recommended Citation

Gowaty, Patricia A. and Jonathan H. Plissner. 2015. Eastern Bluebird (Sialia sialis), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA. https://doi.org/10.2173/bna.381