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. Onset of spring migration is poorly defined in some portions of the range because of the difficulty of distinguishing residents from migrants. Les oiseaux nicheurs du Québec: Atlas des oiseaux nicheurs du Québec meridional. Oklahoma (absent from panhandle; widespread elsewhere; Carter and Duggan 2004), and central Texas ( Arizona (Corman 2005) south through the Sierra Madre Occidental, into the highlands of central and s. Tamaulipas and into the interior of Chiapas Mexico, w.-central Belize (Mountain Pine Ridge -- rare and local, may be extirpated; L. See also Systematics: subspecies for range based on subspecies. 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. Michigan; while recoveries in the Gulf states (Texas, Louisiana, Mississippi, Alabama) include migrants from w. Evidence suggests that some northern migrants pass over resident populations to winter farther south ().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. During the 1960s, the species expanded its range into the Chiricahua Mtns.
Placing nesting boxes in open-canopy areas, including low grass verges of railroad tracts in rural towns, increases the presence of this species.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).You are currently viewing one of the free species accounts available in our complementary tour of BNA. 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 ( 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 (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. Monitored individuals used older pine stands with closed understory, bottomland hardwoods, and younger pine stands less than expected by chance ().In this courtesy review, you can access all the life history articles and the multimedia galleries associated with this species. As a secondary cavity-nesting species, Eastern Bluebirds are often characterized as nest-site limited.