Do Eastern Bluebirds Migrate for the Winter?

do eastern bluebirds migrate for the winter

In North America, there are several populations of Eastern Bluebirds (Sialia sialis) that separate and overlap through an annual cycle. These populations vary in their movements and migration patterns with some being permanent residents, other long-distant migrants, and others in between.

In a nutshell.

Do Eastern Bluebirds migrate for the winter?  Some bluebirds migrate, while others do not.  Some populations in the south migrate north to breed during the spring and summer months returning to the warmer southern states during the winter. Other bluebirds are permanent residents in most of the species’ range staying on or near their breeding territories throughout the year. Bluebirds that are permanent residents of northern states may temporarily move south due to inclement weather. As the weather improves, they return to their territories.

Migration of the Eastern Bluebird

Eastern Bluebirds are year-round residents in most of their range in the U.S. (see map below). There are, however, populations that migrate from the south to the north and back every year. Both resident and migratory bluebirds mix in most of their range, and their plumages cannot be distinguished in the field.

The eastern bluebird’s range extends to some northern states and Canada during the spring migration. Winter is the time when birds retreat to the central and southern states, reducing the species’ range.

Bluebirds that breed in the northernmost regions of the species’ range are obligate migrants. These birds must leave the freezing winter temperatures in the region.

Eastern bluebird migration patterns

Banding studies have shown the migratory pattern of the Eastern Bluebird.

Birds banded in the region that stretches from western Manitoba into central Ohio spend the winter in Texas,  Louisiana, Mississippi, Alabama, and Mexico.

Birds banded in the region encompassing New Hampshire to southeast Michigan fly south to spend the winter in the southeastern states of Florida, Georgia, North, and South Carolina.

As noted before, migratory bluebirds returning south join resident bluebirds that remained in their territories year-round.

Situational migrants

Situational Migrants are typically resident bluebirds that stay in or in the vicinity of their breeding territories year-round. Snowstorms and blizzards make food scarce and difficult to find, forcing these birds to fly to areas where food is readily available, which is generally southward.

Situational migrations are temporary. Once the weather conditions improve, birds return, sometimes within days, to their year-round territories. Birds in northern states are more likely to be forced to make temporary migrations than birds in states where severe weather conditions are less likely to occur.

This animation shows the movements and abundance of the Eastern Bluebird throughout an annual cycle. Source: eBird-Eastern Bluebird.

Play de animation multiple times and note how the bluebird range expands and contracts through an annual cycle maintaining a core area where bluebirds are year-round residents.

What Distances do Bluebirds Cover During Migration?

Migration distances have a good deal of variation. Long-distance migrants from Canada cover over 1,400 miles to the southern states and Mexico.

The distance covered by situational migrants varies with the intensity of the weather event.

Severe and long-lasting weather events push bluebirds further south than mild and short-lasting weather events. Situational migrants likely move only a few hundred miles.

bluebirds roosting
Little is know about the roosting habits of the Eastern Bluebird during migration. It is likely that they do not necessarily use cavities but roost in tree branches. Photo: Tom Murray/Flickr/CC by 2.0


Where do Bluebirds spend the night (roost) during migration?

It is not well known where Eastern Bluebirds spend the night or roost during migration. According to field observations, eastern bluebirds congregate in flocks in the winter and seek cover in heavy thickets or other areas in which adequate food and cover resources are available.

Because they are not familiar with the locations of cavities along their migratory routes, they likely roost in trees outside cavities.

Bluebirds that stay in the same territory year-round roost in natural cavities, cavities made by woodpeckers, or nesting boxes offered by humans. These birds are familiar with the locations of these cavities.

Field observations indicate that bluebirds often roost communally. Several individuals may use a single cavity for the night.

Little is known about where bluebirds roost when they arrive in the wintering grounds where there are already resident Bluebirds, and most cavities have been taken.

Perhaps, bluebirds roost in trees while they establish or re-acquaint with their wintering territories. Some may roost in trees until they find a cavity. Others may join other bluebirds for the night in existing cavities.

Migratory bluebirds interact and compete for cavities with other bluebirds and other birds such as titmice, tree swallows, European starlings, and House Sparrows among the most common birds that also use roosting and nesting cavities.

Conclusions:

During the breeding season, a few populations of bluebirds migrate from the southern and middle states to northern states and Canada; returning to the south in the winter. Other bluebirds, however, reside on or near their territories throughout the year.

Little is known about the roosting habits of the Eastern Bluebird during migration.

References:

  • Gill, Frank (1995). Ornithology. New York: W.H. Freeman.
  • Gowaty PA, Plissner GH. (1998). Eastern Bluebird (Sialia sialis), no. 381. In: A. Poole (ed.). The Birds of North America Online. Cornell Lab of Ornithology, Ithaca, New York.
  • Eastern Bluebird, Life History. All About Birds. The Cornell Lab of Ornithology.

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