The Distribution Range of the Eastern Bluebird

Many people in the east half of North America are familiar with the eastern bluebird. Folks wonder where bluebirds go because they see them come and go so often. In this article, you will find out what range the eastern bluebird occupies across North America.

Where do eastern bluebirds live? The Eastern Bluebird is a widespread bird in eastern North America. Its range encompasses a little over the east half of the U.S. and Canada. Its range extends to most Central Mexico, south to Guatemala, El Salvador, Honduras, and Nicaragua.

Eastern bluebirds are primarily resident birds throughout most of their range. Throughout the year, birds stay close to their breeding grounds.

Eastern bluebirds’ summer and winter ranges expand and contract only in the northern parts, where migratory bluebirds arrive breed, and later migrate south during the cold winter months.

Eastern bluebird range boundaries

North: As indicated above, the range’s northern boundary expands during the warm months of the year and contracts during the cold winter months.

During the warm months of July through August northern edge of the eastern bluebird’s range includes the southeast corner of the Canadian provinces of Saskatchewan, southern Manitoba, and Southern Ontario (See range map).

During the cold months of December through March, the range’s northern boundary moves south to include Middle South Dakota, M Minnesota, N Wisconsin, Michigan, S. Ontario, S. Quebec, up State New York, N. Vermont, and Maine.

West: The Western boundary of the Eastern Bluebirds’ range includes a small region of eastern Montana, the eastern half of Wyoming, Colorado, and New Mexico.

The Eastern Bluebird is also a resident on Bermuda Island, located some 621 miles east of Florida.

bluebird range-map

Range Map showing the occurrence of the Eastern Bluebird through an annual cycle.

  • Purple Area: Is the region where the Eastern Bluebird is a year-round resident.
  • Orange Area: The region in “orange” is occupied by migratory eastern bluebirds during the period of approximately May 17 and August 31, which corresponds to breeding season.
  • Teal Area: The region in Teal color is occupied only during the non-breeding season, by birds that breed in northern U.S. and Canada and spend the winter in the south.
    Source: eBird-Eastern Bluebird.

How many types of Eastern Bluebird are there?

There are 7 different types or subspecies of eastern bluebirds. Each subspecies occupies separate regions throughout the species range, particularly during the breeding season. 

There is little variation in coloration and measurements among the 7 different bluebird subspecies. In the field, It can be difficult to tell them apart based only on appearance. 

In North America, only populations of bluebird breeding in the temperate regions migrate annually.

Based on color variation and measurements of museum specimens, ornithologists have identified seven subspecies of eastern bluebirds,  including:

  • Sialia sialis sialis: These birds breed in eastern North America, from southern Canada to northeastern Mexico (southern Tamaulipas). They winter from the eastern United States to northern Mexico, rarely to Cuba.
  • Sialia sialis bermudensis: This subspecies is found on the Island of Bermuda.
  • Sialia sialis fulva: This subspecies occurs in southwest U. S. (SE Arizona) South through montane Central Mexico.
  • Sialia sialis nidificans: Found in the Caribbean slope of East-Central Mexico.
  • Sialia sialis guatemalae: Found in Souteast Mexico (Chiapas) and Guatemala.
  • Sialia sialis meridionalis: Occurs in El Salvador, Honduras and Northern Nicaragua.
  • Sialia sialis caribaea: This subspecies is found in East Honduras and Northeast Nicaragua.
A male Guatemalan eastern bluebird (Sialia sialis guatemalae). Photo: Raul Vega.

Climate change and the range of the eastern bluebird

Climate change has both direct and indirect effects on birds, according to research. 

The distribution of eastern bluebirds is closely related to winter and summer temperatures, and climate change may force birds to use more energy for thermoregulation. 

Bluebirds’ ability to maintain basic functions, such as reproduction and migration, can be disrupted due to a higher energy need. A reduction in survival or fitness can also occur. 

The eastern bluebird may shift its range over time due to these increased energy costs to areas with more favorable thermal conditions. Still, the habitat and resources they need to survive could be lacking in the new area they colonize in response to climate change.

The expected shift to the north

In general, global temperatures decrease with increased latitude and elevation. Therefore climate scientists predict a shift in eastern bluebird distribution towards the poles and upwards in elevation. 

Long-term changes in North American bird distributions are already showing clear evidence of latitudinal shifts, with many species shifting their geographic distributions northwards over the past few decades. 

References:

Andrews, P., and R. Righter (1992). Colorado Birds. Denver Museum of Natural History, Denver, CO, USA.

Howell, S. N. G., and S. Webb (1995). A Guide to the Birds of Mexico and Northern Central America. Oxford University Press, New York, NY, USA.

Sullivan, B.L., C.L. Wood, M.J. Iliff, R.E. Bonney, D. Fink, and S. Kelling. 2009. eBird: a citizen-based bird observation network in the biological sciences. Biological Conservation 142: 2282-2292.

Stevenson, H. M., and B. H. Anderson (1994). The Birdlife of Florida. University Press of Florida, Gainesville, FL, USA.

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