Eastern Bluebird

Sialia sialis

The Eastern Bluebird is moving west! Formerly, this bird kept its haunts east of the Mississippi River, but fire suppression and tree plantings have influenced a slow move to the west. Today in the USA, we can find these birds as far west as the eastern slopes of the Rocky Mountains. These birds thrive in open country with few trees, especially if there are enough nest cavities available. Invasive species such as House Sparrows and European Starlings are a threat to the nesting success of bluebirds, as they are more aggressive than native birds who depend on woodpecker holes and other cavities.

Science recognises seven subspecies of Eastern Bluebirds:

• S. s. sialis breeds in eastern North America, east of the Rocky Mountains, from Canada south to Florida. They spend winters south of their breeding range, to Bermuda, northern Mexico, and Cuba.
• S. s. bermudensis lives in Bermuda.
• S. s. nidificans lives in Mexico’s mountains from Tamaulipas to central Veracruz.
• S. s. Fulva lives from south-central and southeastern Arizona, south through western Mexico.
• S. s. guatemalae lives in southern Mexico and northern Central America.
• S. s. meridionalis lives in Central America.
• S. s. caribaea lives on the east coast of Central America.

As of this writing, most of my meetings have been in New Mexico. Except for birds I met in Big Bend National Park, those I met in Texas were in the Guadalupe Mountains near the New Mexico border. The Guadalupe birds I met were part of a mixed flock that were predominantly Western Bluebirds, which made for some interesting side-by-side comparisons.