Bluebirds are a beloved songbird species found across North America. There are three main species of bluebirds in the United States: the Eastern Bluebird, the Western Bluebird, and the Mountain Bluebird. In Tennessee, the most common bluebird is the Eastern Bluebird.
Eastern Bluebird
The Eastern Bluebird (Sialia sialis) is found across eastern North America, including throughout Tennessee. These birds have bright blue upperparts and a rusty reddish-brown throat and breast. Eastern Bluebirds are cavity nesters and readily use nest boxes put up for them along “bluebird trails.”
Some key facts about Eastern Bluebirds in Tennessee:
- Abundant breeding resident across the state.
- Will use nest boxes, natural cavities, and occasionally open-cup nests.
- Lay 4-6 light blue eggs.
- Primarily eat insects and berries.
- Male has bright blue upperparts, rusty red throat, and white belly.
- Female is duller overall with grayish upperparts.
- State bird of New York and Missouri.
Eastern Bluebird populations declined in the 20th century but have rebounded thanks to nest box programs creating more nesting habitats. Tennessee is now considered to have a stable and healthy population of Eastern Bluebirds.
Western Bluebird
The Western Bluebird (Sialia mexicana) is found in western North America. In Tennessee, it is an occasional winter visitor but does not breed in the state.
Some key facts about Western Bluebirds in Tennessee:
- Rare winter visitor to the state.
- Most sightings are in western Tennessee.
- Bright blue upperparts, reddish breast, and gray belly.
- Very similar to Mountain Bluebird.
- Nests in cavities in its normal western range.
While Western Bluebirds are rare in Tennessee, birdwatchers should keep an eye out for them during the winter months when they occasionally migrate eastward and turn up in the state.
Mountain Bluebird
The Mountain Bluebird (Sialia currucoides) is a western species that is also an occasional winter visitor to Tennessee.
Some key facts about Mountain Bluebirds in Tennessee:
- Rare winter visitor.
- Most sightings are in western parts of the state.
- Male has bright blue upperparts, pale blue throat, and gray underparts.
- Female is grayish overall.
- Nests in cavities in the western states and provinces.
As with Western Bluebirds, birders have the best chance of sighting a Mountain Bluebird in Tennessee during the winter months when they wander eastward on occasion.
Hybridization Between Bluebird Species
On very rare occasions, two different species of bluebirds may hybridize in the wild when their ranges overlap. There a few documented cases of hybrid Eastern x Mountain Bluebirds and Eastern x Western Bluebird pairings. However, these hybrid birds make up an extremely small fraction of the overall bluebird population.
Hybrid bluebirds display intermediate plumage characteristics between the two parent species. Identifying a possible bluebird hybrid in the field would take close examination by an expert birder to determine if it has the mixed markings of two species.
Best Places to See Bluebirds in Tennessee
Here are some top locations in Tennessee to spot bluebirds:
- Chickasaw State Park – Open fields and bluebird boxes along trails.
- Radnor Lake State Park – Oak woods habitat favored by bluebirds.
- Seven Islands State Birding Park – Maintained bluebird trails.
- Cedars of Lebanon State Park – Nest boxes around open meadows.
- Meeman-Shelby Forest State Park – Wooded margins of wetlands.
Many state parks, nature preserves, and even backyards across Tennessee put up bluebird boxes to attract and monitor these colorful songbirds. Finding a park or location with an established bluebird trail is a good bet for sighting these birds during the spring and summer breeding season.
Attracting Bluebirds to a Backyard
Here are some tips to attract bluebirds to your backyard in Tennessee:
- Put up a nest box designed specifically for bluebirds. Place 5-10 yards apart facing open grassy areas.
- Make sure the entrance hole is 1.5 inches across to prevent other bird species from using the box.
- Add a predator guard or baffle to deter snakes, raccoons, and cats.
- Clean out old nests from boxes before each breeding season.
- Offer mealworms, live crickets, peanut bits, and frozen berries from feeders. Avoid sunflower seeds.
- Provide a shallow water bath, mister, or drip for drinking and bathing.
- Limit or avoid pesticide use which reduces insects that bluebirds rely on.
With proper nest boxes and a few bluebird-friendly habitat enhancements, you may be able to attract a breeding pair to nest in your yard.
Bluebird Nesting Behavior
Here are some key facts about bluebird nesting habits:
- Build nests in cavities or nest boxes, 5-10 feet off ground.
- Line nest with grasses and pine needles.
- Lay one pale blue egg per day, up to 7 total.
- Incubation is by female only, lasts 12-14 days.
- Chicks hatch helpless but develop quickly.
- Fledge from nest at 16-21 days old.
- May produce 2-3 broods per breeding season.
Monitoring an active bluebird nest box is a great way to observe their breeding behavior firsthand. However, care should be taken not to disturb the nest too frequently.
Threats Facing Bluebirds in Tennessee
Some key threats and challenges that Tennessee’s bluebirds face include:
- Loss of natural nesting cavities in dead trees and snags.
- Competition for nest sites with non-native birds like House Sparrows and European Starlings.
- Predators including raccoons, snakes, and domestic cats.
- Habitat loss reducing suitable feeding grounds and nesting areas.
- Climate change altering migration patterns, vegetation, and insect prey abundance.
- Use of pesticides and herbicides reducing insect food sources.
Careful habitat management and monitoring of bluebird populations will help ensure healthy numbers in the future. Putting up properly designed nest boxes in good locations can also make a real difference.
Conclusion
Bluebirds are beloved backyard birds in Tennessee, with the Eastern Bluebird being the dominant species across the state. While Western and Mountain Bluebirds are rare winter wanderers, Eastern Bluebirds can be attracted to nest boxes and provided with supplementary feedings in many types of open semi-rural habitats. Careful bluebird conservation and management will help maintain thriving populations of these colorful and cherished songbirds into the future.