As one of nature’s rarest colors, only a small percentage of animals are blue. There are just three species of bluebirds in North America, and all three are boldly blue - at least in the case of the males.
North America has more than its fair share of blue birds when you include Blue jays, Indigo buntings, and a handful of other colorful species.
Bluebirds are members of the thrush family Turdidae and belong to the genus Sialia. There are just three species; the Eastern bluebird, the Western bluebird, and the Mountain bluebird.
Each species shares one thing in common: the males are primarily blue, whereas the females are duller but still have some blue plumage.
This is a guide to North America’s three species of bluebirds.
Eastern Bluebird (Sialia sialis)
Female Eastern Bluebird
Eastern Bluebird in flight
Eastern Bluebird eating mealworms from a bird feeder
16cm to 21cm
25cm to 32cm
28g to 32g
As the name suggests, the Eastern bluebird is most common across the eastern half of the USA, southeastern Canada, and south to Mexico, Guatemala, Honduras, Costa Rica, El Salvador, and Costa Rica. They’re both resident and migratory - northernmost populations head south in fall and winter, whereas southern populations stay put.
They’re a common bird and can be seen in open countryside and along roadsides throughout spring and summer. An omnivorous forager, they eat berries, nuts, seeds, and insects and are often seen perched on branches, hedgerows, and power lines before hopping down to scoop up an insect from near the ground.
There are seven subspecies of Eastern bluebirds, including an isolated colony that lives in Bermuda. A highly social bird, they frequently gather in massive flocks and are commonly sighted foraging together, even in the breeding season.
Eastern bluebirds are probably the largest of the three species in length and wingspan, measuring 16 to 21 cm (6.3 to 8.3in) long with a wingspan of 25 to 32cm (9.8 to 12.6in). They weigh 27 to 34 g (0.95 to 1.2oz).
These beautiful birds are strong royal blue across the back and the head, with a rusty brown to warm red-brown breast. They have blue coloration on the wings and tail. Female Eastern Bluebirds are lighter overall with a gray head and back and lighter brown breasts. They retain blue tinges to the wings and tail.
Eastern bluebirds are marginally more slender and elegant than the more rotund Western Mountain bluebirds, but this varies with region and subspecies. They lack Western bluebirds' blue chins and necks, but are otherwise similar in appearance.
The only area where Eastern and Western bluebirds mix in western Texas, where hybridization does occur. Hybridization with Mountain bluebirds may rarely occur further north.
Western Bluebird (Sialia mexicana)
Female Western Bluebird
Western Bluebird perched on a branch
Female (left) and male (right) Western Bluebirds at a feeder
16cm to 19cm
29cm to 34cm
24g to 31g
The Western bluebird has a narrower range than its eastern relative. They’re found in the Pacific Northwest, including California, Oregon, and the southern Rocky Mountains, stretching north just into British Columbia and Montana.
Their southernmost range extends through southern California, Arizona, New Mexico, and Mexico, most commonly the states of Oaxaca and Veracruz. Many birds towards the south of the range are permanent breeders, but others migrate through Central America, rarely as far south as Costa Rica.
An elegant but subtle bird with a quiet, warbling call, the Western bluebird is most likely to be seen in summer, when they forage avidly to feed their young. Like other bluebirds, they nest in cavities. They’re omnivorous but have a more insect-heavy diet than Eastern bluebirds.
Western bluebirds are marginally smaller than their eastern counterparts, measuring 15 to 18cm (5.9 to 7.1in). They weigh slightly less, too, at around 24 to 31g (0.8 to 1.1oz). The Western bluebird is a brilliant royal blue across its top half, including under its neck, which differs from the Eastern bluebird. It has a rusty brown-red neck and breast and a gray breast.
Females are duller than males, especially on the head and back. However, the wings and tail remain tinged with blue.
As mentioned, the only reliable way to tell these apart from Eastern bluebirds is by studying the under-neck (or chin) area. Western bluebirds have a blue patch that Eastern bluebirds lack.
Mountain Bluebird (Sialia currucoides)
Female Mountain Bluebird
Male Mountain Bluebird with insect in beak
Mountain Bluebird perched in a snow covered tree
16cm to 20cm
28cm to 36cm
Mountain bluebirds are also concentrated in the west, but they breed as far north as Alaska, Yukon, Alberta, and British Columbia - much further north than any other bluebird. They’re the hardiest species of bluebird and live high up in the Rocky Mountains.
These hardy bluebirds live throughout much of the USA east of Oklahoma, Kansas, Nebraska, and the western fringe of the Dakotas. The southernmost portion of the range stretches to Mexico, but they don’t head as far south as the other two species of bluebirds which extend south into other parts of Central America.
As the name suggests, Mountain bluebirds live at higher elevations of over 7,000ft and higher. To see them, you need to head up into the hills, but they’re common at high elevations across their range and are easy to spot perched on branches, rocks, telephone lines, etc.
Like other bluebirds, Mountain bluebirds are omnivorous and nest in tree cavities. They’re social but fiercely competitive with other cavity-nesting birds - including other songbirds.
While their range significantly overlaps with the Western bluebird, their preference for higher elevations limits hybridization. Even so, some Mountain bluebirds hybridize with Western bluebirds.
Mountain bluebirds are a very similar size to Western bluebirds, measuring 15.5 to 18 cm (6.1 to 7.1 in) in length and weighing around 24 to 37 g (0.85 to 1.31oz). So, they’re slightly heavier than other bluebirds - probably because they live at higher elevations.
Adult male Mountain bluebirds are the brightest and bluest of any bluebirds, with bright turquoise bodies and wings with a light blue underside. They largely lack the rusty brown parts of other bluebirds. Female Mountain Bluebirds are grayer overall, with a brownish-green underside, breast, and flanks. The wings have a blue tinge.
The Mountain bluebird lacks the rusty brown parts of other bluebirds, thus making it the easiest of the three species to identify. The females are also grayer than other female bluebirds.
Bluebirds are members of the thrush family Turdidae and belong to the genus Sialia. The Turdidae family contains some 174 species, but only around 8 inhabit North America, including the three bluebirds.
It’s important to recognize that bluebirds are not simply blue birds! Strictly speaking, the conjoined spelling of the word bluebird denotes birds belonging to the Sialia genus. There are other blue birds in North America, such as the Blue jay, Blue grosbeak, and Indigo bunting.
There are three species of bluebirds; the Eastern bluebird, Western bluebird, and Mountain bluebird. Like most thrushes, they’re cavity nesters that nest in pre-made cavities, e.g., nesting boxes or old woodpecker nests.
Bluebirds are highly social outside of the breeding season but become increasingly territorial in the breeding season. All three species are partially migratory, with most northern populations migrating south each fall. However, southern populations typically remain in their breeding territories all year round.
Bluebirds are cavity nesters - Mountain Bluebird outside of nesting hole
Bluebirds are common throughout North America and are abundant in most states, though they’re perhaps less common in the central USA.
Bluebirds are found in deciduous, mixed, and pine forests, orchards, fields, parks, swamps, and many other habitats. While present in some rural and suburban areas, they generally prefer wilder areas away from human settlements.
The Easterrn bluebird has the widest range of any of the three species and is also the most common numerically. The population exceeds 20 million, whereas the Western bluebird is more like 10 million and Mountain bluebirds more like 6 million.
The most common Bluebird species in North America, the Eastern Bluebird
Eastern bluebirds have the largest wingspan of the three species, but Mountain bluebirds are just about the heaviest. The margins are slim - all three species are a similar size.
On average, Mountain Bluebirds are the heaviest of the Bluebird species in North America
Western bluebirds are marginally the smallest of the three species on average. They have slightly shorter wingspans than Eastern bluebirds and weigh less than Mountain bluebirds.
On average, the Western Bluebird is the smallest Bluebird species in North America
There are three species of bluebirds in North America: the Eastern bluebird, Western bluebird, and Mountain bluebird.
These are bluebirds - not blue birds! Bluebirds are members of the thrush family Turdidae and belong to the genus Sialia.
No species of bluebird has special protection, and none are considered threatened. However, they are protected by the Migratory Bird Treaty Act of 1918.
Bluebirds in the strictest sense are members of the thrush family Turdidae and belong to the genus Sialia. There are three species: the Eastern bluebird, Western bluebird, and Mountain bluebird. There are many other birds that are blue in color, like the Blue jay, Blue grosbeak and Indigo bunting.
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