Identification
Blue Birds
No North American bird has blue pigment in its feathers. The blue is a trick of structure and light, which is why the same bird can look brilliant, dull or black within a few seconds.
The short answer
- Blue in birds is structural color produced by light scattering in the feather, not pigment, so a blue bird backlit or in shade looks gray, brown or black.
- Size splits the group immediately: jays are 11 to 13 in (28 to 33 cm), bluebirds about 7 in (18 cm), and buntings about 5 in (13 cm).
- An eastern bluebird has an orange throat, a western bluebird has a blue throat, and a mountain bluebird has no orange anywhere.
- An indigo bunting is small with a fine silvery bill; a blue grosbeak is larger with a massive bill and two chestnut wingbars.
- Female buntings, bluebirds and grosbeaks are brown or gray, so half the blue birds in your yard are not blue at all.
- Bluebirds and tree swallows ignore seed feeders and come for mealworms, water and nest boxes instead.
A blue bird crosses the yard and lands in the sun, and it is electric. It hops two feet into the shade and turns slate gray. It flies away and for a second, backlit against a bright sky, it looks black. All three of those are the same bird, and understanding why is the single most useful thing you can know about identifying blue birds.
The other useful thing is that there are not many of them, and they sort cleanly by size. Jays are big and loud, bluebirds are thrush-shaped and sit on wires and fence posts, buntings are small and sing from the tops of shrubs, and swallows are in the air. Almost nothing in that list overlaps.
This guide covers the blue birds you are most likely to see in a yard, why they change color, and which of them will ever use a feeder. The method behind it is on the identify hub, and the sibling guides cover red birds, yellow birds, black birds and small brown birds.
Why blue birds change color when they turn#
Red and yellow feathers get their color from pigment: carotenoids the bird eats and deposits in growing feathers. Blue does not work that way. No North American bird produces a blue pigment. Instead, the barbs of a blue feather contain a spongy layer of keratin riddled with air pockets at a scale of a few hundred nanometers, and that structure scatters short blue wavelengths back at you while longer wavelengths pass through and are absorbed by dark melanin underneath.
Two consequences follow, and both matter in the field. First, the effect depends on light striking the feather from in front of you. Light coming from behind the bird passes through instead of scattering, so a backlit blue jay reads as a dark gray silhouette. Second, grinding a blue feather to powder destroys the structure and the blue disappears, while a ground-up cardinal feather stays red. Green birds combine the same structural blue with a yellow carotenoid layer, which is why a molting or worn bird can shift between green and blue.
This also explains something people notice and doubt: two blue birds of the same species in the same yard can look like different shades. Feather wear, angle, cloud cover and the reflectance of whatever is behind the bird all change the result. Photographs make it worse, because a camera meters for the scene and a blue bird against a bright sky comes out almost black. Judge blue birds on pattern, size and shape, and treat the exact shade as the least reliable thing you saw.
Move, or wait, before you decide
If a blue bird looks dull or black, you are probably looking at the wrong side of the light. Take two steps so the sun is behind you, or wait for the bird to turn. Never write off a possible blue bird because the color looked wrong; write off the light instead.
First question: how big is it?#
| Size | Group | Species | Where you see it |
|---|---|---|---|
| 11 to 13 in (28 to 33 cm) | Jays | Blue jay, Steller's jay, California scrub-jay | On the feeder, taking peanuts, announcing itself |
| About 7 in (18 cm) | Bluebirds | Eastern, western and mountain bluebird | On wires, fence posts and nest boxes over open ground |
| 6.7 in (17 cm) | Blue grosbeak | Blue grosbeak | Brushy field edges, singing from a wire |
| 5 to 5.5 in (13 to 14 cm) | Buntings | Indigo bunting, lazuli bunting | Singing from the top of a shrub or a roadside wire |
| 5.5 in (14 cm) | Swallows | Tree swallow, barn swallow | In the air, or on a nest box over open ground |
The jays#
Jays are the blue birds most people actually get on their feeders, and there is essentially no overlap between the three common ones because their ranges barely touch.
| Species | Crest? | Pattern | Range |
|---|---|---|---|
| Blue jay | Yes, blue | Blue above with black barring on wings and tail, white wing patches and tail corners, pale face, black necklace | East and central, spreading west |
| Steller's jay | Yes, tall and sooty black | Blackish head, throat and chest, deep blue body, wings and tail, fine blue streaks on the forehead | Western mountains and the Pacific slope |
| California scrub-jay | No | Blue head, wings and tail, gray-brown patch on the back, white eyebrow, white throat with a partial blue chest band | California and the Pacific Northwest coast |
The blue jay and the Steller's jay both have crests and overlap in a narrow band in the Rockies, where the sooty black front half of the Steller's separates them instantly. The California scrub-jay has no crest at all and a distinctly two-toned look, blue at both ends with a gray back. Inland, its close relative Woodhouse's scrub-jay, split as a separate species in 2016, is duller and grayer with a weaker chest band. Two western birds people expect to be blue are not: the Canada jay is soft gray and the Clark's nutcracker is gray with black and white wings.
Jay behavior is a field mark too. All three carry food away rather than eating it in place, cramming peanuts or acorns into the throat and flying off to cache them, and all three imitate hawks well enough to clear a feeder deliberately. If a blue bird lands, takes three peanuts in one go and leaves, and every other bird vanished a second before it arrived, you have a jay.
The three bluebirds#
Bluebirds are small thrushes, not finches, and they sit upright on an exposed perch and drop onto insects in short grass. The throat is where the identification lives.
| Feature | Eastern bluebird | Western bluebird | Mountain bluebird |
|---|---|---|---|
| Male throat | Rusty orange, continuous with the breast | Blue, cleanly separated from the rusty breast | Sky blue, no orange anywhere |
| Male upperparts | Deep royal blue | Deep blue, often with a chestnut patch on the upper back | Sky blue above, paler blue-white below |
| Belly | White | Gray | White |
| Female | Gray-buff with blue wash in the wings and tail, orange-buff breast | Gray with a duller version of the male's pattern | Gray-brown with blue in the wings and tail, no orange |
| Range | East of the Rockies | Pacific states and the Southwest | Open country of the interior West, often at high elevation |
| Habit | Perch and drop | Perch and drop | Hovers over open ground before dropping, which the other two rarely do |
Say it as a sentence and you will not forget it: eastern has an orange throat, western has a blue throat, mountain has no orange at all. Ranges help too, but they overlap more than people expect in the Southwest and the Great Basin. The eastern bluebird profile has the nest box and mealworm detail, and none of the three will eat sunflower seed.
Bluebirds come for boxes and mealworms, not seed
A nest box with a 1.5 in (3.8 cm) entrance hole on a baffled pole in open ground, plus live or dried mealworms in a shallow dish, is the entire recipe. See nest boxes, mealworms and attracting bluebirds.
The small blue birds: buntings and blue grosbeak#
A male indigo bunting is the purest demonstration of structural color in the yard: uniformly deep blue with a slightly blacker head, a small silvery conical bill, and no pattern anywhere. In poor light he is simply a black bird, and people report him as one every June. He sings from the highest available wire or shrub tip through the hottest part of the day, long after most birds have gone quiet.
| Feature | Indigo bunting | Lazuli bunting | Blue grosbeak |
|---|---|---|---|
| Length | 5 in (13 cm) | 5.5 in (14 cm) | 6.7 in (17 cm) |
| Male pattern | Uniform deep blue, no markings | Turquoise head and back, cinnamon breast band, white belly | Deep blue with two broad chestnut wingbars |
| Bill | Small, silvery, conical | Small, conical | Very large, silver-gray, deep at the base |
| Female | Plain warm brown, faint breast streaking, no wingbars | Warm gray-brown with buff wingbars and a plain face | Rich warm brown with the same two chestnut wingbars as the male |
| Range | East and central | West of the Great Plains | Southern half of the United States, mostly |
| Wingbars | None or very faint | Two crisp white bars | Two broad chestnut bars |
The blue grosbeak is the one people misname most. It is a third longer than an indigo bunting with a bill that looks too big for its head, and the chestnut wingbars are visible at a surprising distance. Where the two buntings meet on the Great Plains they hybridize, producing birds with partial breast bands, and those are best left as unidentified. A male painted bunting has a blue head over a red body and green back, and is unmistakable in a good light and merely dark in a bad one.
Blue birds in the air#
A tree swallow looks iridescent blue-green above and clean white below, with long pointed wings, a shallowly notched tail and an unbroken white throat and chest. It will not land on a feeder, ever, because it eats flying insects, but it takes nest boxes readily in open country near water and often competes with bluebirds for them. A barn swallow is darker blue above with a rusty throat and a deeply forked tail, and a purple martin is dark glossy blue-purple all over and nests in colonies in multi-compartment houses.
If a blue bird in your yard never lands on anything except a wire or a box, you are looking at a swallow, a martin or a bluebird, and no amount of sunflower seed will change that. What works is open short grass, insects, water and a well-sited box on a baffled pole.
A box on a pole needs a guard, and a monitoring habit
Nest boxes for bluebirds, tree swallows and martins are predator magnets without a baffle, and non-native house sparrows will kill adult bluebirds and their young inside a box. Baffle every pole, check boxes weekly through the season, and remove house sparrow nests from boxes you control. Guidance is in nest boxes and baffles.
Which blue birds come to feeders#
| Species | At feeders? | What works |
|---|---|---|
| Blue jay | Yes, dominantly | Whole peanuts, sunflower, a platform or hopper that takes their weight |
| Steller's jay and scrub-jays | Yes | Peanuts in the shell, sunflower, suet |
| Eastern, western and mountain bluebird | Not for seed | Mealworms in a dish, a shallow birdbath, a nest box with a 1.5 in (3.8 cm) hole |
| Indigo bunting | Yes, in small numbers | Nyjer, white millet and sunflower hearts on a low feeder near cover |
| Lazuli bunting | Yes, in the West | Nyjer and white millet |
| Blue grosbeak | Occasionally | Sunflower and millet on a platform near brushy cover |
| Tree swallow, barn swallow, purple martin | No | Nest boxes or martin housing over open ground, insects, no pesticides |
Jays are the group that raises complaints, since they arrive as a family, empty a feeder and shout while they do it. Spreading peanuts on a separate platform away from the main station usually buys the smaller birds their turn, and the full approach is in attracting blue jays and how many feeders and how far apart.
Season and region#
Jays are resident year round and are the blue birds most people see in January. Bluebirds are partly migratory, with northern populations moving south and flocks switching to fruit in winter, so a bluebird at a suet feeder in a February cold snap is not unusual. Buntings and blue grosbeaks are long-distance migrants present only from late spring to early fall, and the males molt into a mottled brown and blue plumage in late summer that confuses everyone. Swallows follow the insects and arrive with the first warm spells.
Work out who is possible where you live with the regional guides or the feeder bird finder, and read the full accounts in the bird profiles.
Frequently asked questions#
Why does my blue bird look black sometimes?
Because blue in birds is structural, not pigment. The color is produced by nanoscale air pockets in the feather scattering blue light back toward you, so it only appears when light hits the bird from your side of it. Backlit against a bright sky, a blue jay or an indigo bunting looks like a dark silhouette. Move so the sun is behind you.
What is the small all-blue bird singing from a wire?
In the eastern and central states, a male indigo bunting. He is about 5 in (13 cm), uniformly deep blue with a slightly darker head, has a small silvery conical bill and no wingbars, and sings through the hottest part of the day. In the West, a bird with a turquoise head and a cinnamon chest band is a lazuli bunting instead.
How do I tell an eastern bluebird from a western bluebird?
Look at the throat. An eastern bluebird's rusty orange runs right up over the throat and chin. A western bluebird's throat is blue, cleanly separated from the rusty breast, and it usually has a chestnut patch on the upper back and a gray rather than white belly. A mountain bluebird has no orange anywhere.
Do bluebirds eat birdseed?
No. Bluebirds are thrushes that eat insects in summer and fruit in winter, and they have no interest in sunflower or millet. What brings them in is live or dried mealworms in a shallow dish, a shallow birdbath, open short grass to hunt over, and a nest box with a 1.5 in (3.8 cm) entrance hole on a baffled pole.
What is the difference between an indigo bunting and a blue grosbeak?
Size and bill. A blue grosbeak is about a third longer at 6.7 in (17 cm), with a very large silver-gray bill and two broad chestnut wingbars that show clearly at distance. An indigo bunting is smaller, has a small fine bill and is uniformly blue with no wingbars. The females follow the same wingbar rule.
Why are half my blue birds brown?
Because the females are. Female indigo buntings, lazuli buntings and blue grosbeaks are plain brown, female bluebirds are gray with only a wash of blue in the wings and tail, and male buntings molt into a patchy brown and blue plumage in late summer. The brown bird beside the blue one is usually its mate.