Head to head
Blue Jay vs Northern Cardinal
The blue jay and the northern cardinal are the two showpiece birds of the eastern North American backyard, roughly the same size, both crested, both bold at a feeder, and endlessly paired in imagination as the blue bird and the red bird. They are not close relatives, and almost everything about how they make their colour, sound, and living is different.
| Blue Jay | Northern Cardinal | |
|---|---|---|
| Family | Corvidae, the crow family | Cardinalidae, its own family |
| How the colour is made | Structural: light scattering, no blue pigment | Pigment: carotenoids from the diet |
| Male vs female | Both sexes blue and alike | Male scarlet, female buff-brown |
| Bill | Straight, all-purpose, blackish | Thick, conical, red; built to crack seeds |
| Voice | Harsh screams, rattles, and hawk mimicry | Clear, sweet, whistled song; both sexes sing |
| Diet | Mostly acorns, nuts, and seeds; caches food | Seeds, grain, fruit, and insects |
| Migration | Partial and irregular; many stay year-round | Non-migratory |
| At the feeder | Dominant, noisy, drives off smaller birds | Assertive but quieter; may attack its reflection |
Blue Jay vs Cardinal: common questions
Are blue jays and cardinals related?
Only distantly. Both are perching birds, but the blue jay is a corvid, in the same family as crows, ravens, and magpies, while the northern cardinal is the type species of a separate family, the Cardinalidae, which also includes the grosbeaks and buntings and, oddly, the tanager-like piranga. Their last common ancestor is far back in the songbird tree. Their superficial similarities, the crest, the size, the boldness at feeders, are coincidences of two medium songbirds filling similar roles in the same woods rather than signs of kinship.
Why is the blue jay not really blue but the cardinal is really red?
They use different methods. The cardinal's red is chemical: pigments called carotenoids, obtained from the berries and seeds it eats, are deposited in the growing feather, so the colour is literally in the material and a bird on a poor diet grows in a washed-out orange-red. The blue jay's blue is physical: the feather barbs contain a spongy layer of keratin with air pockets that scatter light and send blue wavelengths back to your eye, while brown melanin behind absorbs the rest. Because the blue depends on the intact structure, grinding a blue jay feather to powder destroys it and the powder is grey. There is, in fact, no known bird that makes a blue pigment.
Which is more aggressive, a blue jay or a cardinal?
The blue jay, by most measures. It is larger-brained, louder, and socially pushy, dominating feeders, driving off other birds, mobbing hawks and owls as a group, and occasionally raiding nests. Cardinals are territorial and a male will fight hard for his patch, including the well-known habit of repeatedly attacking his own reflection in a window or car mirror during the breeding season, but they are not bullies at a feeder in the way jays are. If both come to the same feeder, the jay usually sets the terms and the cardinals wait their turn.