Birds display a remarkable spectrum of colors, with red species being particularly striking. Their vibrant plumage often sparks curiosity about their identity and the biological processes behind their brilliant hues. This article explores prominent red bird species in North America and the scientific reasons for their distinctive coloration.
Common Red Birds of North America
The Northern Cardinal is North America’s most recognized red bird. Males display brilliant red plumage, a black mask, and a thick, reddish-orange bill. Females are buff-brown with red hints on their crest, wings, and tail, retaining the crest and bill. These common year-round residents are found across the eastern and central U.S., parts of southeastern Canada, and Mexico, inhabiting woodlands, gardens, and backyards. Their whistled songs are a familiar sound, used by both sexes for territory defense and communication.
The male Scarlet Tanager sports a brilliant red body contrasting with black wings and tail during spring and summer. Females and non-breeding males are typically olive-yellow with darker olive wings and tails. These birds breed in deciduous and mixed forests across eastern North America, often staying high in the canopy, making them hard to spot. Their song is a burry, rambling warble, accompanied by a distinctive “chick-burr” call.
The male Summer Tanager is entirely bright red with a pale, thick bill, distinguishing it from the Scarlet Tanager by its lack of black wings. Females and immature males are bright yellow-green. Summer Tanagers breed across the southern and eastern U.S., favoring open woodlands like oak, hickory, or pine forests, and cottonwood-willow forests in the Southwest. They often forage high in the canopy, catching insects in flight. Their song is a sweet, whistling tune similar to an American Robin’s.
The male House Finch exhibits reddish coloration on its head, breast, and rump, varying in intensity from rosy red to orangish depending on diet. Females are streaky brown with indistinct markings. These adaptable birds are common in urban and suburban areas, farms, and canyons, often frequenting backyard bird feeders. Their cheerful, warbling song is a common sound, along with a sharp “cheep” call.
The Vermilion Flycatcher male is a small, vibrant bird with brilliant orange-red underparts and a crest, contrasted by a dark brown mask through the eyes and a brown back, wings, and tail. Females are more subdued, with light brownish-gray upperparts and whitish streaked breasts, often with a red or yellow wash on the underparts. These flycatchers are found in open habitats of the American Southwest, including arid scrublands, deserts, and riparian woodlands, where they perch low and sally out to catch insects in flight. The male performs an aerial courtship display, puffing up his feathers and fluttering high while singing.
Why Birds Are Red and Other Red Birds Around the World
The striking red coloration in many bird species stems from carotenoid pigments. Birds cannot produce these pigments; they obtain them through their diet by consuming carotenoid-rich foods like fruits, seeds, and invertebrates. Once ingested, yellow carotenoids (e.g., lutein, zeaxanthin) are biochemically transformed, often in the liver, into red ketocarotenoids, which are then deposited into growing feathers. This conversion involves specific enzymes like CYP2J19.
The intensity of a bird’s red plumage reflects its foraging ability and overall health, as acquiring and converting carotenoids requires a robust physiological state. Brighter red plumage serves as a signal to potential mates, indicating a bird’s quality and fitness. This biological mechanism is widespread, seen in species beyond North America.
Many other bird species globally showcase brilliant red plumage. The Scarlet Ibis, found in coastal areas and wetlands of South America and the Caribbean, is almost entirely scarlet, acquiring its intense color from the crustaceans it consumes. Another example is the Red-billed Firefinch, a small finch native to Sub-Saharan Africa, where males display dull scarlet feathers and both sexes have a pink bill. These examples illustrate how diverse species across different continents have independently evolved to utilize dietary carotenoids to produce their vibrant red displays.