Birds in the Cardinal Family

In 2009, the American Ornithological Society moved the Scarlet Tanager out of the tanager family and into the cardinal family, where DNA said it belonged. The field guides had to be updated. The bird did not change at all.

That reshuffle is the most useful way into Cardinalidae, the family colloquially called the cardinals. Cornell’s Birds of the World puts the current count at 53 species across 14 genera, ranging from the Northwest Territories down to Argentina and Uruguay. Almost none of them look like the bird that gave the family its name.

The three true cardinals

The genus Cardinalis contains only three species. The Northern Cardinal (Cardinalis cardinalis) is the one most North American birders know: the male brilliant red with a swept crest and a black face mask, the female tawny buff with a pink bill and the same heavy crest. Audubon’s field guide records the species at 8 to 9 inches long. It is the state bird of seven eastern states and has expanded its range northward over the past century into southeastern Canada.

The Pyrrhuloxia (Cardinalis sinuatus), called the desert cardinal, occupies the arid scrub of Arizona, New Mexico, and Texas that the Northern Cardinal mostly avoids. Its body is brownish-grey with red highlights on the crest and tail, and its bill is rounded and parrot-like - suited to the heavy seeds of mesquite and cactus fruit. Audubon notes its populations are in slight decline as desert habitat in the northern range gives way to development, a different trajectory from the expanding Northern Cardinal.

The third member of the genus, the Vermilion Cardinal (Cardinalis phoeniceus), is confined to scrublands in northern Venezuela and northeastern Colombia.

The grosbeaks and buntings

Grosbeaks are named for their bills - thick, triangular, built for cracking seeds that smaller songbirds cannot manage. The Rose-breasted Grosbeak (Pheucticus ludovicianus) breeds across eastern North America, then migrates nocturnally to Central and South America. Audubon measures the species at 8 inches. The male carries a rosy-red triangle on a white breast framed by a black head. The female looks so different - streaked brown with a heavy bill - that first-time observers regularly reach for a different name. Its western counterpart, the Black-headed Grosbeak (Pheucticus melanocephalus), hybridises with the Rose-breasted at the narrow seam of the Great Plains.

The Passerina buntings push the family’s visual range further. The Painted Bunting (Passerina ciris) male carries blue on the head, green on the back, and red on the breast and rump - a combination that earned it the French name nonpareil, meaning without equal. Audubon lists it as a species of conservation concern, with East Coast populations declining from habitat loss and trapping of adult males for the cage-bird trade on Caribbean wintering grounds.

The Indigo Bunting (Passerina cyanea) poses a different kind of puzzle. The male is not blue. Audubon’s field guide explains that the species contains no blue pigment - the colour is produced entirely by the structural diffraction of light through the feather barbs. The bird is physically black. In flat light the blue disappears. In full sun it is the colour of a clear June sky.

The Indigo Bunting navigates by the stars. Ornithologist Stephen Emlen demonstrated in planetarium experiments in the 1960s that these birds orient themselves by identifying the pattern of stars that appears to rotate the least - specifically Polaris, Ursa Major, and Cassiopeia - and use that fixed reference to guide their nocturnal migration across the Gulf of Mexico.

The tanagers who weren’t tanagers

The Piranga species look like tanagers, were classified as tanagers for most of ornithological history, and turned out by molecular evidence to belong in Cardinalidae. Cornell’s Birds of the World attributes the reclassification to DNA analyses showing Piranga species are more closely related to grosbeaks and buntings than to any true tanager. The Scarlet Tanager (Piranga olivacea), Summer Tanager (Piranga rubra), and Western Tanager (Piranga ludoviciana) are all cardinal family members. Their bills are thinner than a grosbeak’s. The family absorbed them on the basis of ancestry, not looks.

What the name conceals

Cornell’s Birds of the World notes that membership in Cardinalidae is not easily defined by any single physical feature. Cornell’s data shows roughly 82% of species at least concern status overall, though the Painted Bunting’s trapping pressure and the Dickcissel’s situation are real concerns that the aggregate figure obscures - wintering flocks of the Dickcissel (Spiza americana) in the Venezuelan llanos, which can number in the millions, have been sprayed with pesticides since the 1960s to protect grain crops. A species that breeds quietly in Kansas hayfields is simultaneously one of the most heavily persecuted concentrations of birds in the Western Hemisphere.

The Northern Cardinal is, within its own family, an atypical member: resident, non-migratory, conspicuously coloured, and confined to a small genus. The white cardinals occasionally seen at feeders are leucistic individuals of this same species. The birds around it - the buntings with their structural colour, the tanagers rerouted here by DNA, the Dickcissel pressing south toward Venezuela - carry the same family name under considerably stranger circumstances.

The family is not named after its most representative member. It is named after its most famous one. The rest have been carrying the borrowed name ever since.