Quiz: Can You Pick the Closest Relatives on the Tree of Avian Evolution?

 
ANSWER: Ruby-throated Hummingbird 
Swifts and hummingbirds look and behave very differently. Swifts are insect-eating swoopers that catch flies and airborne bugs on the wing, whereas hummingbirds are nectar-eating flower-sippers that can hover in midair. Yet swifts and hummingbirds are connected in evolution by a common ancestor and classified in the same clade.

The anatomy of swifts and hummingbirds holds clues that they’re related; both birds have tiny feet covered in bare skin, and both have short, thick humerus bones in their wings that facilitate their impressive flying abilities.

Swallows and storm-petrels somewhat resemble swifts and hummingbirds, but that’s a case of convergent evolution. The cigar-shaped bodies shared by swifts and swallows are favored for cutting through the air in search of prey. Storm-petrels independently evolved a favorable wing structure for hovering, though in the case of storm-petrels they hover to snatch zooplankton off the surface of the sea.

Answer: Lesser Spotted Woodpecker
It’s easy to confuse a Downy and a Hairy Woodpecker at a bird feeder; the Downy looks like a black-and-white mini-doppelganger of the Hairy. For many years scientists were confused, too—as Downy and Hairy Woodpecker were classified as close relatives, both considered to be members of the genus Dryobates. But it turns out, that perfect matching plumage is another case of convergent evolution.

The Downy likely evolved feather patterns to make it look like a Hairy so it can confuse predators or competitors for food. By looking like the bigger Hairy Woodpecker, the Downy gains a bit of dominance advantage in the pecking order with other birds.

Recent molecular DNA research has revealed that Downy and Hairy Woodpeckers split apart about 6.5 million years ago. The Downy belongs to a clade that includes Lesser Spotted Woodpecker (which ranges across Europe, Asia, and North Africa), while the Hairy is in a clade with other American woodpeckers like White-headed and Red-cockaded that, somewhat strangely, bear little family resemblance.

Answer: Red-lored Parrot
Twenty years ago, most taxonomists thought that falcons, hawks, and other birds of prey were closely related. But recent DNA analyses support the classification of falcons in a separate clade from hawks and eagles.

In fact, scientists now know falcons are more closely related to parrots than to any other bird of prey. Falcons and parrots share some features of skeletal anatomy that are likely a vestige of a common ancestry before they split around 68 million years ago.

Hawks and Osprey are more closely related to owls, hoopoes, motmots, and hornbills than they are to falcons.

Answer: Northern Cardinal
For years, the Western Tanager and other North American birds with tanager names—like Scarlet and Summer Tanager—were thought to be northern representatives of the diverse true tanager clade, which is centered in Central and South America. Recent DNA analyses have revealed, however, that North American tanagers are in fact members of the cardinal family (Cardinalidae).

The true tanagers are in the Thraupidae family, which includes hundreds of colorful birds such as the Brazilian Tanager and the Seven-colored Tanager. Interestingly, a bird called the Red-crested Cardinal in South America—and several other red-crested, seemingly cardinal relatives of that continent—are also in the tanager family.

Answer: Chestnut-headed Oropendola
When digging into avian phylogeny, it turns out a meadowlark isn’t a lark—it’s a blackbird.

Eastern and Western Meadowlarks are actually more closely related to Red-winged Blackbirds and grackles (in the family Icteridae) than to the Horned Larks that also occupy open-country grasslands in North America.

Icterids are particularly diverse in South America, where another meadowlark relative can be found. The Chestnut-headed Oropendola is a large bird of tropical forests from Mexico to Ecuador that sports an impressive casque, an extension of its ivory-colored bill that reaches up to the forehead.

The Horned Lark is the only regularly occurring bird in the Americas from the Alaudidae family, which includes so-called true larks such as the Eurasian Skylark and the bushlarks of Southeast Asia. The Yellow-throated Longclaw is a meadowlark look-alike that lives in Africa and is classified in the family Motacillidae, which includes wagtails and pipits (including the American Pipit).

Answer: Iiwi
The American Goldfinch—a true finch of the family Fringillidae— is one of the most common birds seen at backyard feeders around North America. People love goldfinches because of the breeding male’s stunning black-and-yellow plumage.

The Saffron Finch, which ranges from Colombia to Argentina, shares many of the goldfinch’s physical features, but it’s not a true finch (surprise, it’s also a member of the South American tanager family). The Verdin is the only North American member of the Remizidae family, which includes the so-called penduline-tits (like Chinese Penduline-Tit and Yellow Penduline-Tit) that are otherwise all found in Eurasia and Africa.

Meanwhile, the spectacular honeycreepers of the Hawaiian Islands—including the blazing red Iiwi—are alongside goldfinches in the Fringillidae family. An ancestor of the Iiwi is thought to have arrived on the islands from Asia about 5 to 7 million years ago, and relatively rapid evolution turned that ancestor into dozens of Hawaiian honeycreeper species.

Answer: Sunbittern
The Kagu is one of the oddest-looking birds in the world—a large flightless species that can perform an impressive spread-wing display to show off boldly patterned wing feathers. A flashy display with flared wings is also a habit of their evolutionary cousin, the Sunbittern.

Kagu are an isolated island endemic species on New Caledonia, an archipelago about 900 miles off the eastern coast of Australia. Sunbitterns, meanwhile, live on the other side of the world, in a range that stretches from northern Central America to Brazil. Both species are also somewhat isolated on the avian evolutionary tree as the only members of their respective families (Rhynochetidae for Kagu, and Eurypygidae for Sunbittern).

Their evolutionary connection goes back to a prehistoric common ancestor that lived on the ancient supercontinent of Gondwana. After the supercontinent broke apart and that ancestor died off (along with most of its relatives), the Kagu was left stranded on remote islands in the South Pacific, and Sunbittern in the forested heart of Central and South America.

The Sungrebe (which isn’t really a grebe) and Capped Heron are also evolutionary oddballs, the sole members of their own genera—Heliornis for the former and Pilherodius for the latter.

Answer: White-fronted Chat
Nectar-feeding birds the world over provide an excellent case study of convergent evolution—hummingbirds, sugarbirds, sunbirds, honeyeaters, and honeycreepers have all evolved remarkably similar-looking long bills adapted for poking into flowers. Yet these five families of birds all come from far-flung regions of the avian phylogeny.

The nearly 200 species of the honeyeater family (Meliphagidae, which includes Tawny-crowned Honeyeater) live in Australia and islands of the surrounding region. Also in Australia lives another bird called the White-fronted Chat—which doesn’t resemble a honeyeater much at all. White-fronted Chats are hardcore insectivores that only occasionally visit flowers. Notably, White-fronted Chats have brush-tipped tongues like honeyeaters and other nectarivorous birds (the better for slurping up nectar).

It turns out the White-fronted Chat is a long-lost honeyeater relative, and the brush-tipped tongue is a vestige of its nectar-sipping evolutionary history.