Ask Kenn!

Ask Kenn Kaufman: Why Do So Many White Birds Have Black Wingtips?

Also this month: Are kingfishers more photo-friendly this time of year? And what bird would Kenn ride if he could?

Who's Kenn? Simply put, Kenn is a national treasure. A renowned birder, author, and conservationist, Kenn Kaufman has spent his life dedicated to observing birds, reading about birds, writing about birds, and sharing the world of birds with others. With all that birdy knowledge in his brain, he also acts as the field editor for Audubon magazine. So, whenever we have a bird question stumping us around the office, we just ask Kenn. And now you can, too! If you have a bird or birding question you'd like Kenn to answer, leave them in the comments below or on Facebook. Maybe next month you'll get the kind of thorough, thoughtful, and even humorous response from Kenn we've grown so fond of over the years. —The Editors 

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Q: After years of trying, I recently got close enough to a Belted Kingfisher to get great photos. A local photographer told me she always found kingfishers easiest to approach in late summer and early fall. Why is that?

KK: As an observer of birders, as well as birds, this is something I notice every year. In August and September, people post on social media that they finally had success in photographing Belted Kingfishers.

Even though this is a common species, it’s a challenge to photograph: always wary, always alert. Try to approach a perched Belted Kingfisher and it will take wing with a loud clattering cry, fleeing before you’re close enough for a photo. Alighting on a distant high limb, it eyes you suspiciously, flaring its bushy crest. Try to approach again and there it goes, across the pond or farther down the river. Even the standard method of using a car as a blind may not work, since kingfishers often flush when a vehicle stops nearby. A frustrated photographer might be tempted to keep chasing the kingfisher until it relents, but of course ethics demand that we shouldn’t harass wildlife.

For a while in late summer and early fall, though, some kingfishers are much less wary, almost seeming to pose for portraits. Why? Because these are young birds, out on their own for the first time and not yet wise to the dangers of the wild.

But at a glance, they don’t look like young birds. Juvenile Belted Kingfishers, full-grown and independent by late summer, look a lot like adults. The most visible difference is in the color of the upper chest band. This band is solid blue-gray on adults, but on juveniles it’s strongly tinged with reddish brown at first, and some of this color can linger until midwinter.

Many of these young kingfishers can be surprisingly tame at first. Apparently their elusive, wary behavior is learned through experience. If they survive their first few months, they become more alert to the approach of predators—and photographers. So if you’re one of the latter, take advantage of this seasonal opportunity and try to get your own kingfisher shots. Once those young birds smarten up, you'll have a much tougher time.   

Q: Why do so many white birds have black wingtips? This has been a longtime curiousity of mine. 

KK: That’s a good observation. On many birds that are mostly white, the longest flight feathers of the wings—the primaries—are black, or have black tips. This pattern shows up especially on water birds: Snow Goose, Whooping Crane, Wood Stork, Northern Gannet, and American White Pelican are all examples. The feathers of the adult White Ibis are entirely white, except for the four outermost primaries, which have big black tips. There are fewer white songbirds, but Snow Bunting and McKay’s Bunting are both mostly white and have black wingtips.

The phenomenon isn’t just black and white, though (pun fully intended). If we include shades of gray, we’ll see even more examples. Most adult gulls are gray and white, but on the majority, the pale gray wings have black tips. Many pale gray terns have darker outer primaries. Some albatrosses, fulmars, and other seabirds are quite pale, but their wingtips are dark.

When the same trait develops repeatedly in unrelated species, we can be sure it conveys some advantage to the bird. In this case, there’s one very promising explanation: The melanin, the pigment that darkens the feather, makes the surface stronger and more resistant to abrasion.

You can see a clear demonstration of this if you find shed gull feathers at the beach (or in a parking lot). Many adult gulls have outer primary feathers that are mostly gray, save for a pattern of black and white near the tip. When one of those feathers is in worn condition, the black parts of the pattern will be intact, while the white areas are worn away completely. The parts of the feather with no pigment simply don’t hold up as well. 

This makes sense because primary feathers are the longest feathers, extending out farthest from the body and playing a serious role in precise, controlled flight. (They’re called “primaries” partly because of their primary importance.) On most birds, they’re also exposed to the elements when the bird is not flying, sticking out past the rest of the folded wing. So they need to be strong, resistant to wear and tear. The melanin in the feathers helps to provide that strength.

Which leads to a different question: Why don’t all birds have dark wingtips, then? Why are the wings of swans and egrets, for example, white all the way to the tips? That's tough to say for sure, but it could be related to the fact that they live in such open habitats, and their primaries are mostly covered by other feathers when they’re at rest. So there isn’t much chance for abrasion against the surroundings. Ptarmigans have totally white wings also, but those chunky cold-weather grouse fly infrequently and poorly on their short, blunt wings. In their case, the snazziest dark tips wouldn’t help. 

Q: If you could ride on the back of any bird, what would it be?

KK: Wow, really? Okay, well, why not?

First off, riding just about any bird humanely would require some technology for shrinking myself. Assuming I could shrink to any size, and any bird was a fair choice, from condors to hummingbirds, which would I ride?

The whole point would be to ride a bird in the air—why bother to ride a turkey walking around on the ground, right? Many birds are impressive fliers, but none are as purely aerial as the swifts. They spend almost all waking hours on the wing, and some are even known to sleep while flying. Recent research proved that the Common Swift from Europe can stay airborne for up to 10 months at a time. (If you choose to ride that bird, you’d better pack a lunch.)

Of the roughly 100 swift species worldwide, one compelling choice would be White-throated Needletail, a big swift from eastern Asia. For years it was rumored to be the fastest bird in level flight, reaching more than 100 miles per hour. (Peregrine Falcons are considerably faster when diving on prey, but velocity in level flight is different.) The speed of the White-throated Needletail hasn’t been totally proven, but I’ve watched this species in China, rocketing through the air with astonishing power. It’s impressive, but it wouldn’t be my first choice.

No, I’d give top honors to the Great Swallow-tailed Swift, an uncommon bird of Mexico and Central America. It might not be the swiftest swift, but to me it’s the most beautiful—a striking creature with long, curved wings and a long, deeply forked tail, usually swept back in a single point in flight. While many swifts are gray, the Great Swallow-tailed is sharply patterned in black and white.

It lives in beautiful places, too. I used to watch for these birds every year while leading trips to Sumidero Canyon, Chiapas, deep in southern Mexico. From overlooks on the canyon’s rim, as evening light glowed on the rock cliffs, we’d watch for that distinctive scimitar shape to come slicing through the sky. Finally we’d see them—often a pair, flying together—zooming toward us, shooting straight up toward the clouds, wheeling and diving a thousand feet down along the cliff face at breakneck speed, swooping across the canyon and coming back our way, all with an effortless grace and hardly a beat of their long wings. It was elegance and poetry expressed as pure motion, and for weeks afterward I would dream about the flight of the Great Swallow-tailed Swift.

So, yeah, if I could ride along and see that view of the world, even for a few moments, that would be my choice.

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