Ask Kenn!

Ask Kenn Kaufman: Will My Feeder Keep Birds From Migrating?

Also this month: What happens when a bird gets lost? And what was the most recent newly discovered bird in the U.S.?

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: Birds have been migrating for millennia. So how do they get lost, and what happens to them when they do?

KK: Avid birders ponder these questions a lot. Finding a bird that’s locally rare, outside its normal range, is among the biggest thrills of birding, so naturally we think about how they got there and what will happen to them.

Such avian strays turn up at any season, but they’re more likely during migration—especially in fall, when inexperienced young birds migrate for the first time. It’s tempting to think a lost bird has merely been blown off course, but that’s usually not true. Only an exceptional storm like a hurricane will blow birds far from where they want to be. These small travelers have amazing instincts for navigation, and if winds carry them off course during a night flight, for example, they can correct for it and get back on track quickly. So in general, when a bird is far out of range—like the Red-flanked Bluetail from Asia seen in Los Angeles this past winter, or the tropical Great Black Hawk that wound up in Maine—it’s likely this individual had faulty instincts and was trying to go the wrong direction.

What happens to a bird that’s far from where it’s supposed to be? Often it’s ill-suited to its new surroundings and it simply won’t survive. That’s what happened to the Great Black Hawk, and this is especially true for long-distance migrants that go the wrong direction. For example, almost all the Blackpoll Warblers nesting in Alaska and western Canada fly eastward in fall before they turn toward South America. Those that show up on the California coast are far off course. Ornithologist Dave DeSante was able to capture a number of Blackpolls in coastal California in fall; by observing their behavior at night, he found that these warblers were orienting toward the southwest, out into the emptiness of the Pacific. There was no possible wintering area they could have reached by flying that direction, so they were doomed by their own instincts.

You’d think that this kind of flawed navigation would be weeded out of the population, because these lost individuals would never reproduce and pass along those genes, but that isn’t the case. And paradoxically, while these “wrong-way” instincts are usually bad for the individual, they can ultimately be good for the species. Sometimes the lost birds wind up in some new territory where they can thrive, and the species may establish a whole new population as a result.

For a spectacular example, consider the Cattle Egrets that reached northeastern South America in the late 1800s, having crossed the Atlantic from Africa. They were certainly lost, and it was sheer luck that they made it to land. But they survived in newly cleared pasture land in South America, and their offspring gradually increased and spread. There are now millions of Cattle Egrets throughout North, Central, and South America, showing that the tendency to wander out of range can sometimes be a winning trait for the species as a whole.

Q: Should I be worried that my bird feeders will stop birds from migrating during the fall?

KK: Concern about how our actions might affect birds and wildlife—that’s always a good thing. But in this case, there’s no reason to worry.

For most species, migratory instincts are more or less hard-wired. That is, birds go at a certain time and travel in specific directions, following patterns that have been established by natural selection over thousands of generations.

In spring, instinct drives birds to get to the breeding grounds at just the right time—early enough to snag a good territory, but not so early that winter conditions still prevail—and to arrive in good physical shape. In fall, there are fewer constraints, so that migration period stretches over half the year, with some species southbound before July and others not moving until December. Very few fall migrants wait to be pushed out by cold weather or lack of food: Instead, most seem to travel much earlier than they would have to. Adult female Short-billed Dowitchers are already flying south from the Arctic by late June, leaving the tundra when food is most abundant. Adult Orchard Orioles begin to depart from northern breeding areas by the first of August, checking out during the peak of summer. If natural food supplies don’t stop them from leaving, artificial food sources won’t either.

This question often comes up in regard to hummingbirds as people consider taking down their sugar-water feeders. The short answer is that feeders won’t cause regular summer resident hummingbirds, or those passing through in normal migration, to change their habits. When I lived in Tucson, I kept feeders up all year, because Anna’s Hummingbirds would stay all winter. Black-chinned Hummingbirds visited the feeders in summer, but they would all depart in October. At the same time, hordes of Rufous Hummingbirds passing through would all continue on southward. Gardens full of flowers and feeders full of sugar-water wouldn’t override their instinct to migrate at the appropriate time.

As to leaving sugar-water feeders up in fall, there’s a wrinkle: A hummer that’s genuinely lost, having flown the wrong direction (see previous question), might discover a feeder and settle in to rely on it. This happens every year with western species appearing in the Midwest and Northeast. In eastern Pennsylvania, for example, the state’s first Anna’s Hummingbird arrived in October 2010 and stayed through the winter, while people in the neighborhood put up more feeders to help it along. In cases like these, feeders haven’t kept the bird from going where it should. These are just individuals with broken internal compasses. Our offerings of sugar-water may help them stay alive longer than they would have otherwise, and we can’t resist rooting for them.

Q: What's the most recent newly discovered bird in the U.S.?

KK: Get ready: This is a long one, but that’s because the answer depends on how we interpret the question.

For new bird species north of the Mexican border, the age of discovery was over before 1900. Charles Bendire discovered the Rufous-winged Sparrow and Bendire’s Thrasher near what is now Tucson around 1872, McKay’s Bunting was discovered in its remote Alaska range in the 1880s, but after that it was rough sledding to find anything else brand new.

Of course, even today, new species are still added to the list because of “splits.” For example, in 2016 the Western Scrub-Jay was split into two species, California Scrub-Jay and Woodhouse’s Scrub-Jay. But these already were recognized as distinct subspecies, so this was just a change in classification, not a new discovery. The same applies to recent splits involving Pacific and Winter Wrens, Eastern and Mexican Whip-poor-wills, and Dusky and Sooty Grouse. 

For this question, I’ll ignore examples like that. So what are the most recent new species that hadn’t been recognized as anything different before they were named?

The Gunnison Sage-Grouse is one candidate. Described to science as a full species in 2000, it hadn’t been recognized even as a subspecies before that. We knew about a widespread western bird called Sage Grouse, but until the 1980s, no one had noticed that those in southwestern Colorado and southeastern Utah were different from those elsewhere. When biologists Jessica Young, Clait Braun, and others started looking closely, they discovered that these birds were smaller, with different tail patterns, longer head plumes, and different courtship displays. Lab work confirmed genetic differences, too. Distinct though they were, these birds had been hiding in plain sight.  

There are parallel stories still developing that involve crossbills—such as the Cassia Crossbill of southern Idaho, just officially recognized as a distinct species in 2017. But although that bird hadn’t been given a subspecies name earlier, it had an unofficial name, “Type 9,” and was even mentioned in some field guides.

So for the purists, I offer two brand-new bird species discovered on islands in the United States within the last 55 years.

In Puerto Rico (which is, of course, part of the U.S.), Cameron and Angela Kepler began doing bird surveys in 1968 in mountain forests of the island. Two of their transects went through a distinctive forest type called elfin woodland, a fog-drenched tangle of short, gnarled trees on peaks and ridges. As they counted the todies, tanagers, and other expected birds, they occasionally saw an odd warbler. It looked something like a Black-and-white Warbler, a regular winter visitor to the area, and something like an Arrowhead Warbler from Jamaica, but not quite right for either.

The Keplers hadn’t expected to find a new and unknown bird; Puerto Rico had been thoroughly studied by biologists already. But it was a new bird, and the Elfin-woods Warbler was described to science in 1972.

Remarkably, the very next year, another new species was discovered in elfin woodland—this time in Hawaii, on the slopes of Haleakala Volcano on Maui.

An expedition called the Hana Rain Forest Project went to study birds in the incredibly challenging rain-soaked forest on upper slopes of Haleakala. Summer 1973 brought unusual drought conditions, and with the relatively dry weather, expedition members went in by helicopter and established a base camp. Two college students on the project, Tonnie Casey and James Jacobi, were thrilled to be able to census rare and little-known members of the Hawaiian honeycreeper group, like Maui Parrotbill and Akohekohe (Crested Honeycreeper). But they were shocked to find an elusive brownish, black-masked honeycreeper that didn’t match any known species.

Further studies established that it was, in fact, a bird new to science. Casey and Jacobi described it in 1974 and named it the Po’o-uli, meaning “black-faced” in the native Hawaiian language.

Sadly, the Po’o-uli was already very rare when discovered and is probably now extinct, with no sightings since 2004. But the Elfin-woods Warbler persists in Puerto Rico, a reminder that amazing discoveries are still sometimes possible.

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Have a bird or birding question for Kenn? Leave it in the comments below, and maybe he'll answer it in a future column.  

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