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One species or two? Common Redpoll (left) by Sharon Watson via Birdshare, Hoary Redpoll (right) by Chris Wood.

By Gustave Axelson

The Hoary Redpoll is one of those hard-to-get lifelist-adds that can turn birders into Captain Ahab seeking a little whitish bird. The allure of these little ghost finches has drawn many a lister to places like Minnesota’s Sax-Zim bog—in the dead of winter—just for a chance to lock into a Hoary.

But new research by two scientists at the Cornell Lab of Ornithology presents genetic evidence that reopens questions about the species status of the Hoary Redpoll, long thought to be the frosty cousin of the Common Redpoll. In a paper published this week in the journal Molecular Ecology, Nicholas Mason and Scott Taylor of the Cornell Lab’s Fuller Evolutionary Biology Program show that Hoary Redpolls and Common Redpolls have no differences at all across much of their genomes.

“Based on the samples of DNA we examined for Common and Hoary Redpoll, they’re probably best treated as a single species,” Mason says.

In other words, should this new evidence similarly sway the American Ornithologists’ Union’s checklist committee, all the heroic efforts birders have made to add a Hoary to their life lists may be for naught.

The division of redpolls into different species dates back to before the Civil War. In 1861, legendary ornithologist Elliot Coues (one of the founding fathers of the AOU) described eight separate redpoll species based on their visual appearances. Over time the AOU consolidated Coues’ list, but Hoary Redpoll, which has a snow-white breast, was still considered a separate species from Common Redpoll, which has a brown-streaked breast.

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The researchers compared the DNA of 77 redpolls. The evolutionary tree they reconstructed shows that the three redpolls intermixed extensively in their evolutionary past. If they were separate species the branches of the tree would be much more distinct, as shown for their close relative, the White-winged Crossbill. Adapted with permission from Mason and Taylor 2015, Molecular Ecology; White-winged Crossbill by Nick Saunders via Birdshare.

Mason and Taylor looked beyond the plumage into strands of the birds’ DNA in the most extensive look ever at the redpoll genome. Whereas previous genetic analyses of redpolls looked at just 11 regions of the genome (at most), Mason and Taylor examined 235,000 regions. (That impressive number is a testament to the exponential advances in DNA-sequencing technology, but the researchers are quick to note it’s still less than 1% of the total genome.)

In all, the duo compared DNA from 77 redpolls, including specimens from museums around the world, from the Museum of Vertebrates at Cornell University to the Natural History Museum of Geneva in Switzerland. They found no DNA variation that distinguishes Hoary Redpolls from Common Redpolls. Furthermore, another redpoll species found in Europe—the Lesser Redpoll—also had extremely similar DNA sequences. This extreme similarity among all the redpolls stands in marked contrast to studies of other groups of birds—such as Black-capped and Carolina Chickadees—which show differences at many regions of the genome.

In nature, one of the key differentiators among distinct species is assortative mating, that is, members of a group breeding with each other more often than they breed with members of another group. According to Mason, when it comes to Hoary, Common, and Lesser Redpolls, “There are no clear-cut genetic differences, which is what we would expect to see if assortative mating had been occurring for a long time.”

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The three current species of redpoll—Common, Hoary, and Lesser—stretch around the Arctic in a continuous swath that isn’t necessarily apparent from a normal map projection. Adapted with permission from Mason and Taylor 2015, Molecular Ecology.

Instead, Mason says the world’s three redpoll species seem to be “functioning as members of a single gene pool that wraps around the top of the globe.”

But how could it be that Hoary and Common Redpolls look so different given that their genetic makeup is basically the same? For that answer, Mason and Taylor delved into the birds’ RNA. (A quick flashback to high-school biology: If DNA is like the body’s blueprints, RNA is like the construction foreman communicating the instructions to build physical features, like hair or feathers.)

The physical differences among redpolls are associated with patterns in their RNA, not their DNA. In other words, the variation we see in plumage and size is probably not a matter of genetic variation, but of genetic expression. It’s kind of like how two humans might have the same gene for brown hair, but one person’s might be lighter than the other’s—that gene is being expressed differently. In the same way, Hoary and Common Redpolls have remarkably similar sets of genes, but those genes are expressed differently, causing the plumage and bill-shape differences we see.

To look simultaneously at both DNA and RNA, Mason and Taylor sampled birds—some with highly streaked plumage, some with white plumage, and some with in-between markings— from a large flock that had gathered in a fellow Cornell Lab employee’s backyard in Cortland, New York. If Hoary and Common Redpolls had long been separate species, then the birds sampled should have mostly fit neatly into two categories, both by visual appearance and genetically. Instead, there were a few birds that definitely fit the visual description of what we call a Common Redpoll, a few birds that definitely fit the pattern for a Hoary Redpoll, and a lot of birds in the middle—with varying degrees of whitish breast and faint brown streaks.

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The bird on the left is a classic dark, streaky Common Redpoll, while the bird on the far right is a snowy, small-billed Hoary Redpoll. But many birds lie in between these two extremes. The new research suggests all the Common–Hoary confusion over the years may have been justified. Photos, from left to right, by Sharon Watson, newfoundlander61, Guy Lichter, Stuart Oikawa, and Chris Wood.

“We didn’t find distinct characteristics to separate the redpoll types, but rather a continuum, or a progression, of physical traits,” Mason says. “And many redpolls were somewhere in the middle.”

Next, Mason and Taylor are planning to work their research into an official proposal for the AOU to lump Hoary, Common, and Lesser Redpolls into a single species, based on the genetic evidence. If accepted by the AOU’s Nomenclature Committee, the end result may sting for birders who see a Hoary Redpoll subtracted from their life list. But Taylor hopes his research will change the way people look at redpolls altogether.

“I think this makes them a more interesting bird,” he says. “It means they’re part of an exciting, complicated system that can make a single species look different across different parts of its range.”

For more on redpolls and phylogeny:

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Maps revealed that North American hummingbirds, like the Calliope Hummingbird, migrate along different routes each year, possibly in response to food variability. Photo by LAP75 via Birdshare.

By Jennie Miller

Imagine circling the Earth twice on foot while drinking your weight in flower nectar each day. That’s the human equivalent of what Calliope Hummingbirds do, by wing, twice a year, in their migrations between Washington and Mexico. How such small birds travel such immense distances has puzzled ornithologists for decades because hummingbirds are too tiny to wear GPS tags for tracking. Now finally, through the use of citizen science, researchers have mapped the daily movement of migrating hummingbirds, and outlined a path of hope for the species along the way.

Using data from the eBird citizen-science project, researchers patched together hummingbird sightings from more than 300,000 checklists across North America to track the central hub of migration over a five-year period. Based on the number of eBird sightings at different locations, researchers calculated the average location of hummingbird populations for each day. For example, of the estimated 2 million Calliope Hummingbirds in North America, some individuals were recorded by eBird participants during the study period from 2008 to 2013. Researchers used these sightings to then find the average location of all Calliope Hummingbirds each day and visualize overall movement of the species throughout migration.

“We could not have surveyed the entire United States 365 days a year,” explained Sarah Supp, a postdoctoral fellow at Stony Brook University and lead author of the study. “Citizen-science data gave us that.” The research team also included the Cornell Lab of Ornithology’s research scientist Frank La Sorte and was funded by NASA’s Biodiversity Program. Their study focused on 5 hummingbird species that migrate up to 2,500 miles across North and Central America: the Calliope Hummingbird, Black-chinned hummingbird, Broad-tailed Hummingbird, Ruby-throated Hummingbird, and Rufous Hummingbird.

Published in the January issue of Ecosphere, the maps revealed that the birds hopscotched between different stopover sites each year. For instance, over the five-year study, Calliope Hummingbirds shifted their central path of migration as far as 320 miles east or west between years, switching from routes focused around Tucson, Arizona, to Albuquerque, New Mexico, and from Bakersfield, California, to Las Vegas, Nevada.

According to Supp, this year-to-year variation suggests some “wiggle room” in hummingbird decision-making. The birds could be choosing sites with high-quality food, such as flowers with nectar to fuel their fast-paced metabolism. Such versatility may enable hummingbirds to respond as the rising temperatures of climate change alter the timing and location of flowering plants.

“Under climate change, one of the things we’re concerned about is mismatch in timing for migrating species,” said Supp. “If hummingbirds come north and the plants are already done flowering at the location where they’re expecting food, then that could be a problem.”

North American hummingbirds are especially vulnerable because they are so small, weighing the equivalent of two or three paperclips, and have such high metabolic rates, the fastest of all warm-blooded animals. These limitations prevent them from packing on large quantities of body fat to last them through migration. As a result, they feed continuously as they migrate, requiring frequent access to flowering plants with nectar throughout their route. “For some birds, going for extended periods without food means they get skinny or stressed,” said Catherine Graham, a principal investigator on the study based at Stony Brook, “but for a hummingbird, it could mean death.”

As climate change alters the availability of flowering plants, bird feeders may become an increasingly important source of food for migrating hummingbirds. “Feeders serve as a supplement to natural food for birds,” explained Emma Greig, project leader of the Cornell Lab’s Project FeederWatch. “Especially in extreme climate situations, like a harsh winter, feeders could play an important role in helping hummingbirds survive.”

With 10% of all hummingbird species worldwide threatened by extinction, the study offers optimistic news on the long-term survival of these beloved birds. Says Supp, “It tells us that hummingbirds will be flexible to a certain degree because they are potentially able to sense when it’s time to move, and that time may be different from year to year. It gives us some hope.”

For more on hummingbirds and bird migration:

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H_is_for_Hawk_cover450By Tim Gallagher, editor of Living Bird magazine

Last fall, a remarkable memoir called H is for Hawk, by Helen Macdonald, took the United Kingdom by storm, winning two prestigious awards and rising to the top of the bestseller list. It’s just been released in the U.S. and promises to do the same here. Last fall, our own Living Bird magazine published a review that highlighted Macdonald’s lyrical writing —but as a lifelong falconer I also give her high marks for providing a window into the minds of falconers and their birds.

On the surface, H is for Hawk is a falconry book chronicling the training of a Northern Goshawk, and yet it is so much more. It is a brilliantly written memoir of the darkest time in Helen Macdonald’s life, as she struggled to cope with the sudden death of her father, noted photographer Alisdair Macdonald. The two had been close her entire life. Some of her fondest childhood memories are of hiking through fields together, with binoculars hung around their necks, as she looked at birds and he at airplanes.

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Macdonald was devastated by the sudden loss of her father, Alisdair Macdonald, with whom she had shared a love of nature as a child. Photo courtesy Helen Macdonald.

What makes H is for Hawk special is how Helen Macdonald chose to deal with the grief she felt after her father’s death—by dropping out of human society and spending months alone, training and hunting with a hawk. This is not as strange as it might sound to a non-falconer. She had been working with raptors since childhood and was already an accomplished falconer. She knew that the kind of concentration required to train a hawk would be the best possible distraction for her. What is interesting is her choice of bird: a goshawk—one of the wildest, most difficult to train of raptors.

Macdonald is fascinated by falconry’s ancient roots, and she covers its history and lore excellently in parts of H is for Hawk and an earlier book, Falcon. It’s a fascination I share. As a 12-year-old, the first book I ever read about falconry was a translation of De Arte Venandi cum Avibus (On the Art of Hunting with Birds), by 13th-century Holy Roman Emperor Frederick II. It felt almost like Frederick was speaking to me from across the centuries, guiding me in my earliest falconry endeavors. Many years later, I traveled across Italy, visiting important Frederick II sites—where he was born, where he lived at various times, where he died—and wrote about the experience in my book Falcon Fever. I ended my journey at the cathedral in Palermo, Sicily, leaving a pair of my Peregrine Falcon’s bells at the foot of Frederick’s sarcophagus—alongside the fresh flowers that people still leave there all these centuries later.

I’ve always felt a strong connection with falconers in centuries past. What I learned from Frederick and other authors was how different the training of a raptor is from any other kind of animal training. Hawks are not social animals like dogs or horses—or people. (Only a handful of species—such as the Harris’s Hawk—has any kind of social structure beyond the pair.) Most raptors are loners. There’s no warmth there. They come together as pairs to breed, but for most of the year they lead solitary lives. If they weaken; if they fall ill or become injured, they die. That’s it. There is no pack mentality. No dominance and submission. No hierarchy of power.

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“All of the accipiters can be difficult to train, but the goshawk is the worst, because it’s so big and strong and fierce. There’s even a falconry term called ‘yarak,’ which refers to a state of bug-eyed, murderous intensity goshawks get into sometimes.” Photo of Mabel the goshawk in her first year, courtesy Helen Macdonald.

So punishment doesn’t work with hawks, only positive reinforcement. You feed them. You care for them. You must show them only kindness, no matter what a hawk might do to you. If it bites you, claws you, or grabs your bare hand, sinking its talons deep into your flesh, you must remain impassive, and wait—sometimes for a long time—until the bird deigns to release its hold. You must be a model of patience and gentleness with a hawk.

This is something I find endlessly fascinating about falconry: the fact that even if you’re a mighty king, or an emperor like Frederick II, you must come to your hawk, hat (or crown) in hand, like a supplicant. It’s an unusual relationship, the height of self-denial, perhaps most akin to that of a medieval monk, clad in a hair shirt and sitting alone without comfort of any kind in a cold stone cell.

The early stages of training a hawk (especially one that is wild-trapped or was raised in a free loft) are all about getting the bird accustomed to being close to a human. Sometimes it’s difficult even to get them to sit on your fist, let alone feel comfortable there. And you can’t even look at them, because, in the fang-and-claw world of predators, a fixed stare often precedes an attack. So you must look away, casting your eyes downward through most of the training process.

I remember all too well my early experiences in training a fresh-trapped Cooper’s Hawk—a mid-sized cousin of the goshawk—when I was in my teens. It was a lonely process—for the first two weeks walking back and forth late into the night with the bird on my fist: first in my room, then in my yard, and finally in the field, where I trained her to return to me when I blew a whistle. I’ll never forget the first time she caught wild game, a common House Sparrow, just three weeks after I trapped her. My mind filled with doubt. Would she let me approach her and pick her up from her kill? Or would she fly off with the bird she had caught and resume her life in the wild? She could easily have done that—but she didn’t. Instead she stepped easily up to my fist, finished her meal, cleaned her beak, and shook her feathers—called a “rouse” in falconry parlance, a sure sign of contentment.

At that moment I knew that all the hard work had paid off, and we were a team. I flew her for the rest of the season, during which she caught many more birds and a few rabbits. I released her back to the wild the following spring. This was an ideal situation for the hawk, which got through her difficult first winter—when a majority of young raptors die. And she was released in the mildest time of year.

All falconers are stoics—or at least we try to be. We train ourselves to hide our innermost feelings. We have to, or we’d never get anywhere in the training of a hawk. To these birds, we must always present ourselves as an unshakable rock—an impassive, immovable presence in their lives. Emotions make raptors nervous. They’re the only ones in this relationship who can show their feelings. Unfortunately, I think we falconers sometimes carry this impassivity into our human relationships, holding our feelings in check, hiding our emotional and spiritual anguish from everyone in our lives. In the darkest nights of our soul, we all too often stand alone—with a fierce, unloving raptor on our fist.

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Macdonald isolated herself after her father’s death, conquering her despair by spending months alone training “Mabel.” Photo by Christina McLeish.

This is where Helen Macdonald was mentally and emotionally in the months following her father’s death. Even in the heart of Cambridge, she was cut off from her friends and family, by her own choice. But she did have two soul mates in this endeavor—a wild-eyed goshawk named Mabel and the ghost of author T.H. White, who had trodden this same path in the 1930s. White, famous for writing The Once and Future King, The Sword in the Stone, and other classics, dropped out of human society, moving into a hovel of a cottage in the English countryside to train a goshawk. It was an utter disaster, ending ultimately with the bird’s escape. White’s book, The Goshawk, chronicles his misadventures in great detail. I remember reading it as a teenager and cringing at times at his ineptitude with the hawk. And yet, his writing was so brilliant, I couldn’t help but read it again and again.

White never really stood a chance of succeeding with this hawk. He was a complete novice—had never even handled a bird of prey previously—and yet here he was, trying to train the most difficult raptor of all. This is something that a non-falconer reading The Goshawk or H Is for Hawk might not get. There’s a world of difference between, say, a falcon and an accipiter (such as a Northern Goshawk, Cooper’s Hawk, or Sharp-shinned Hawk). I’ve flown enough falcons and accipiters to know that they are vastly different animals. (It didn’t surprise me when DNA work revealed that falcons are more closely related to parrots than to accipiters.)

All of the accipiters can be difficult to train, but the goshawk is the worst, because it’s so big and strong and fierce. There’s even a falconry term called “yarak,” which refers to a state of bug-eyed, murderous intensity goshawks get into sometimes. They definitely have a reptilian edge to them. If birds are truly dinosaurs, perhaps it’s not difficult to imagine the goshawk’s distant kinship with Tyrannosaurus rex and Velociraptor! White should never have attempted training a goshawk until he’d had some experience flying easier birds. (He did later go on to become an accomplished falconer, successfully flying a goshawk and a number of Peregrine Falcons and other birds.)

Helen Macdonald could certainly have taken the easy way out and spent that season of despair flying a well-tempered Peregrine Falcon or a Merlin, but she didn’t. She had demons to conquer—both hers and T.H. White’s. I won’t spoil it and tell you how things went with Helen and Mabel, but instead encourage you to read the book. H is for Hawk is a courageous tour de force of writing—emotionally honest and harrowing in its intensity. I’m grateful she was willing to share her story.

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Tim Gallagher at age 14. Photo by Janet Gallagher

Tim Gallagher is the editor of Living Birdthe Cornell Lab’s member magazine. He’s pictured here at age 14, with a Red-tailed Hawk and its jackrabbit kill.

For more reviews:

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It takes a big painting to do justice to the phenomenal history and diversity of birds. To create a tribute to the 375-million-year evolutionary history of birds and to the more than 10,000 bird species alive now, the Cornell Lab and Ink Dwell studio combined efforts on a mural project 40 feet high and 3,000 square feet in size. It covers one entire wall of our visitor center.

The mural’s title, “From So Simple a Beginning,” tips its hat to Charles Darwin and a passage he used to sum up his view of evolution, in The Origin of Species:

                             “There is grandeur in this view of life,
with its several powers, having been originally breathed into a few forms or into one;
and that, whilst this planet has gone cycling on according to the fixed law of gravity,

from so simple a beginning,
                                                                 endless forms most beautiful

and most wonderful have been, and are being, evolved.”

Charles Darwin, 1859

One Planet, 243 Families, 375 Million Years

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Concept drawing for From So Simple a Beginning mural, scheduled to be completed in late 2015. Image via Ink Dwell.

“From So Simple a Beginning” provides a visual journey through the many epochs of birds’ evolution from fish to dinosaurs to the present day. The mural features one species from each of the world’s 243 extant bird families painted in bright color and vivid detail. To trace the evolutionary journey, the mural also depicts extinct birds and dinosaurs in monochrome. Everything is painted life size, from dainty songbirds to all 10 feet of a Wandering Albatross in flight, to an extinct Pelagornis with a 19-foot wingspan.

Painting began in 2014 and is scheduled to finish in late 2015, with the artists needing to complete one bird portrait per day on average to meet their goal. Here’s more about the project and its vision, from artist Jane Kim:

 More Than a Mural

In its marriage of art and science, of gorgeous birds painted in exacting detail, the mural invites viewers first to marvel at the diversity of birds and then to contemplate the evolutionary forces that brought them into being, spread them across the globe, and led to their dazzling variety of forms and colors.

To carry the mural’s message beyond those people who come to the Cornell Lab visitor center, we are building an interactive mural feature as part of our All About Bird Biology project. Viewers will be able to explore the mural through high-resolution images, learn the basics about each of the bird families of the world, and explore collections of some of the most impressive and outrageous birds in the world.

Be Part of the Project: Sponsor Your Favorite Bird

In mid-2015 there will be a special opportunity to become part of From So Simple a Beginning: an auction to support individual paintings on the wall. Imagine claiming your favorite bird, family of birds, or even dinosaur with a modest donation. Winning bidders will be acknowledged on the mural website or on the mural wall itself. As donations to the Cornell Lab, bids are valuable contributions to help further our work to interpret and conserve the world’s biodiversity. The auction will happen in Summer 2015—sign up here and we’ll send you an email when the auction begins. Or, if you choose, you can make a gift to the mural project now.

Progress on the mural is well under way—this slideshow depicts some of the stunning details of individual birds. Follow Ink Dwell studio on Facebook and Instagram for regular updates.

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(Images by Danza Chisholm-Sims/Ink Dwell.)

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