Rufous Hummingbirds Turning Up in Unusual Places
Is climate change the reason, or are birders just paying closer attention?
Hail, lightning, and gale-force winds had pounded southern Louisiana just hours before in some of the worst weather here since Hurricane Katrina. Untold thousands of birds caught migrating from Central America and Mexico had surely perished in the stormy Gulf of Mexico. But on this spring morning, the Owens yard, just north of New Orleans, is a peaceful and busy haven for the lucky survivors. As a half-dozen humans cradle their coffee cups, a parade of ruby-throated hummingbirds sip sugar water from three feeders set inside cages. Their throats sparkle like Dorothy's slippers in the clean air. The only sound is the crack of a cage door clanging shut on each unsuspecting captive.
Nancy L. Newfield clutches a modified electronic car key, which triggers the doors by remote control, as she keeps a sharp eye out from her vantage point on a damp picnic bench. She is clearly more Glinda than Wicked Witch of the West, wearing both a white sweatshirt covered in hummingbirds and a satisfied expression. A helper retrieves the hummers she traps; Newfield efficiently bands, measures, and weighs each bird, then promptly sets it free to continue its migration. "Hummingbirds are not particularly delicate--they are easy to handle," she says casually, pulling an impossibly minuscule band off a diaper pin to prepare for the next bird.
The next hummer, however, evades her experienced grasp, darting in and out of the cage before the door can close. It is a rufous hummingbird, a feisty species long considered unique to areas west of the Great Plains. People long scoffed at the idea that rufouses are showing up more frequently in this warm and wet region. But thanks to decades of work by Newfield and her many proteges, it now seems likely that the species is dramatically expanding its winter range.
That could make the rufous a kind of canary in the coalmine in the controversy over how humans affect the environment. There's no doubt the Gulf Coast region has changed dramatically in recent years to become far more hummer-friendly. The climate since the 1970s has been generally warmer than in previous decades; hard freezes are fewer and shorter. "I hardly wear winter gear anymore," says Newfield. At the same time, the sudden and dramatic growth of Southern suburbs--and interest in hummingbirds--has led to a proliferation of feeders and yards filled with plants and flowers, some of which bloom through the milder winters. "We've set the table for them," says Van Remsen, an ornithologist at Louisiana State University in Baton Rouge. That means the hummingbirds that stay through the season have a better chance for survival--and to return.
Last winter, for example, Newfield banded 26 buff-bellied hummingbirds, six of which were returnees. And these birds were long thought to only rarely stray very far north of the Rio Grande. The implications extend far beyond the small circle of hummingbird experts and the devoted ranks of hummer lovers, who prize this tiny creature for its magical combination of beauty, toughness, and intelligence. The rufous in the Owens yard may be a sign that migrating birds are more flexible than scientists have realized, and that hardier species may be able to adapt successfully to changing climate and habitat.
Newfield is not a trained scientist, but she has spent more than three decades observing hummingbirds, collecting data, and inspiring and training a whole generation to follow suit. That makes her a revered figure in the field, among academics and amateurs alike. "She's the queen of winter hummingbirds," says Remsen.
The wife of a Navy man, Newfield left her native Louisiana for a series of posts in other bird-rich areas, from Key West to coastal Virginia. She was already hooked on birds. "I saw a hummingbird when I was nine or 10, and I was fascinated," she says, without taking her eyes off the cages. "I didn't know how to identify different ones--and I wanted to know what kind of creature this is." That curiosity led Newfield to be a central player in what she calls "one of the most exciting discoveries in the state's ornithological history."
At first the idea that significant numbers of western hummingbird species could bypass Mexico to spend winter along the distant Gulf Coast was dismissed as nonsense. Such sightings were rejected as false identifications or as occasional anomalies--a bird blown off course or with faulty instincts. "The old-school view was that there might be a few passing through, but that except for a few, they didn't stay," says Remsen, who recalls that the Audubon Christmas Bird Counts in the area prior to the 1970s might log two or three individual western species.
At the time Newfield was a college dropout with two young kids and a husband who was frequently away on business. But as she learned about hummingbirds, she was surprised to find that even the experts had a hard time distinguishing among the many varieties. "Field guides told us it was impossible to separate female ruby-throated from female black-chinned in the field," she notes. Such confusion called into question the accuracy of the counts. And those experts also admonished people not to leave feeders out beyond the fall, lest they lure birds to their death by tempting them to postpone migration. Newfield began to have her doubts that feeders would confuse her visitors. "None of us wanted to be responsible for killing hummingbirds," she says. But her suspicions grew that there was a vast gulf of ignorance concerning the birds' numbers, their habits, and their winter whereabouts.
So in 1979, after returning to Louisiana, Newfield obtained a banding permit and launched what she planned to be a five-year study. There was only one other hummingbird bander within a thousand miles. With the help of ornithologists like Remsen, Newfield learned anatomical terminology and measuring methods. And she experimented with nets and cages to capture the birds. That first winter, working in her own yard after the October departure of the ruby-throated for warmer climes, she banded 10 rufous and nine black-chinned hummingbirds. Since then she has banded thousands more. Over the years many of the banded birds returned. By the mid-1980s Newfield and others had extensive data to show beyond a doubt that several western species were finding good winter homes far from the Mexican hills where they were presumed to stay.
Were there simply more observers like Newfield to see birds that had been there all along? Or was there something new in the wind? "Clearly there's an increase," Remsen says. "I'd bet everything on it." Others, however, are not persuaded. Bob Sargent, a respected hummingbird bander in Alabama who learned his craft from Newfield, thinks that the birds simply went undetected for decades.
The trajectory of western birds like the rufous that show up in winter on the Gulf Coast is still a mystery. Some contend that they work their way east and then south along the Atlantic Seaboard as the push broom of winter sweeps down. Others believe they come down from the Great Lakes and the Midwest. Remsen poses what he calls the "wacko theory," that the birds follow their normal route from the Pacific Northwest to Mexico, then turn left to drift north and east to states like Louisiana. Reports of western species as far north as Massachusetts in the winter only muddy the picture. There's just not enough hard data to prove anyone right--yet.
Made up of some 350 species, the hummingbird family is one of the most diverse groups of birds in the New World. Their colors can dazzle, from the ruby-slipper red of the ruby-throated to the blue-and-green iridescence of the broad-billed. They can be as small as a bee or as large as a mockingbird. But their reputation as ethereal and gentle creatures is at odds with reality, if you listen to the humans who watch them.
"A whole subset of people see hummingbirds in the same category as fairies and angels and other mystical creatures," says Fred Bassett, a burly former fighter pilot who spends much of his time touring the country to band birds. He's particularly drawn to the varieties that summer in the West--especially the rufous, black-chinned, and calliope (only about 20 species traditionally venture north of Mexico). "But they are tough as nails. I've seen them chase people, dogs, and cats." Put out just one feeder in your yard, and a single hummingbird is likely to dominate, aggressively protecting the turf. Some species, like the buff-bellied, seem far from angelic. Says Remsen: "These are not tropical wimps."
The hummingbirds' small size--they typically weigh between three and six grams--is not to be confused with fragility. They flourish in the chilly highlands of the Andes, the tropical lowlands of Central America, the deserts of the American southwest, and the damp chill of the Alaskan coast. Some stay put; others migrate. Some, like the rufous, when they do migrate, fly as far as 5,000 miles from their winter homes to their nesting grounds. Their famously fast metabolism--the fastest of any animal in nature--makes for a constant and voracious appetite that puts a premium on moving. They are expert at snatching flies from spider webs, gorging on swarms of gnats, and of course, sticking their specialized beaks into flowers to suck nectar. One species in the Andes has a beak longer than its body. They have record hovering capabilities, and they can fly forward, backward, sideways, up, down--even upside down.
A day after the fierce storms have moved out of the Gulf Coast, Bassett is carefully untangling birds from nets on an Alabama barrier island a couple hundred miles east of the Owens yard. It is spring migration, and in the aftermath of the storm the nets are filled with an array of colorful bird species--including the occasional ruby-throated--exhausted from their 12- to 20-hour nonstop flight across the Gulf. He insists--and other hummingbird aficionados agree--that the creatures are not just aggressive; they are also smart. Bassett says that if he has let the feeder in his yard go dry, there are some hummers that will knock angrily against his kitchen window, trying to catch his eye as he gets his morning coffee. "They know who filled it," he says. "And they are as curious about us as we are about them."
But are they smart enough to outwit the potential disruptions posed by human development and a warming climate, threats that range from more ferocious hurricanes to dwindling habitat?
As with most topics concerning hummingbirds, there's more heat than light, in part because each species has its own special relationship to the environment. Rufous populations have fallen by more than half in the past 40 years, from 12 million to 5 million birds, according to Audubon's Common Birds in Decline report, largely as a result of logging and development of their breeding areas in the Pacific Northwest and their wintering grounds in Mexico. But if there is an increase among western species in the eastern United States, as Newfield and Remsen believe, it could be a sign that they are finding alternative migration paths and habitats. Whether that change might be due to more food or a temporary variation in the Gulf Coast climate is unclear.
A quantifiable shift in migration offers an exciting opportunity, says Scott Weidensaul. The boyish-faced bird bander and author is taking a break at the same Alabama site where Bassett is gathering spring migrants. Crouching on the sandy ground, Weidensaul says the potential shift of the rufous and others "shows the surprising degree of plasticity in bird migration--that's a hopeful thing given the decades ahead of us."
Weidensaul notes that the blackcap warbler traditionally migrated from central Europe to the Iberian peninsula, then south across Gibraltar to Africa. But since the 1950s British birdwatchers have observed an increase in blackcaps wintering in the British Isles--something rarely observed before. Today an estimated 10,000 blackcaps swarm to Britain rather than Africa. For years researchers wondered whether this shift was due to chance, environmental changes, or an alteration in the birds' genetic code itself. German and U.K. scientists finally resolved the issue when they caught 40 "British" birds and bred them with one another, while doing the same for birds that wintered in Africa. When given the chance to fly, the "British" blackcaps headed for London, while the others went in the direction of Madrid. Today Britain's milder climate, increased food sources, and lack of competition make it a smart destination for blackcaps, which passed on that information encoded in their genes.
Weidensaul suspects something similar may be taking place with western hummingbirds. Several centuries ago any that strayed too far east in the winter encountered dense forest cover and colder winter temperatures. But those conditions have been superseded by a plethora of gardens and feeders that increase the probability that errant birds will survive. "Once a death trap for hummingbirds, the suburban Southeast is now a land of milk and honey," he writes in his 1999 book Living on the Wind. That's true, however, only for the tougher western species, like the rufous, which can put on a gram of fat in a day. Before migrating, from 25 percent to 40 percent of their body weight is typically fat, which they will burn over the vast distances they cover. They can survive temperatures below zero degrees Fahrenheit by dramatically slowing down their metabolism. Such freezing temperatures, however, are likely to kill off any ruby-throated hummingbirds, which don't have to live through extreme temperature as consistently as some of the western hummingbirds do.
Back in the Owens yard, Newfield files down a band that is too large for her latest captive, as it lets out a plaintive cry from a cloth bag. "This is really all bookkeeping," she says, gesturing at her data notebook. "It's important that I like to catch them--but not worth a damn if you don't do something with it."
Despite decades of meticulous data gathering, Newfield expresses some intrigue. "We are finding questions, not answers," she says, slipping the custom-altered band on the tiny leg and frowning as she adjusts it. "It's complicated." Both Newfield and Remsen are skeptical of those who want to point the finger at human-induced climate change to account for the potential shift in hummingbird migration.
"Everyone wants to blame everything on global warming," says Remsen later that day in his cluttered office at LSU behind the Museum of Natural History. "It is tempting to believe, but the link is tenuous." He notes that in the past few years there has been a drop in counts among the more western species in the area, despite relatively mild winters. That may have to do with Katrina effects or specific conditions--drought, for instance--at a breeding ground thousands of miles away rather than a long-term global trend. And despite the increasing numbers of western species counted in the Southeast during winters in the 1980s and 1990s, the overwhelming majority of the birds remain true to their ancient migration path, which stretches from Mexico to Alaska. "It is
really hard to make any inference in a population when you are focusing on a peripheral area like the Gulf," he adds.
There also is a lack of hard data on the status of the Mexican wintering grounds. Though habitat destruction there is frequently cited, Remsen says it remains unclear whether that could be forcing some birds north and east. "You could go either way--there is a loss of habitat or they are doing so well they need to migrate to find greener pastures," he says. And areas considered degraded by humans--that is, fallen trees and debris--can be rich habitats for many hummingbird species.
It may be surprising that despite the intense focus on hummingbirds in recent decades, there is not even a consensus on what they eat. Some argue that the bulk of their calories come from insects; others say from nectar. Such a prosaic detail matters if you want to pinpoint the role of feeders in hummingbird migration. "It's not what we know that is so striking," says Sargent, who is busy at work with Bassett and Weidensaul gathering and banding migrating birds in Alabama. "It is what we don't know."
That mystery continues to power this small group of hummer lovers. "None of us would have been doing this if it wasn't for Nan Newfield," says Weidensaul. Here in the Owens yard, the banding is done for the morning. Three decades after starting her five-year-project, Newfield is grayer and more solid but no less passionate. She recalls a recent trip to Cuba, where she spotted the rare bee hummingbird. "It was one of the high points of my life," she says. Then, shyly, Newfield pulls out two pictures. The first is of her two-year-old grandson. And the second? A rare hybrid hummingbird.
This story originally ran as "The Drifter" in the March-April 2010 issue of Audubon magazine.