The fabled Gyrfalcon wanders south from its northern haunts every winter, and sometimes it pursues its prey right under our noses
Published: October 21, 2011
|I was walking along a woodlot bordering on small winter fields on Vancouver Island, a few miles east of the capital city Victoria, when the click of claws on wood made me stop. |
A large raptor had just alighted on a bare maple branch. The bird returned my stare, allowing me time to focus my binoculars on the bold heart-shaped dots that marked its whitish chest and belly.
I was thinking Peregrine but saw no black cap or prominent bar on the side of the throat, just a narrow stripe bordering the cheek and accentuating dark eyes.
Then I considered the bird’s large size, and it dawned on me: This was a Gyrfalcon, the largest of all falcons, the falconer’s favorite.
Stocky, powerful Gyrfalcons make their home all around the top of the world, breeding in Greenland, Iceland, Norway, Finland, and Russia, as well as North America. Here their breeding range is restricted to Alaska and northern Canada; the closest known nest sites are roughly 700 miles up from the U.S.-Canada boundary.
The falcons are fabled hunters that eat an assortment of birds, including gulls, seabirds, and waterfowl, as well as small mammals, but their principal prey is ptarmigan, which they typically drive to the ground after exhausting, sustained, level pursuits.
In winter, when the weather turns brutal and sunlight becomes scarce, Gyrs migrate. Adult males mostly remain within the southern part of the breeding range, but adult females and immature falcons fly farther. They may show up anywhere across the northern United States, and they have been recorded on Christmas Bird Counts as far south as Oklahoma, but sightings and recoveries of banded birds have been reported most often from coastal areas, such as Vancouver Island, where I was.
When I stepped back for a more lateral view of the falcon’s wings and tail, I inadvertently flushed a cock pheasant from a ditch. The bird thundered out of the reeds, and the Gyr went after it immediately. But the open landscape required for a successful hunt was in short supply. Just before the game bird was overtaken, it reached the opposite side of the field and dashed into the woods.
I visited the area often in ensuing days, and I again spotted the Gyrfalcon perched on a prominent tree. Hoping to see more action, I deliberately flushed ducks from the ditch or a nearby irrigation pond. As expected, the falcon started after them, though without success.
After a number of meetings, the falcon seemed to anticipate the opportunity. To get a head start on fleeing prey, it flew toward me when I entered the field. Then it perched and waited for me to flush waterfowl. But the Mallards, Buffleheads, pintails, and teal refused to rise. Apparently, they had become wise to the risk. As soon as they saw me approaching, they rushed to the farthest side of the pond and stayed put.
For me, an independent wildlife researcher fascinated with falcons, and especially Gyrfalcons, the experiences were invaluable. I have traveled across Canada and Alaska on a quest to learn about their hunting tactics. My observations have not only yielded an article in a leading scholarly journal but also taught me that much remains to be learned about the charismatic and surprising Gyr.
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WHERE GYRFALCONS ARE SEEN IN WINTER
Over the last 11 Christmas Bird Counts, Gyrfalcons have been recorded four or more times in 24 count circles in the United States and Canada. The Google map above plots the 24 count circles (blue markers) as well as the 20 southernmost Gyr sightings (red markers) of the last 11 counts. Click the map to see it in a new browser window, and click the blue and red markers for more information about the sightings.
Note: The Christmas Bird Count is held annually over a period stretching from the last month of one year to the first month of the next. For this reason, Audubon doesn’t refer to counts by year. Instead, it refers to counts by the order in which they occur. The last count, conducted from December 14, 2010, to January 5, 2011, was the 111th. This year’s will be the 112th. More info: http://birds.audubon.org/christmas-bird-count
Gyrfalcon every day
Based on my experience, I can say that the best location to find the falcon is the Bow River downstream of Calgary, Alberta. Warmed by municipal effluents and sewage-treatment plants, the water stays unfrozen even when the temperature plunges below zero for weeks on end. No matter how polluted the river may be, it represents a winter refuge for hundreds of Mallards too lazy or unwilling to migrate south. They in turn attract Bald Eagles and Gyrfalcons.
Local experts see Gyrs around Calgary practically every winter day. The best method of spotting one is to drive the country roads south and east of the outskirts, checking power poles and keeping a lookout for flocks of ducks. Departing from the river, the Mallards set course for certain farm fields to feed on spilled grain. When flocks rise in a panic, scan the sky behind them. With luck, you may pick up an attacking falcon.
My first sighting of a Gyr dates back to 1959. A recent immigrant to Canada, I went for a drive around Calgary’s desolate, snow-covered farm fields. The unexpected reward was a Gyrfalcon in hot pursuit of a big white jack rabbit. Each time the falcon stooped, the hare jumped up, meeting the attacker in mid-air and sending snow flying. The falcon pulled up at once but repeated its attack half a dozen times. The chase went on and on, and ended only when the hare reached a fence line and took shelter under the strands of barbed wire.
The following summer, I made a three-month journey to Alaska. Along the way, I kept an eye out for Gyrs. A good place to see them was (and is) along Yukon Highway 3/Haines Highway, the connector between northern Canada and the Alaskan town of Haines, near the famous Chilkat Bald Eagle Preserve. Gyrfalcons that nest in this high mountain country make ptarmigan their regular fare, but they also take rodents.
As luck would have it, a falcon picked up a ground squirrel on the road right in front of my car. Elsewhere, while canoeing the wide Yukon River, I occasionally spotted Gyrs soaring over the hills or having a game with a group of ravens. Once, when several ducks flushed from the water ahead of my canoe, a Gyrfalcon swooped down from the cliffs. The ducks narrowly saved themselves by splashing back into the water.
Much later, I moved back to Alberta and settled in Edmonton, some 200 miles north of Calgary. At that high latitude, winter is six months long, and an estimated one thousand hardy Mallards survive only because a section of the North Saskatchewan River just downstream from the city stays open.
To find food, the ducks have to venture out over the frozen stubble. If the snow deepens, they become dependent on area farms where beef cattle are fed with silage or grain. The ducks visit favorite sites daily.
As soon as birders report Gyr sightings on the Edmonton hotline, interested residents and visitors zero in on the cattle farms. During some winters, Gyrfalcons are scarce; in others, four or five may be active. I took advantage of the good years, watching every day unless it was snowing or extremely cold. During weekends, I met up with photographer Gerald Romanchuk and raptor expert and Alberta Fish and Wildlife Division biologist Gordon Court. (Court’s name should be familiar. His fascinating articles on Peregrine Falcons and on Snowy and Great Gray Owls appeared in this magazine in June 2008 and December 2010, respectively.)
Taking ducks by surprise
In 2003, I published a paper with Court in the Journal of Raptor Research detailing 70 Gyrfalcon attacks on ducks around the cattle farms, of which 16 were successful. In just over half of the successful hunts, Gyrs tried to take ducks by surprise. Approaching low in the cover of bushes or buildings, the falcons attempted to seize their prey just after it had flushed or even before it had a chance to get off the ground.
When they caught something too heavy to carry away, the falcons plucked it where it fell; curious steers sometimes surrounded the feeding falcon. If the snorting bovines approached too close, the falcon left, coming back later to finish its meal or to capture another duck.
The Gyrfalcon’s stealthy foraging tactics are described well in the professional literature, but I found no reference to a much more spectacular hunting method. I was able to observe it many times by keeping my telescope focused on a perched falcon for as long as it took to see it take off.
If no ducks were at the feed lot, the Gyr seemed content to watch quietly from a fence post within view of the farm. Then, well before I saw ducks flying in from the river miles away, it locked onto them using its superior sight. As soon as it spread its wings, I put the telescope aside and picked up my binoculars.
Keeping the falcon in my glasses, I watched as it accelerated and climbed, diminishing in size. My heart skipped a beat when finally I discerned the line of ducks, tiny specks vibrating against the winter sky. Aware of the approaching danger, the flock broke up and veered out of the way, while the falcon singled out a target. Closely pursued, some ducks were seized in the air. Others descended to find cover on the ground.
The Gyrfalcons outflew and forced down any Mallard they pursued with persistence. How successful they were in securing downed ducks varied from falcon to falcon. Some tackled the prey without hesitation; others swooped several times in a futile attempt to flush it out of hiding. One falcon proceeded on foot over deep drifts to search for a duck that had taken cover under bushes. Having landed on the shoulder of a highway, one Mallard drake put up an effective defense, lunging with gaping bill each time the falcon made a pass at him.
Adding to the drama were Bald Eagles that shadowed the Gyrfalcons. One or more adult eagles, wintering along the same open stretch of river, often perched on trees within view of the feed lot where the Mallards gathered. Soon after a falcon began plucking its kill, the eagle would commandeer the carcass. If a falcon failed to catch a duck and flew away to hunt elsewhere, the eagle followed at a distance, searching the fields.
Prey theft by Bald Eagles was also commonplace near Calgary and particularly in the Fraser River Delta near Vancouver. The naturalist and photographer Miechel Tabak has seen more than a dozen instances in which Gyrfalcons were robbed of just-caught ducks. To guard against such piracy, the local Gyrs have become adept at hunting low over the fields and along the ditches.
Is the Gyrfalcon equally as adept at catching pigeons? In Arthur Cleveland Bent’s classic handbook Life Histories of North American Birds of Prey, a member of a crew sailing in the Canadian arctic in 1910 reported that Gyrfalcons violently pursued the ship’s messenger pigeons but captured none. The conclusion was that pigeons were more than a match for a Gyr. So when birders in Edmonton reported some years ago that a Prairie Falcon and up to four Gyrfalcons, adults and immatures, were hunting pigeons in a downtown granary complex, I leapt at the chance to see for myself.
Sitting for hours in a car on a snow-covered parking lot, often with the engine kept running when overnight temperatures plunged far below freezing, I discovered that Gyrfalcons were more than capable of catching pigeons, and that the adults did so by a method never before described in the scientific literature and quite different from techniques used by the Prairie Falcon, an adult female.
The lot was situated between a busy highway and a railway, and the train tracks were straddled by a loading silo that was home to 500-600 feral Rock Pigeons attracted by spilled grain. Their frequent flushing signaled to me that they had seen the enemy. As soon as they exploded upward, I craned my neck, hoping to spot a falcon before its hunt was over. Over 44 days, I tallied 141 attacks by Gyrs and 104 by the Prairie Falcon. They captured 15 and 27 pigeons, respectively. This means that the Prairie was about twice as successful as the big Gyrs.
A primary objective of both falcons was to take the pigeons by surprise. Approaching at great speed low over the railway or between the buildings, the Gyrs grabbed six birds just after they flushed. The Prairie nabbed eight pigeons in similar surprise attacks.
After the panicked pigeons had taken to the sky and were careening back and forth in dense globular flocks, I noticed an interesting difference in hunting styles. Soaring high above them, the Prairie took its time to select a specific target on the outside of the group. Then, keeling over with furled wings, it stooped like a falling stone, seized its prey at once, and carried it down to the snow-covered ground.
By contrast, the adult Gyrfalcons attacked from below. They descended fast, beating their wings to increase speed. Then, using their momentum, they swooped steeply upward into the middle of the flock. Their objective was to grab a pigeon at random. If the strategy failed, the Gyr would repeat the maneuver, rising and falling like a pendulum. The behavior contrasted sharply with that of the immature Gyrs, which took it easy. They searched the lower roofs of the granary complex for pigeons that died after hitting the air circulation fans or being struck and wounded by other falcons. Carrion feeding is a common trait of the Gyrfalcon, a practical adaptation to lean times in its harsh northern environment.
Gyrs at sea
So, too, apparently, is spending extensive periods of time at sea. That’s the surprising recent discovery of researchers working at Gyrfalcon breeding sites and a banding station in Greenland. Between 2000 and 2004, they outfitted 48 Gyrs with satellite transmitters and then tracked their movements.
The results, published this summer in Ibis, the quarterly journal of the British Ornithologists’ Union, revealed for the first time not only that Gyrfalcons from Greenland spend much of their winters on sea ice far from land, but also that the falcons fly directly west across the ocean to Canada and then migrate south along the east coast of Ellesmere, Devon, and Baffin Islands. One tagged falcon even reached the northeast coast of Labrador.
Gyrs from Greenland’s east coast, where sea ice builds inexorably throughout the winter, roam much more widely than birds from the west coast. The researchers theorize that the falcons are pursuing seabirds and ducks that the ever-widening ice pushes farther and farther away from the mainland. One east-coast bird spent almost a month along the ice edge between Greenland and Iceland. Another, a juvenile female, spent more than 40 days over the open ocean and sea ice.
How far Gyrs roam appears to depend not only on how abundant the local food supply is but also on how territorial each falcon is. “Individuals with small winter home-ranges, which probably have an abundance of food, are dominant and drive off other Falcons,” write the researchers, ornithologists Kurt Burnham and Ian Newton of Oxford. “Individuals that are not able to establish small winter home-ranges are left to wander.”
Juveniles, the authors conclude, may have to give way to adults and, in extreme situations, may be forced out over the open ocean or sea ice or even longer distances. “It could be such individuals that occasionally turn up well south of the usual range in winter, including the northeastern USA and the British Isles.”
Dick Dekker has a Ph.D. in wildlife ecology. He wrote Hunting Tactics of Peregrines and Other Falcons and other books.||