Reader Dominic has called my attention to two new reports from the BBC about the gyrfalcon (Falco rusticolis), pronounced “JER-falcon.”
First, a bit about the bird. It’s the world’s largest falcon, with some specimens reaching three pounds with a four-foot wingspan. They’re magnificent birds:
Photo by Doug Backlund; go to his page for many more great photos of the bird
Here’s the range map from Cornell’s All About Birds; they breed on the North American tundra but range widely south. A map of its worldwide distribution, including Greenland, northern Europe and Asia can be found here.
They’re bird eaters; the Cornell site reports that they “eat mostly ptarmigan, but many other prey species have been recorded, including fulmars, gulls, jaegers, ducks, geese, Rough-legged Hawk, Short-eared Owl, sparrows, buntings, and redpolls.” Here’s an amazing video of one taking a ptarmigan on the wing: the strike occurs at about 2:15 (I find the music annoying; you might want to turn it off).
So what’s new about the bird? Two discoveries, both made by a team headed by Kurt Burnham, a Ph.D. student at Oxford’s Edward Grey Institute of Field Ornithology.
1. The gyrfalcon is basically a seabird. As the BBC reports, up to now its hunting habits during the nonbreeding season—the winter—were largely unknown. But tracking the birds with radiocollars shows gyrfalcons to be “secret seabirds”:
Gyrfalcons living in the high Arctic overwinter out at sea, spending long periods living and hunting on pack ice.
It is the first time any falcon species has been found regularly living at sea.
The birds likely rest on the ice and hunt other seabirds such as gulls and guillemots, over what appears to be one of the largest winter ranges yet documented for any raptor.
“I was very surprised by this finding,” said ornithologist Kurt Burnham who made the discovery. “These birds are not moving between land masses, but actually using the ice floes or pack ice as winter habitat for extended periods of time.”
“Previously, all species of falcon were considered to be land-based birds.”
. . . Those on the east coast ranged far more widely, covering between 27,000-64,000 square kilometres. Some of these had no obvious winter home ranges and travelled continuously during the non-breeding period, spending up to 40 consecutive days at sea.
During the winter one juvenile female travelled more than 4,500km over 200 days, spending over half that time over the ocean between Greenland and Iceland.
2. Some gyrfalcon nest sites are ancient. Another report, from BBC EarthNews, shows that the nesting areas used by these birds can be several thousand years old. Like other falcons, gyrfalcons don’t build nests, but simply scrape out an area on a rock ledge. New research shows this:
Carbon dating revealed that one nest in Kangerlussuaq in central-west Greenland is between 2,360 and 2,740 years old, the researchers report in Ibis.
Three other nests in the area are older than 1,000 years, with the youngest nest site first being occupied 520 to 650 years ago.
These ancient nests are still being regularly used by gyrfalcons.
“While I know many falcon species re-use nest sites year after year, I never imagined we would be talking about nests that have been used on and off for over 2,000 years,” says Burnham.
They also carbon-dated some gyrfalcon feathers to over 600 years old. But these aren’t the oldest continuously used nesting sites by birds, not by far:
By carbon dating solidified stomach contents, peat moss deposits and bone and feather samples from various moulting sites, researchers have in the past shown that colonies of snow petrel have returned to the same sites for 34,000 years and adelie penguins for 44,000 years.
Wow. Two amazing things we never knew about these amazing animals.
I’ve seen a couple in captivity, but never in the wild. (I guess I should spend more time on the artic ice.)
They are stunning birds. Make sure you take a good snow jacket! The problem for the falcons is diminishing sea ice & dimishing rages for the prey, as with polar bears.
Just what I was thinking– that melting sea ice would mean loss of hunting range for them.
Diminishing… I really am hopeless!
I notice that when banked in a turn & observing the ground ‘she’ keeps her eyes parallel with the ground [draw a line from one eye to the other & it remains constantly at 90 degrees to the up/down axis]
I fly gliders & I don’t do this when turning into a landing approach. I keep my eyes in the frame of reference of the glider [a line through the eyes remains more-or-less parallel to the wings]. If I did what the bird does it would be very disorientating (in fact nauseating). Wiki says that bird & mammal inner-ear balance sensors are basically the same so I can’t figure out how/why she does this, but she must know best !
I wonder why her wing-tip feathers are black ?
In hand, raptor banders often demonstrate the amazing difference between birds and mammals, when it comes to this gyroscopic behavior that all our hawk species have. When shown, the human jaw drops… on the nine year old as well as the those in their nineties.
With any hawk, banded and about to be released back into the wild, the bander holds the bird safely — like a jar or a tube of something. At this point if you move the hawk up and down, turn it left, right, whatever, at random: the head seems utterly detatched from the body! It remains stationary.
Now hold the bird horizontal, as if in flight, and lightly bounce it up and down and roll it a bit, even move it quickly once (for a last effect), and the head remains still.
While all our raptors, hawks and owls, have this, it is especially handy if you are a falcon or accipiter species chase down prey items that also have wings (and know how to use them). In mammals, you can only get a glimpse of this in cats even when their walking gait quickens. At full throttle, but shown is slow motion, wild cats have this stillness. Humans, not so much.
Last, but not least, this adaptation is part of a whole. I mention this as many old school naturalists like to teach by dissection even when holding a living, whole, wild thing. Unfortunately, by example, they have passed this Parts Dept. approach on to younger scientists.
So to put it another way: this is a professional Gyrfalcon; this is what they do for a living, so kids, don’t try this at home. And, by extension… no, that lustrous wood steering wheel will not make you a better driver, nor will that set of irons make you a better golfer. It is about the whole package. Insert “evolutionary” and/or “ecological” here.
Great reply ! But the motions you are talking about do not involve a banking turn (I don’t think)
If a human kept his eyes (& therefore the ears) in a horizontal plane in the way that she does he would get dizzy because the fluid in the canal would ‘slosh about’. How is it that she doesn’t have this problem ? By keeping her head horizontal in a turn the fluid in her ear canals will ‘slosh’ as she enters & exits the turn. Humans overcome this by keeping the ‘ear plane’ aligned at right angles to the apparent direction of weight in turns.
It suggests that you can’t ‘dizzy’ a Gyrfalcon
@ SnowyOwl
As Michael Fisher said, great reply! Also, great blog–bookmarked. Any chance you’ll resume posting?
Is this related to birds not being able to stabilise the visual field on the retina very much by moving their eyes, so they rely on keeping the head stable?
Wow is right! That was some amazing film footage o.O What a beautiful raptor– I’ve never seen one (except in photos).
Wow indeed!
I occasionally get the miniature engraved version on packages: http://colnect.com/en/stamps/stamp/52349-Gyrfalcon-Sweden
I had the wonderful privilege of watching a fight between a pair of Gyrfalcons and a pair of Parasitic Jaegers (Stercorarius parasiticus) at Alexandra Fjord on the east coast of Ellesmere Island, a couple of years ago.
The Gyrfalcons were white (with some small grey marks on some feathers), and the Jaegers were mostly black; at a distance and against the bright white background of the overcast sky, the fight was between two snow-white birds and two jet-black birds. The Jaegers had the upper hand, pouncing on the pair of falcons while they were cruising slowly near ground level – perhaps the falcons were searching for tasty morsels such as Jaeger chicks, though it was too late in the season for such chicks to be helpless non-flyers.
Once the fight started in earnest the Jaegers maintained their advantage through what appeared to be better coordination between the pair – the falcons basically scattered, but the Jaegers concentrated their attacks on one falcon at a time. This allowed the second falcon to land and rest for a minute or two at a time, though after the first few cycles of 2-on-1-then-switch-targets, the falcons seemed to figure out that hard climbing for altitude and maneouverability was a better option. The fight was unresolved when they moved beyond my visual range, wheeling around a headland about 2 kilometres to my east.
From what I could see of the behaviour and relative flying abilities of each species, I’d wager a falcon would win a straight 1-on-1 fight more often than not – the falcons could turn tighter, accelerate faster, and were willing to roll completely inverted at times, but the Jaegers were better at maintaining their momentum and had a longer reach with their beaks than the falcons had with their talons. I got the impression the Jaegers were happy to keep the fight at low altitude, where they might have had an advantage dodging obstacles (large boulders) compared to the skidding falcons.
Gyrfalcons are primarily visual hunters, aren’t they? If they overwinter in the High Arctic they’d have to deal with several months of complete darkness – do they at least move south of the Arctic circle in winter?
Yes, as the range map indicates, at least some gyrfalcons move southward in the winter. I took a winter birding trip to Sault Ste. Marie a few years back, and got to see my “lifer” gyr perched on a hydro plant. The outlet was about the only open water for miles around, and had attracted some pretty hardy waterfowl, including Common Goldeneye and Common Eider (also a lifer). Sure glad the gyr didn’t eat the eider till after I’d gotten to see it!
Very cool thread! Thanks JAC & Dom, and everyone who’s added their own cool insights/experiences.