Rigor Vitae: Life Unyielding

Wednesday, January 18, 2006

VISITORS FROM THE NORTH

A cubic yard of dilute desert mud percolates into my back yard as the washing machine works a first load of laundry downstairs. A little winter camping trip in western Utah has come to an end.

For two days and nights I scouted the Rabbitbrush-dotted lowlands of my state's left margin, not far from the Dugway Proving Ground, where NASA's Stardust return capsule and its cargo of cosmic debris fell to earth early Sunday Morning. I missed the canister's descent, though my eyes were trained skyward for much of the day.

Over fifteen winters I spent a ridiculous amount of time here, flying falcons at ducks flushed from numerous small springs. The area is rich with birds, but the most conspicuous winter residents in those days were the Rough-legged Hawks (Buteo lagopus). Their odd, kestrel-like hover was a common sight: big bicolored, bullseye wings flopping incongruously as their pilot hung stationary, scanning the prairie for voles. From nearly every power pole they watched us. As I carried my falcon away from the scene of a kill, a Roughleg inevitably flew out to investigate the site.

Natives of the barren tundra, the birds were often amazingly tame. When I was sixteen, I caught a large hen with my hands, and no raptor was easier to trap—that is, if you had a mouse for bait. Prey as challenging as a tethered sparrow was consistently ignored. In the hand, they were astonishing: huge, but insubstantial—all feathers. Their ridiculous, tiny feet contrasted with their oversized, kite-like heads, which bore big, beautiful eyes and a slender steeply-curved bill.

Over the past four years, I've noticed a dearth of the once plentiful birds, so this trip found me particularly attentive, scoping every distant Raven and Redtail to confirm its ID conclusively, but not once did I glimpse my polar Godot.

Roughleg populations are said to fluctuate with those of their main summer prey, lemmings, but a cursory scan of recent Christmas bird count data reveals no glaring nearctic decline. Perhaps the recent mild weather has failed to drive them this far south, although this year has treated much of the country to an irruption of Snowy Owls, another lemming-eater. The phenomenon of bird migration is filled with mystery.

Around here, Dark-eyed Juncos (Junco hyemalis) are emblematic of winter. Spring has not officially begun if one can still view their executioner's hoods and long, white-edged tails. I can't explain how they do it, but I see my first juncos of every season on the first truly cold morning, as if the birds had dragged the weather right into the yard behind them.

No brumal visitor is more exciting to see than a Gyrfalcon (Falco rusticolus), largest of the falcons. I was nineteen when I saw my first confirmed Utah Gyr, in this very area. I had driven out here before dawn to retrieve the Prairie Falcon I had lost the previous evening. Once it was light enough to see, I tossed a jessed pigeon into the air and called my bird. A weighted drag attached to the jesses allowed it to fly but a few yards. I scanned the horizon and sighed with relief when I saw a distant falcon flying hard toward me. As the bird got closer, I saw that its wingbeat was too slow to belong to my Prairie. I realized it was a wild Gyr just in time to save the pigeon, which stood a mere 20 feet from me.

Since that heady day, I have seen a number of winter Gyrfalcons, and trapped two, both of which were young birds in very poor health. I kept them for a few days, fed them up and released them, but I'm quite certain that neither of them are with us today. I assume that any wild Gyr I see this far south is in a similar state, although there are those who disagree with me, and I recently saw one in central Wyoming that looked like an adult.

Piecing together the complex puzzle of migratory bird behavior is a challenge, especially since most of us are limited to working with a handful of anecdotes. Your personal anecdotes, views and comments would be welcome aids to the task.
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illustration: SILVER GYRFALCON PORTRAIT (2005) Acrylic 15" x 7"

2 Comments:

Anonymous Nigel said...

Hi Carel,
well you have opened a very complexed can-o-worms! There are those that believe they have the answers, all wrapped up in a pretty package. My beliefs on migration is based on rule # 1............there are no rules!
In a general overview birds migrate due to weather, food supply and photo period. These are triggers that stimulate a response. Some species choose to respond , while others don't. In fact some individuals of a single species choose to act on these or ignore. Lets take Cooper,s hawks in southern Ontario as an example, following the books and literature, immys move out first, followed by adults and sub-adults next. Then why are immy birds feeding around my feeder here, in the middle of Jan. and others are in Georgia ?
To support the theories, all the Great grey owls banded, seen or found dead last winter in Wisconsin and Ontario, were in fact adults, proving the main prey species dropped off before breeding season and stimulated a mass movement south. That being said, who was on there breeding/winter territories to say all left??
There are to many variables that exist to make "carved in stone " predictions.
Next time we cross paths we can have an in depth discussion, over a pint!!
(a couple of my "thoughts" on migration)

bye for now,

Nigel

9:08 AM  
Blogger cpbvk said...

Looking forward to that pint, Nigel!
Nice to hear from someone who's trapped far more raptors than I have. My sample of two Gyrs is admittedly meaningless, and since my post I've received emails about numerous healthy Gyrs trapped in my region. On reflection, my assertion that my sick birds were representative was probably hasty. Still, the disappearance of west desert Roughlegs has got to mean something...or more likely, a lot of little things.

4:42 PM  

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