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Field & Street 

We've been having our own predators' ball in northern Illinois during the past couple of weeks. We've got our usual winter owls, of course. A snowy showed up near McCormick Place just before Christmas, and there have been reports of long-eared owls as well.

And we've got falcons galore. Our resident peregrines can be found along the lakefront. A few merlins have been sighted, and we have our usual clouds of kestrels. But the big news is at a nuclear power station in LaSalle County. There, around Christmas day, were a prairie falcon, a western bird that rarely ventures this far east, and, most exciting of all, an immature, gray-phase gyrfalcon, a bird of the arctic that has only been reported in Illinois 17 times.

The gyrfalcon is the largest of the falcons, a bird as big as a red-tailed hawk, a hunter capable of going after a flying goose. In the days when falconry was the favored hobby of the nobility in Europe, the gryfalcon was the highest ranking bird in the sport. Only members of royal families were allowed to possess one. The name is believed to come from a Low Latin corruption of hierofalco, "sacred falcon."

Its great size was doubtless a major attraction for falconers, but rarity must have contributed to its special status. Its winter range in Europe included England, Scandinavia, and Russia, but left out France, Germany, and the rest of western Europe. Its summer range on the tundra would have been out of reach of all but the most intrepid.

Contemporary falconers favor the peregrine above the gyrfalcon, because peregrines more commonly hunt by soaring high in the sky and then diving toward their prey at speeds up to 180 miles an hour. Gyrfalcons sometimes behave this way, and their dives--called "stoops"--may be even faster than those of the peregrine. But their usual hunting method involves flying low and making quick dives toward their quarry. This is not quite the spectacular effect falconers are after, but it is a style of hunting that fits well with the usual prey of gyrfalcons. Studies of their diets show that nearly 90 percent of their food is ptarmigans. These tundra grouse, like their more southerly relatives, spend their lives on the ground and fly only in short bursts to escape danger.

On the tundra of northern Canada or Alaska, a pair of gyrfalcons may stake out a territory of 200 square miles or more. It takes that much space to support a pair of predatory birds in arctic conditions. Gyrfalcons are sedentary. Generally only a few young birds wander south in the winter, so most of the 17 previous Illinois sightings--like the bird at the LaSalle nuclear power station-- were immatures. The combination of very low population density and sedentary habits would have increased their rarity in medieval and Renaissance Europe as well.

Kublai Khan is said to have owned 200 gyrfalcons, an enormous number in any time. Of course, the Mongols were very serious falconers. They even trained golden eagles to hunt wolves, although the eagle only struck the wolf. The human master of the eagle did the killing.

Most of our sightings in Illinois have been of gray-phase individuals. Gyrfalcons come in three color phases: dark, gray, and white. The dark birds are usually native to the stunted forests at the edge of the tundra. The gray-phase birds live on the tundra in Canada and Alaska. The white-phase birds live in Greenland and elsewhere in the high arctic.

The attraction at LaSalle is the cooling ponds, which provide an ice-free home for waterfowl throughout the winter. If we are lucky, the heavy concentration of food in these cooling ponds will keep the gyrfalcon at LaSalle all winter. If it does stick around, we can expect birders from all over the midwest--and probably the south as well--to drive to LaSalle County to see it.

The nearest nesting site for the prairie falcon is eastern Colorado, but we have seen a few of these birds every winter in Illinois in recent years. There were 17 recorded sightings between 1978 and 1987, and a pair wintered at the airport in Lawrenceville for several years.

Birders who have already gone to LaSalle County also report northern harriers, red-tailed hawks, rough-legged hawks, and lots of kestrels around the cooling ponds. The ponds seem to be like African water holes. They attract the herbivores, and the herbivores attract the carnivores.

Midwinter is always the peak season for owls in this part of the world. We have three resident species--the great horned, screech, and barred--that are here year round, but in winter we also get snowies, long-eared, short-eared, and saw-whet owls.

The lakefront and Lake Calumet are both good places to look for snowies. They are tundra birds, and they like open spaces. Rats and other small mammals are their major food.

Both long-eared and short-eared owls are considered endangered species in Illinois. Certainly they are possible nesters in this part of the state, but I don't know of any reports in recent years. The short-eared is a bird of wet prairies and marshes, and before farmers decided they needed to plow every inch of their land to make a living, this bird may have been the most common nesting owl in the state. The long-eared roosts in woodlands, although it may hunt in woods or open fields. The short-eared is a crepuscular species, which means it prefers to hunt at twilight and dawn. The long-eared is more strictly nocturnal. Both of these birds are medium-sized owls who favor mice, voles, and other small mammals as food.

The saw-whet is a tiny thing, shorter than a robin, but with the basic beer-keg build typical of owls. This is a North Woods species, although there is a steady succession of reports of birds in northern Illinois in the summer. The reports tell of both adults and young birds, but somehow nobody ever finds a nest. I suppose you could get famous among birders if you could find conclusive evidence of saw-whet owls breeding around here.

Saw-whet owls are hard to find, but ridiculously tame when you do find one. They like to spend the day roosting in evergreens, and I can report from experience that you can spend hours searching a small patch of ornamental yews where a saw-whet is known to be and never find the bird. If you do find it, it may let you pick it up and hold it for a while without offering any resistance or attempting to escape. At least, that is what people say.

Our resident owls will be getting noisy and conspicuous during the next few weeks. Owls defy the elements by nesting in midwinter. A great horned owl will incubate its eggs through the coldest nights in January and find enough food to raise a brood of young birds in late winter, when everything else in the woods is struggling to make it through until the new growth starts in spring.

This habit of nesting at the least hospitable time of year always seemed almost perverse to me until I read a recent article in the New Yorker by Elizabeth Marshall Thomas. Writing about lions, she noted that hunting lionesses take their half-grown cubs with them on the hunt. House cats and other predators that take tiny, inoffensive creatures like mice can take live prey home to the kittens so the young can practice capturing and killing the animals they will hunt when they grow up. But lions kill big dangerous animals such as wildebeests and elands. They have to kill quickly to avoid getting hurt, so they can't bring home a demonstration animal for their young. The cubs have to learn by watching.

Owls don't usually take dangerous prey, although great horned owls will sometimes capture house cats and weasels, but their young do follow them around for months after leaving the nest. They don't go out on their own until fall. Maybe by nesting in January the owls can give their young several months of instruction in how to sneak up on a deer mouse. You can observe a lot just by watching, Yogi Berra is supposed to have said, and maybe the owls do just that.

Sometime in the next couple of weeks, I'll be starting work on my 1991 breeding-bird survey for Somme Woods. Last year I didn't get going until April, so I missed my best shot at finding the local owls. If there are any birders out there willing to get cold, wet, and mosquito bitten in the cause of science, I'd like to hear from you (at 583-2046). I could use help anytime between now and the middle of July. The more people we get involved, the better our chances of finding all the birds of Somme.

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