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The extraordinary becomes commonplace during the fall migration. Casual birders often miss this because they tend to prefer May over November. In May the weather is better, and it improves through the month instead of getting worse. And the birds are all bright colors and bold patterns, feathered for the breeding season and easy to identify.

But for the serious birders, the people we might refer to as real nut cases, fall is the best time. The obscure plumages are challenges rather than obstacles. And there are more birds around. The nesting season has just ended, and bird populations are at their annual peak. Many of the birds are young that have never made a migratory flight, and a certain percentage of those are avian idiots that will never make another. They wander off course, show up in places where they don't belong, and probably won't survive the winter. But the birders are out recording their existence and testifying to their wanderings. If they are on somebody's list, maybe they didn't die in vain.

The Egyptian goose that showed up at Wampum Lake in southern Cook County a couple of weeks ago is off the charts as far as wanderers are concerned. This is an African bird that you would expect to encounter on Lake Victoria, but to see one in a small lake near the junction of the Calumet and Kingery expressways is so unlikely that we have to suspect this bird's provenance. Actually the mystery is not all that mysterious. There are hobbyists who keep and breed flocks of exotic waterfowl. Whenever we discover an Egyptian goose, a bean goose, or a ruddy shelduck running loose, we explain it as an escapee from a captive flock.

The Ross's goose at Fermilab in Batavia might have got here on its own. This bird is a smaller version of the snow goose, which we see here regularly in spring and fall. The Ross's goose nests in the high arctic and winters in the western U.S. It is regular along the Texas gulf coast, so we can imagine a migrating bird drifting a bit too far east and ending up in Illinois.

An immature lesser black-backed gull has been hanging around Montrose Harbor. This Eurasian species has recently expanded its breeding range to the north Atlantic coast of North America. Prior to the early 80s there were only two sightings of this species in the Chicago area. Now the bird has entered the "rare but regular" category.

This may turn out to be a good winter for northern finches. Many birds of the arctic and the northern forests exhibit irruptive behavior. Most winters most of the population remains near its nesting grounds. But some years large numbers of individuals come south, probably in response to food shortages that may be caused by population buildups. It is unclear how many of them make it back.

Arctic mammals also make irregular migrations in response to food shortages created by population increases. Lemmings got their reputation for mass suicide when migrating herds tried swimming across bodies of water too large for their tiny capacities.

So far the most noticeable winter finches are redpolls. They have been turning up in some numbers at Montrose, and at least one bird among them has been described as "very pale." The description does not mean the bird hasn't been getting enough sun. Instead, it reflects the desire of a birder to turn this bird from the relatively abundant common redpoll into the much rarer hoary redpoll.

Redpolls are tiny birds, smaller than house sparrows. In winter both sexes have red crowns--hence the name--and the males also show a faint wash of raspberry on their breasts. The young of the year are white with heavy streaks of brown. Common redpolls nest where the last stunted forests give way to tundra in the Arctic.

The hoary redpoll, which is paler than the common but otherwise quite similar, nests on the tundra north of the forests. According to all the standard reference works, this tiny bird regularly winters on Ellesmere and Baffin islands, which are both way north of the arctic circle. We're talking about a bird that weighs less than 20 grams after a big meal, and it manages to survive for months on end in total darkness, hurricane-force winds, and temperatures of 50 or 60 below zero. Somehow in those horrible conditions it maintains a body temperature in excess of 100 degrees.

Hoary and common redpolls are known to interbreed in places where their ranges overlap, and some authorities regard them as one species with two slightly different color morphs. Birders hate that kind of talk. They want as many species as possible so they can expand their lists. Until about 20 years ago the snow goose was considered two species. The mostly white form was called the snow goose, and the mostly dark form was called the blue goose. When taxonomists decided to lump them into one species birders howled. One man I know had spent his entire adult life building his North American list up to 600 species, a number that put him in the elite. The lumping of the snow goose dropped him back to 599.

Another northern species, the Bohemian waxwing, was recently reported near the Museum of Science and Industry in Jackson Park. It was feeding on fruit trees, as is the habit of waxwings. The closely related cedar waxwing is a common resident species in northern Illinois, but the Bohemian is a special occasion. We see them less than once a year, though when they come they may come in numbers. Floyd Swink counted 75 of them in March 1962 at the Morton Arboretum.

A northern shrike was seen in the Palos preserves being chased by robins and flickers. Shrikes are predatory songbirds. We have two species of very similar appearance in North America. The loggerhead shrike used to be a common nesting bird around Chicago, but is now on the endangered list in Illinois. The northern nests at the edge of the arctic in pretty much the same sort of situation as the common redpoll, which it probably eats. We see a few northerns here every winter.

I wonder how the robins and flickers at Palos knew that a shrike was something they should try to chase away. They can't have had much personal experience with loggerheads, since there are scarcely any of those around. And northerns are always rare. Another unsolved mystery.

Flocks of snow buntings, one numbering 150 birds, have been seen along the lakefront, and a lapland longspur was sighted at Montrose. Both of these species nest on the tundra and migrate south in the fall. To me, the arrival of snow buntings marks the beginning of winter. I always seem to see them on cold, blustery days.

If the weather doesn't scare you away from the lakefront, you might see some snow buntings either on a beach or on the step-stone revetments. They are slightly larger than sparrows, and as they fly away from you you will see lots of white. All but the tips of the wings are white, as are all the underparts, the outer feathers of the tail, and, on the males, the rumps. Their backs are tan, and the wing tips and central tail feathers are black. You do not need to be an expert birder to recognize this species.

You do need to be pretty good to identify a lapland longspur. There are four species of longspur in North America. They are all small birds that favor open country, and they all have elongated hind toes--hence the name. You will never in a million years see one of those elongated toes, since the birds spend their lives skulking around in the grass.

Breeding male longspurs are boldly patterned in black, chestnut, and buff, but we don't see any breeding males around here. We see winter birds that are variously streaked in shades of brown and very difficult to identify. Range does help the problem. A fall sighting of a longspur is almost certainly a lapland, but dedicated birders are always hoping to find a Smith's longspur (which does show up here in spring but almost never in fall) or even a chestnut-collared longspur (which may have shown up a few times but hasn't been reported in the Chicago area since 1923). During fall migration, you never know.

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