A snowy owl (photo added 2018)
A snowy owl (photo added 2018) Credit: Charles Krupa

Snowy owls have been appearing on the lakefront from from Northerly Island to Illinois Beach State Park, north of Waukegan. Nine species of gulls–including the extremely rare, for these parts, mew gull–were discovered at Michigan City. The ducks we call old squaws are diving for zebra mussels in the lake, and northern shrikes have flown in from the taiga. Winter is definitely here.

That mew gull at Michigan City should be hanging out on the Pacific coast. Maybe it got blown this way by one of the storms now submerging the far west. An ocean of air envelopes our planet, and its currents can carry the birds anywhere.

A Brewer’s sparrow continues to hang around the Lincoln Park bird sanctuary. This bird lives out in the sagebrush and shouldn’t be within a thousand miles of Chicago, especially at this season. It is a nondescript little brown job that could be picked out of a crowd of house sparrows only by someone with an experienced eye. If you aren’t into birding you probably have never heard of Brewer’s sparrow, and if you saw it you would not understand what the fuss was about. However, if you do see the bird in Lincoln Park you might be having a once-in-a-lifetime experience. The only other Illinois sighting was in 1982 in Jackson Park. It could be 50 years before we see another one.

The bird is named after Thomas Mayo Brewer, a doctor who collected bird’s eggs (his collection ended up at the Museum of Comparative Zoology at Harvard). He also enjoyed the friendship of Audubon and Thomas Nuttall, another early American ornithologist of note. If you were friends with those two you stood a good chance of having a bird named after you. Brewer is memorialized by a blackbird in addition to a sparrow.

Nonbirders would have no trouble understanding the appeal of the sightings of bald eagles at Waukegan and Hegewisch. When I started birding seriously 25 years ago you had to go all the way to the Mississippi to see an eagle. They are still something of a big deal in the Chicago area, but sightings are now in the rare-but-regular category.

The former Meigs Field–which I suppose we should start calling Edgar International–has always been attractive to snowy owls. Runways and short grass probably offer a good approximation of the tundra, where these birds spend their summers.

You can see snowy owls every winter if you go out and look for them, and regardless of your knowledge of–or attitude toward–birds, you will probably think the sight of a snowy owl is a big deal. It is very difficult to be indifferent to an owl, especially a big owl and even more especially to a big white owl with yellow eyes. Sparrows are just birds, but owls are bearers of messages from the realm of the supernatural and often omens in their own right. Flush a snowy owl from a Lake Michigan beach and watch that broad five-foot wingspan raise that heavy body from the ground, and you won’t forget it.

Nocturnal animals have a better shot at being mysterious or creepy than creatures of the day, and that gives owls a head start. Owls also have feathers of an unusual design–filigreed edges–that enables them to fly silently. An owl could fly down and land on your shoulder and you wouldn’t even know it was there until you felt the talons digging into your clavicle. Such feathers are an obvious advantage for nocturnal hunters. They help owls sneak up on their prey, and they also help them hear their prey even as they swoop down on it.

Of course snowy owls are the least nocturnal of all owls. An arctic animal that hunted only at night would have to go six months between meals.

Snowy owls nest and hunt on the treeless tundra. The most northerly nest ever found was on Ellesmere Island, at 82 degrees north. The owls seek out low ridges both as vantage points for hunting and as nesting locations. They eat a wide variety of birds and small mammals, with lemmings the most common item in their diet. Audubon saw them catching fish, which they did by lying down at the edge of the water and waiting for a fish to get close enough to hook with one taloned foot.

Lemmings are among the northern animals subject to frequent fluctuations in population. Numbers build up quickly, then crash when food gets scarce. The myth of mass lemming suicides is based on sightings of large numbers of starving rodents wandering in search of food. They will swim across small bodies of water, but sometimes they hit water too wide for their strength and drown.

Lemming population peaks are flush times for arctic foxes, jaegers (predatory birds related to gulls), and snowy owls. Owls as a group have an effective–if brutal–way to take advantage of flush times by producing more young than usual. The robin nesting in your backyard typically lays a clutch of five or six eggs. She produces no more than one egg per day, and she doesn’t begin incubating until the last egg is laid. That means that all her young will hatch at approximately the same time.

Snowy owls lay their eggs about two days apart, and the female begins incubating as soon as the first egg is laid. A clutch may be as few as 4 eggs, although 5 to 7 is the usual range and at least one nest has been found with 13 eggs in it. The incubation period is about 33 days, so the oldest egg in a five-egg clutch will hatch ten days before the youngest.

The body heat from the oldest nestlings helps incubate the youngest eggs, but the difference in age means that the older chicks will be larger, louder, and more active than the younger birds. When the female brings food to the nest the older birds will attract more attention and usually get more food. In lean years the younger birds will get shut out altogether, and they will weaken and die. This grim process is helped along by a phenomenon called Cainism. When the young birds fade their older siblings kill and eat them. (I told you this was brutal.)

In the best lemming years, however, there is enough food around to raise a large brood, so all 5 or all 7 or all 13 of those eggs will survive to adulthood. Of course their problems are just beginning, because all these newly fledged lemming hunters are going out into the world at the moment when the lemming population has reached the crash phase of its boom-and-bust cycle. It is at times like these that we get an owl year.

We have records of owl years going back to the winter of 1876-’77. They have been happening roughly every five or six years since. We see some snowy owls every winter, but in owl years we see a lot more and we see them in places they don’t usually reach. There are even a few records of snowy owls in Louisiana in owl years.

Most years snowy owls are among the birds classed as partial migrants. Some birds go south for the winter, some stay put. The blue jays of northern Illinois are a local example of partial migration. In owl years a scarcity of food in the north combines with peak numbers of snowies, and lots and lots of birds come south.

In the old days a stuffed snowy owl was considered an excellent decoration for the parlor. Ornithologists traced the timing of owl years and learned where the owls were going in part by consulting taxidermists. A taxidermist could look at his records and find that 1876-’77 or 1892-’93 was when he got a lot of business stuffing snowy owls. In the winter of 1889-’90, a taxidermist in Mandan, North Dakota, stuffed no less than 500 snowies.