Winter 1998

[TEXT ARCHIVE WEB-PUBLISHED AUGUST 2001.
ORIGINAL PRINT PUBLICATION DATE: WINTER 1998.]

Short-eared owl: Winter Grassland Hunter
By Sheryl De Vore

As the sun paints its last pink rays against a cold winter sky, two humans wait, atop a hill overlooking fields and marshes in DuPage County, for the giant moths. Suddenly, a nasal, high-pitched barking signals their arrival. Three short-eared owls (Asio flammeus) have come to hunt for dinner. An owl skims the field, slightly drooping its 20-inch wings and displaying its characteristic buff-white wing patches and dark crescent in the underwing. Like a giant silent moth, the owl snatches its prey: a vole.

In winter, the short-eared owl visits the Chicago Wilderness region to find food. This bird has a large, round head, stout neck and piercing yellow eyes contrasting with dark facial disks. Its visible 'ears' are actually hair tufts used to warn encroaching males or attract females. As in many owl species, the ears are hidden slits at the sides of the head, situated asymmetrically to help the short-eared zero in on its prey.

Unlike the great horned owl, which is faring well despite man-made changes in the landscape, the short-eared suffers from diminishing habitat. The wet prairie nesting habitat of this state-endangered bird is declining, and the short-eared owl is no longer a common breeding bird in the northeastern United States. Breeding locations are confined mostly to Alaska and northern Canada, south through the southern half of the U.S.

The female needs tall grasses or reeds in which to build and lay her four to eight round white eggs. She typically incubates for 21 days; the young fly 31 to 36 days later. Confirmed nestings of short-eared owls in Illinois in recent decades are rare. A pair at Goose Lake Prairie (Grundy County) in 1973 produced two young. In 1978, the short-eared owl was placed on the Illinois Endangered Species list, where it remains today. By 1996, the only reported short-eared owls nesting in the state were in Vermilion County.

The best chance to find a short-eared owl in the Chicago Wilderness region is in winter. An irruptive species, the short-eared owl goes where the food is. A declining vole population north may bring the short-eareds south. If several of them can find a nice-sized field or marsh containing a good supply of prey, they may remain at the site through winter to feed.

In 1995, birders observed 11 short-eared owls hunting at the Glenview Naval Air Station from late December through February, but only a few owls returned in the winter of 1996, and planned development of that site may mean the owls will no longer find the place suitable for hunting. Recently, however, a group of concerned citizens have joined together to save some of this species' habitat. In December, the Glenview Village Board voted to preserve the 14-acre high-quality prairie on the grounds of the former naval air station where the owls have been seen.

Several short-eared owls have also been seen at Glacial Park in McHenry County in recent winters. At Springbrook Prairie Forest Preserve in DuPage County, eight were seen in December 1996.

To learn if short-eared owls and other species are in the region, you can call the Chicago rare bird alert for a recorded message. The number is (847) 265-2118. To observe short-eared owls, station yourself near their hunting grounds one-half hour before the sun sets. Sit quietly and patiently, making no quick movements. Remember to dress appropriately for cold weather.

Your first sighting might be of a northern harrier, sometimes called a marsh hawk, which shares feeding grounds and roosting sites with short-eared owls. Both species hunt the marshy fields, but harriers fly by day, while owls appear at dusk. When the two species meet, the owl sometimes gives its raspy dog-like call, typically reserved for the breeding season, telling the harriers it is time for the changing of the guard.