Sunday, January 29, 2017

Great gray owls are magnificent birds

A great gray owl scrutinizes a visitor to a Minnesota bog

January 29, 2017

NATURE
Jim McCormac

Milton B. Trautman was the undisputed dean of Ohio birds. Trautman, who died in 1991 at the age of 91, hailed from the shotgun era of ornithology. In his early days, a significant bird record hardly counted if it wasn't collected.

Imagine, then, Trautman's surprise on Oct. 30, 1947. He was boating to his home on South Bass Island in Lake Erie when he spotted a huge bird perched in a scrubby tree on tiny Starve Island. Drawing nearer, Trautman realized it was a great gray owl - dimensionally, the largest North American owl.

Trautman must have been bouncing off the gunwales, especially when he realized the rocky surf made getting in range to shoot the bird impossible.

Although he didn't make a museum specimen of the bird, he carefully described one of Ohio's few records of this northern owl.

A great gray owl is a mind-numbing bird. It measures over 2 feet in length, with a wingspan stretching nearly 4 1/2 feet. Despite its massive size, the owl weighs less than 2 1/2 pounds - nearly a pound lighter than the much more familiar great horned owl. Dense insulating feathers, which keep the great gray owl warm on frosty boreal nights, make up much of its mass.

I recently made a foray into northern Minnesota bog country, where great grays routinely can be found. At times, I wished I had this species' feathers - the temperatures were well below zero every day, and they sank to minus 29 one frigid morning.

Great gray owls do much of their hunting at dawn and dusk, and cruising appropriate habitat can yield sightings. One magical evening, we came across a knot of birders who had found an owl perched in a nearby snag. The bird was intent on hunting, its head on a swivel as it listened for rodents.

Owls have long fascinated people, and it's no wonder when one looks into the visage of a great gray owl. Piercing yellow eyes are fixed in a large humanlike facial disk, and when the bird deigns to bayonet you with those eyes, the effect is startling. I would not wish to be the luckless vole on the receiving end of that stare.

As the north woods are typically blanketed with thick snow cover in winter, the owls do much of their hunting by ear. Voles and other small rodents mostly remain in tunnel-like runways under the snow - seemingly out of sight and out of mind.

There's no escaping the owls, though. A hunting great gray constantly scans the snow surface, using its incredible hearing to locate rodents under the snow. Offset ears allow it to triangulate on sounds, pinpointing the victim from amazing distances.

When a vole is located, the owl silently swoops to the spot, dives through the snow blanket, and seizes the hapless animal sight unseen.

Although it has been 70 years since Trautman's Ohio sighting of a great gray owl, it's possible that another could appear here. Somewhere along Lake Erie would be most likely. Whoever finds it would be in owl heaven.

Naturalist Jim McCormac writes a column for The Dispatch on the first, third and fifth Sundays of the month. Find out more about the birds he saw in Minnesota bog country at www.jimmccormac.blogspot.com.

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