Monday, April 16, 2012

Eastern Screech-Owl


The Eastern screech owl is a master of camouflage. Its ear tufts aren’t really ears; they just help the bird blend into backgrounds.

NATURE
Eastern screech owl common but rarely spotted
The Columbus Dispatch
April 15, 2012

Somewhere not far from you sits Ohio’s most common avian predator. But chances are that most readers have never seen one.

You might have heard its calls: eerie descending whistles, perhaps reminiscent of a baby banshee wailing through a muffler; or its other song, a strange, quavering monotone trill. Either call will draw one’s ear, but good luck seeing the singer.

Eastern screech owls are masters of camouflage. The small owls — less than 9 inches long and weighing little more than a smartphone — are strictly nocturnal. During the day, a roosting screech owl typically holes up in a tree cavity or nest box. Sometimes they’ll sit tight against a tree trunk, and their plumage matches the tree’s bark to a remarkable degree. The owl’s prominent ear tufts further the illusion that the bird is a broken-off snag.

Come nightfall, the owls go on the hunt. Specialized adaptations allow screech owls to efficiently track down and dispatch prey. Supersized ears — not those tufts, which are only for camouflage — detect the faintest sounds. The ears, which are hidden under the feathers on the sides of the head, are slightly offset, which allow the owl’s brain to better triangulate on the sound’s location.

Proportionately enormous eyes contain many more rods and cones than yours do, and these uber-peepers allow the owl to see through the night’s gloom.

The prey will never know what hit it. Ruffled leading edges on the flight feathers make for a silent, deadly flight. Once seized, the victim has no chance of escape, as the owl’s talons lock into place like a vise. A strong bite to the vertebrae finishes off the meal to be. After the owl wolfs down its kill, the indigestible parts will be unceremoniously cast out later as a pellet of fur and bones.

Few birds are as adaptive as screech owls, and they can be surprisingly common in urban landscapes. A 1981 survey of a 15-mile-diameter circle in Toledo found 112 owls, and I’m sure it missed some. Their frequency in Columbus is probably similar.

Screech owls tolerate a wide variety of habitats and have an incredibly varied diet. I have found them in heavily developed neighborhoods, remote forests and patchy woodlots in farm country. They’ll also eat almost anything: mice, songbirds, snakes, insects. If it’s small and tasty, it’s fair game. Screech owls snag fish and crayfish, too.

Even a crude whistled imitation of a screech owl call can bring in a bird to investigate. Try it if you think one is around. The tufted night stalkers are inquisitive and will usually fly right in if within earshot. If your mimicking finds its mark, the owl will call back, often from close range.

If you get the chance to view a screech owl, note its color. The species is unique among Ohio’s owls in that it comes in two color forms: red and gray. The gray morphs seem to predominate throughout Ohio; reds are more common in the south than the north.

Screech owls will use nest boxes to roost and to nest. If you have owls in the neighborhood, placing a box might lure some tufted tenants. Plans for building a box and other screech owl info, including recordings, can be found at the Ohio Division of Wildlife’s website, http://www.wildohio.com/.

Naturalist Jim McCormac writes a column for The Dispatch on the first and third Sundays of the month. He also writes about nature at www.jimmccormac.blogspot. com.

Further afield

You won’t want to miss this: Dawes Arboretum botanist David Brandenburg will present a talk titled “Should I Have Eaten That? Allergies, Blisters, Convulsions, Delusions and Other Adventures With Poisonous Plants” at 7:30 p.m. April 24 at the Grange Insurance Audubon Center, 505 W. Whittier St. The talk is sponsored by Columbus Audubon.

StumbleUpon.com

4 comments:

KaHolly said...

Great information about the Screech Owl! Thank you.

Rick said...

Is that one of the boardwalk owls?

Jim McCormac said...

Glad you liked the post, KaHolly! That's a beautiful Bruce Miller shot of the owl, Rick, and yes it is one of the famed Magee boardwalk owls.

Trendle Ellwood said...

I enjoyed reading this and learning more about this lovely little owl. So interesting about the ear tufts. The photograph by Bruce Miller is awesome too!