The Prairie Owl
For starters, they probably should have been named "prairie owls" rather than short-eared owls. That's because owls don't have external ears; short, long or otherwise. The features loosely referred to as ears are really tufts of feathers on the top of the head and have nothing to do with hearing. Further confusion arises from the fact that these ear-like tufts are so small and inconspicuous that they're not usually observed.
Other owls hunt at night, but short-ears hunt during the day. Owls lurk secretly in the forest, but short-ears prefer open prairies and marshes. Most owls nest in trees, but short-ears nest on the ground. Because of their diurnal habits and penchant for wide open spaces, they're more easily observed than their woodland dwelling cousins. They're also interesting and fun to watch.
Other aliases for the short-eared owl are bog owl, grass owl, meadow owl, swamp owl or even mouse owl. All of these colloquial names derive from the habitats the owls inhabit or the food they prefer, not from our misguided sense of bird anatomy.
Short-eared owls are found in North America, Europe and Asia, as well as in certain areas of South America. They truly are denizens of the prairie because they shun the forest in favor of the openness of vast acreages of high quality grass. They nest, hunt and roost in hay meadows and pastures.
In Missouri they are most often observed in winter, but they have nested sporadically in northern and southwestern counties. Most of our short-ears probably breed in the prairie states north and west of Missouri, and in Canada's prairie provinces.
Well known owls of Missouri, such as great horned, barred and screech, typically inhabit mostly forested areas. Less common but more closely related to the short-ear is the long-eared owl, which also prefers forests, typically coniferous stands. As the name implies, their ear tufts are more conspicuous.
Relatively little is known about the short-eared owl's breeding biology in Missouri due to the small number of nest records, but biologists speculate that more nesting occurs during years of high prey numbers. They also believe the Cropland Reserve Program (CRP) greatly improved potential for breeding in our state. Land enrolled in CRP was taken out of intensive farming practices for 10 years in favor of uses that reduced erosion and provided greater wildlife food and cover. This land provides a good winter home for both short-ears and northern harriers, as well as bobwhites, turkeys and lots of other species.
Female short-eared owls build nests under a canopy of grass. They typically lay from four to 14 eggs, with an average of five to seven, over a period of about four weeks. Because incubation lasts about four weeks, the last egg laid will hatch three to four weeks later than the first. When food is scarce and hunting is poor, only the more robust, larger young may feed, and those that hatched later will starve or be eaten by their more mature siblings. Young are able to fly about four weeks after hatching.
In late autumn, birders trek to their favorite prairie meadows or pastures to see if the short-ears have returned to roost and hunt for the winter. Like most birds, short-ears are highly mobile and will seek regions with abundant food supplies.
Researchers gather information about the short-eared owl's feeding habits from regurgitated pellets found at winter roosts. They can identify prey species by closely examining undigested skulls and other bones. Voles (small, stocky short-tailed rodents) account for more than 90 percent of the short-eared owl's diet in some studies.
Vole population levels fluctuate over about a 4-year cycle, and high numbers of them can result in economic damage to small trees and crops. The appearance of a group of short-eared owls in the pasture should be welcomed as nature's way of keeping the vole population in check.
In excellent habitat with high prey populations, some winter roosts can contain up to 200 short-ears, but Missouri roosts are much smaller.
Suppertime for the owls begins in late afternoon as they take wing from their daytime roost in a dense, grassy swale. During times of deep snow, they will roost in trees. Once in the late 1970's, I found them roosting in a row of eastern red cedars for a few days until the snow began to melt.
On long wings, short-ears glide casually back and forth above their hunting grounds, watching and listening for a sign of a vole in the grassy expanse below. In an instant, an owl will turn abruptly, wheel and fold its wings and stoop on its prey. If successful, an owl remains on the ground, quickly killing and devouring its catch. It always swallows it whole and head first.
Northern harriers, formerly known as marsh hawks share the winter hunting grounds with short-eared owls and are equally skilled at hunting. These two birds of prey compete directly for territory and food. Harriers will frequently harass short-ears, forcing the owls to drop the prey they catch.
The flight of short-ears appears buoyant and effortless due in large part to their long and graceful wings. With a wingspan of up to three and one half feet and a weight of a mere one-half to one pound, short-eared owls have what ornithologists call favorable "wing loading." This means lots of wing surface giving lift to a relatively small body, allowing the owls to fly and hunt for long periods at a time while using relatively little energy.Thanks to specially modified feathers, owls are capable of silent flight. The leading edges of flight feathers have an irregular or jagged edge which decreases turbulence and muffles the sound of air rushing over the wings during flight. This is no doubt an adaptation for greater stealthiness in hunting for prey since the owl relies heavily on hearing for locating and accurately striking at prey.
Unlike the ears of most animals, which are directly opposite from each other, an owl's ears, which are not related to the feathered tufts, are offset, or at different elevations on the head. This allows owls to hear a greater range of frequencies in three-dimensional sound, allowing them to isolate and locate the origin of sounds quickly.
Although short-ears typically hunt from the wing, I observed one hunting from a low perch two years ago while I was shooting photos for this article. I spent many evenings watching a small group of winter resident owls in a large CRP pasture in northern Callaway County.
In the dim light of the setting sun, a lone owl swooped low over the pasture and landed on a leaning weathered fence post a mere 20 feet away. I cautiously panned my camera in the direction of the owl. When I found focus, I felt more like the subject than the photographer. The owl's blazing yellow eyes glared down the barrel of my lens and into my storehouse of memories. He soon became distracted by something in the thick grass halfway between us. He stretched his neck and glared downward, then turned his head from side to side, using all of his senses.
After a couple minutes he pounced. As I pulled back from my camera eyepiece to see what was happening just a few feet away, I saw the owl flailing away at the turf with his lethal talons. Dead grass flew into the air. When the owl stopped, I could see a vole in its grasp.
The owl launched skyward, carrying about as much grass as vole. I hoped he'd land nearby and give me a chance for some rare predator-with-prey photos, but he slipped over the horizon and into the dusk. I got no photographs, but what a rich memory.