Text and Photo By Doug Backlund

Owls are special birds. Most species are secretive and nocturnal so the mere sighting of an owl is a special event in itself. But there are other special things about owls to consider. As a group, owls are highly specialized predators, with senses of hearing and sight so keen that we cannot begin to comprehend the life of an owl. With certainty, owls are the supreme predators of their preferred prey. Few predators are as efficient as owls but even so the availability of abundant prey is a driving force in the day to day life of owls. Starvation is one of main causes of mortality, especially for young owls.

One of my favorite owl species is the long-eared owl. This is a medium sized owl, smaller than the more common great horned owl, which the long-eared owl superficially resembles. Long-eared owls can be told from great horned owls by the smaller size and lack of a white throat. Also, the ear tufts of a long-eared owl are almost directly above the eyes while the great horned owl’s ear tufts are more to the side of the head. Among the owls that occur in South Dakota, the great horned owl is the largest and most powerful owl, all other owls avoid it. The long-eared owl is no exception. While great horned owls prey on anything they can kill, long-eared owls are more specialized. Great horned owls are perch hunters, waiting for prey to appear while remaining motionless on a favorite hunting perch. Long-eared owls are active search hunters, hunting while on the wing.

People who study owls face a difficult task. As Richard Manning wrote, "Owls are creatures that have conspired mightily through evolution to remain unseen." Cryptic and nocturnal, species like the long-eared owl truly fit that description. Diet, dates of nesting, general distributions and other basic information are fairly well established for some species but the relationships of owl populations to prey and habitat are poorly understood. Very little is known about population trends or movements of owls, including long-eared owls.

To understand long-eared owls, one must understand voles. Many vole species have cyclic population trends, ranging from extremely abundant to almost nonexistent in the same habitat patch over a period of several years. In South Dakota, there are two vole species that are found nearly statewide, one species that occurs only in the Black Hills, and another that occurs in the Black Hills and locally across the northern portions of the state. The most important species to the long-eared owl are the prairie vole and the meadow vole. Meadow voles are found in moist habitats with dense vegetation, therefore mostly restricted to lowlands, wetland edges, and riparian habitats. Prairie voles live in upland native prairies and grasslands statewide. Prairie voles are especially important, because this is the only vole species that can thrive in dry, upland grassland; thus this species can be abundant over huge landscapes of prairie habitat. This type of habitat once covered a vast area and supported millions of bison and pronghorn. These were nomadic species, constantly on the move in search of good forage. The bison, of course, are mostly gone; the movements of pronghorn are now constrained by fences and highways.

In the northern plains, long-eared owls are also nomadic creatures, following the cycles of the prairie vole and to a lesser extent the meadow vole. When vole populations are high, long-eared owls can be locally common but even then few people will see them. Long-eared owls depend on two components of habitat; extensive grasslands for the hunting of voles and dense thickets of trees or shrubs for roosting and nesting. Grasslands near woody draws or woodlands along streams and rivers are perfect habitat. Strictly nocturnal, hiding by day in dense thickets, the owls emerge from their hiding places after dark, coursing low and silent over grasslands in search of voles and other small mammals. Among the owls, their hearing and eyesight is unmatched. Long-eared owls are capable of hunting in near total darkness.

Nesting occurs in late April or early May. Like other owls, long-eared owls do not build their own nest, instead using the old nest of a crow or magpie, or some other available structure. The typical clutch is 4-6 eggs. Survival of the young owls is highly dependent on the availability of abundant prey. When prey is abundant it is not uncommon to find a high density of nesting long-eared owls in a small area. Up to four or five nesting pairs can be found in an area of less than a square mile. I have seen such nesting densities on several occasions in the Pierre area. In 1983, researchers working in Badlands National Park documented a high density of nesting long-eared owls, finding seven active nests, five of which were in an area of less than a square mile. High-density nesting indicates that the local vole population is high and the owls are taking advantage of the high vole population to maximize their reproductive efforts.

The owls often use communal roosts during the winter months. Roosts with as many as fifteen individuals have been found in the Pierre area. During the 1999 Pierre Christmas Bird Count we found a communal roost of eight long-eared owls. A total of ten long-eared owls were found on that count day, the highest ever recorded on the Pierre Christmas Bird Count. When the vole population drops, the owls move on. Even though the prime areas of roosting habitat in the count area were searched, no long-eared owls could be found during the 1998 or 2000 Pierre Christmas Bird Count.

Denver Holt is an owl researcher in Montana. He has established his own research institute devoted to the study of owls, the Owl Research Institute. Over the last fourteen years Denver and his associates have banded nearly 1000 long-eared owls. Years of intensive fieldwork have resulted in a number of recaptures of his banded owls and much valuable information has been gained. Denver’s research clearly shows that long-eared owls are nomadic, seeking grasslands with high densities of voles and raising their young in nearby dense thickets of cedars or willows. One of his banded long-eared owls was recovered near Mexico City, Mexico, over 2000 miles from where it was banded in Montana. He has found up to 80 long-eared owls on a single winter roost.

Records of band recoveries of long-eared owls from other studies show how widely these owls can wander. One owl banded in California in April was recovered in Ontario, Canada in October. Two banded in Minnesota and Saskatchewan turned up in Mexico. Three adults banded during a breeding season were recovered more than 280 miles away in the following breeding season.

In 1946, W. H. Over and C. S. Thoms published the Birds of South Dakota (Natural History Studies No.1. University of South Dakota Museum, Vermillion, S.D.) They described the status of the long-eared owl as common statewide. The most recent and best information available on the status of the long-eared owl comes from the S. D. Breeding Bird Atlas (Peterson, R.A. 1995. South Dakota Ornithologists’ Union, Aberdeen, S.D.). During the six-year project, the entire state was surveyed for breeding birds. One hundred twenty-four stratified, random blocks of 9 square miles each were designated across the state. In addition to the random blocks, 118 areas of special habitats and 173 blocks of various public lands were surveyed. All probable (2) and confirmed (3) nesting records of long-eared owls were in western South Dakota. There were seven possible breeding records in western South Dakota and only one possible nesting record was reported in eastern South Dakota, this in northern Marshall County. This data seems to indicate that long-eared owls are declining or gone from much of eastern South Dakota. If this is true, the decline in range may be related to the loss and degradation of grassland habitat needed to support large, cyclic populations of prairie voles and breeding populations of long-eared owls.

Long-eared owls are a beneficial species from a ranching perspective. Research has shown that when prairie vole populations are high, the rodents are capable of consuming much of the available vegetation in their habitat. Although small, voles make up for size in numbers, and can reach densities of 200 or more per acre under good conditions. Predation is one of the main controls on voles. Without the heavy predation of nomadic predators such as long-eared owls, voles theoretically could simply eat themselves out of existence. The nomads can respond to high vole populations quickly, in high numbers, unlike the more stable populations of resident, territorial predators. The closely related short-eared owl has a similar life history, a nomadic species that preys primarily on voles, except this owl species nests on the ground, thus the short-eared owl is not dependent on woodlands for nesting habitat while the long-eared owl is.

I hope there is always enough prairie left to provide hunting places for the nomadic owls. How much is needed, no one knows, but to maintain prairie voles and their predators in a functioning ecosystem for the long-term does require large tracts of prairie. Long-eared owls are beneficial to ranchers, but ranchers are even more beneficial to long-eared owls. By maintaining large tracts of grasslands for the grazing of livestock, ranchers provide most of the remaining habitat for prairie voles and long-eared owls. The Fort Pierre National Grasslands, Buffalo Gap National Grasslands, Grand River National Grasslands and Badlands National Park are also extremely important habitat. The trees and shrubs along streams and rivers and the woody draws of the western prairies are critical and must be protected to provide nesting habitat. The birds that build the nests that the long-eared owls use, the magpies and crows, are another link in the system. Even if one never sees them, remember that the long-eared owls are out there, searching for their next hunting and nesting area, just as they have done for eons.

"Lighten any check, mitigate the destruction ever so little, and the number of a species will almost instantly increase to almost any amount."