Wisconsin's 5 Resident Owls

Eastern-screech Owl Chicks, Megascops asio

Environmental Importance

Like all predators, owls play an important role in nature by removing from prey populations individuals that can be considered surplus. Most wildlife populations produce more offspring than their habitats can support. These surplus individuals eventually die of starvation, disease, or predation.

Owls can be a great benefit to places where rodent populations are high. Dense urban areas often suffer from an abundance of rats and mice spreading disease and burrowing into the soil.

For example, one owl can eat a large number of rodents and small mammals, with few animals preying on the owl in return. Because of this owls can be a great benefit to places where rodent populations are high. Dense urban areas often suffer from an abundance of rats and mice spreading disease, and rural agricultural communities have their crops consumed and soil eroded from burrowing voles and field mice. Without owls, and other top predators, rodent populations could explode and exacerbate the effects they produce.

What Makes Owls Great Hunters?

Owls have special tools that give them an edge over their prey. They have incredibly sensitive vision and hearing, silenced feathers, piercing talons, and super sharp beaks. Additionally, their heads can rotate up to 270 degrees. This allows them to place their eyes and ears in specific positions to better locate other animals. Some owls have tufts of feathers that stand atop their head were one might expect ears to be, but they are not ears at all. Unlike external protruding human ears, the hearing structures of a bird are internal. The earholes of owls that primarily hunt in the dark are asymmetrical, meaning they are offset from one another, one being higher or lower than the other. This ear positioning, and the satellite shaped feather configuration of an owl’s face, allows them to triangulate the sounds of prey in darkness or cover.

Owls are also equipped with very special feathers that silences their flight. You may not imagine that bird feathers are all that noisey to begin with, but when compared with other birds of prey, like the falcons or hawks, owls are almost completely silent in flight. It is strange to see something so large glide so quietly through thick wooded swamps, without the slightest whisper of wind, or ruffle of leaf.

Barn Owl, Tyto alba

Barn Owl, Tyto alba

Habitat

Barn Owls live in open habitats that include grasslands, marshes, agricultural fields, strips of forest, woodlots, ranchlands, brushy fields, and suburbs and cities. They nest in tree cavities, caves, and in buildings

Diet

Barn Owls eat mostly small mammals, particularly rats, mice, voles, lemmings, and other rodents; also shrews, bats, and rabbits. Most of the prey they eat are active at night, so squirrels and chipmunks are relatively safe from Barn Owls. They occasionally eat birds such as starlings, blackbirds, and meadowlarks. Nesting Barn Owls sometimes store dozens of prey items at the nest site while they are incubating to feed the young once they hatch.

Nesting

Nesting Facts
Clutch Size 2-18 eggs
Broods 1-3 broods
Incubation 29-34 days
Nesting 50-55 days
Eggs Dull white

Barn Owls put their nests in holes in trees, cliff ledges and crevices, caves, burrows in river banks, and in many kinds of human structures, including barn lofts, church steeples, houses, nest boxes, haystacks, and even drive-in movie screens.

Behavior

Barn Owls fly slowly over open fields at night or dusk with slow wingbeats and a looping, buoyant flight. They use their impressive hearing, aided by their satellite-dish-shaped faces, to locate mice and other rodents in the grass, often in complete darkness. Barn Owls are usually monogamous and mate for life, although there are some reports of males with more than one mate. Males attract their mates with several kinds of display flights, including a “moth flight” where he hovers in front of a female for several seconds, his feet dangling. He also displays potential nest sites by calling and flying in and out of the nest. After the pair forms, the male brings prey to the female (often more than she can consume), beginning about a month before she starts laying eggs. Barn Owls defend the area around their nests, but don’t defend their hunting sites; more than one pair may hunt on he same fields

Barred Owl, Strix varia

Barred Owl, Strix varia

Habitat

Barred Owls live year-round in mixed forests of large trees, often near water. They tend to occur in large, unfragmented blocks of mature forest, possibly because old woodlands support a higher diversity of prey and are more likely to have large cavities suitable for nesting. Their preferred habitats range from swamps to stream sides to uplands, and may contain hemlock, maple, oak, hickory, beech, aspen, white spruce, quaking aspen, balsam poplar, Douglas-fir, lodge pole pine, or western larch.

Diet

Barred Owls eat many kinds of small animals, including squirrels, chipmunks, mice, voles, rabbits, birds (up to the size of grouse), amphibians, reptiles, and invertebrates. They hunt by sitting and waiting on an elevated perch, while scanning all around for prey with their sharp eyes and ears. They may perch over water and drop down to catch fish, or even wade in shallow water in pursuit of fish and crayfish. Though they do most of their hunting right after sunset and during the night, sometimes they feed during the day. Barred Owls may temporarily store their prey in a nest, in the crook of a branch, or at the top of a snag. They swallow small prey whole and large prey in pieces, eating the head first and then the body.

Nesting

Nesting Facts
Clutch Size 1-5 eggs
Broods 1 broods
Incubation 28-33 days
Nesting 28-35 days
Eggs Pure white

Barred Owls usually nest in a natural cavity, 20–40 feet high in a large tree. They may also use stick platform nests built by other animals (including hawks, crows, ravens, and squirrels), as well as human-made nest boxes. Barred Owls may prospect a nest site as early as a year before using it. No one knows whether the male or the female chooses the site.

Behavior

Barred Owls roost on branches and in tree cavities during the day and hunt by night. Territorial all year round, they chase away intruders while hooting loudly. They are even more aggressive during nesting season (particularly the females), sometimes striking intruders with their feet. Pairs probably mate for life, raising one brood each year. Their nests are preyed upon by other large owls and hawks, as well as by weasels and raccoons. When humans interfere with a nest, the parent may flee, perform a noisy distraction display with quivering wings, or even attack. Other birds recognize Barred Owls as predators; small songbirds, crows, and woodpeckers may band together to mob them. Their most dangerous predator is the Great Horned Owl, which eats eggs, young birds, and occasionally adults.

Eastern-screech Owl, Megascops asio

Eastern-screech Owl, Megascops asio

Habitat

Almost any habitat with sufficient tree cover will do for this cosmopolitan owl. Tree cavities or nest boxes are essential, and fairly open understories are preferred, but Eastern Screech-Owls live and breed successfully in farmland, suburban landscapes, and city parks. Screech-owls cannot survive if all trees are removed, but the species readily recolonizes once trees are replanted, especially if nest boxes are also provided.

Diet

Eastern Screech-Owls eat most kinds of small animals, including birds and mammals as well as surprisingly large numbers of earthworms, insects, crayfish, tadpoles, frogs, and lizards. They eat many kinds of mammals, including rats, mice, squirrels, moles, and rabbits. Small birds taken as prey include flycatchers, swallows, thrushes, waxwings, and finches, as well as larger species such as jays, grouse, doves, shorebirds, and woodpeckers. This owl is agile enough to occasionally prey on bats, and can rarely even be cannibalistic. When prey is plentiful, Eastern Screech-Owls cache extra food in tree holes for as long as four days.

Nesting

Nesting Facts
Clutch Size 2-6 eggs
Broods 1 brood
Incubation 27-34 days
Nesting 26-30 days
Eggs White

Eastern Screech-Owls nest in holes and cavities, but never dig a cavity themselves. Thus, they depend on tree holes opened or enlarged by woodpeckers, fungus, rot, or squirrels. They often occupy abandoned woodpecker nest holes. Eastern Screech-Owls readily accept nest boxes, including those built for Wood Ducks or Purple Martins, and sometimes nest in wood piles, mailboxes, or crates left on the ground.

Behavior

Eastern Screech-Owls are chiefly active at night, though they often hunt at dawn or dusk, and occasionally in daylight. These versatile hunters sit and wait in the trees for prey to pass below. They tend to pounce from perches six to ten feet off the ground, occasionally snatching an insect or bat on the wing or hitting shallow water talons-first to snag fish or tadpoles. Most flights are short (less than 75 feet or so). When traveling between perches, these owls often drop, fly straight, then rise again, in a characteristic U-shaped pattern. Eastern Screech-Owls form stable matches, usually one male with one female but occasionally one male with two females. Males defend small territories containing several cavity roost spots. When nesting, the female stays in the nest hole except for brief dawn and dusk excursions. She and the nestlings are fed by her mate, though it is the female who tears the prey into small bits for the babies. At fledging, the young first hop to the ground or nearby branches, using feet and fluttering wings to climb laboriously back to safety. Young gain flight and hunting skills slowly; they depend on their parents for food for 8–10 weeks after fledging. Both parents feed the youngsters at this stage, and adults, especially the females, shelter together with the young in communal tree roosts. Gradually, as the young gain skill, they begin to roost and hunt apart from their parents and siblings.

Great Horned Owl, Bubo virginianus

Great Horned Owl, Bubo virginianus

Habitat

Great Horned Owls usually gravitate toward secondary-growth woodlands, swamps, orchards, and agricultural areas, but they are found in a wide variety of deciduous, coniferous or mixed forests. heir home range usually includes some open habitat — such as fields, wetlands, pastures, or croplands — as well as forest. In deserts, they may use cliffs or juniper for nesting. Great Horned Owls are also fairly common in wooded parks, suburban area, and even cities.

Diet

Great Horned Owls' prey range in size from tiny rodents and scorpions to hares, skunks, geese, and raptors. They eat mostly mammals and birds — especially rabbits, hares, mice, and American Coots, but also many other species including voles, moles, shrews, rats, gophers, chipmunks, squirrels, woodchucks, marmots, prairie dogs, bats, skunks, house cats, porcupines, ducks, loons, mergansers, grebes, rails, owls, hawks, crows, ravens, doves, and starlings. They supplement their diet with reptiles, insects, fish, invertebrates, and sometimes carrion. Although they are usually nocturnal hunters, Great Horned Owls sometimes hunt in broad daylight. After spotting their prey from a perch, they pursue it on the wing over woodland edges, meadows, wetlands, open water, or other habitats. They may walk along the ground to stalk small prey around bushes or other obstacles.

Nesting

Nesting Facts
Clutch Size 1-4 eggs
Broods 1 brood
Incubation 30-37 days
Nesting 42 days
Eggs Dull white

Great Horned Owls typically nest in trees such as cottonwood, juniper, beech, pine, and others. They usually adopt a nest that was built by another species, but they also use cavities in live trees, dead snags, deserted buildings, cliff ledges, and human-made platforms. They occasionally nest on the ground. Pairs may roost together near the future nest site for several months before laying eggs.

Behavior

Great Horned Owls roost in trees, snags, thick brush, cavities, ledges, and human-made structures. They are active mostly during the night — especially at dusk and before dawn. When food supplies are low they may begin hunting in the evening and continue into the early morning. In winter they may hunt during daylight hours. Mated pairs are monogamous and defend their territories with vigorous hooting, especially in the winter before egg-laying and in the fall when their young leave the area. Great Horned Owls respond to intruders and other threats with bill-clapping, hisses, screams, and guttural noises, eventually spreading their wings and striking with their feet if the threat escalates. They may kill other members of their own species. Crows, ravens, songbirds, and raptors often harass Great Horned Owls with loud, incessant calls and by dive-bombing, chasing, and even pecking them. Unattended eggs and nestlings may fall prey to foxes, coyotes, raccoons, lynx, raptors, crows, and ravens. Both members of a pair may stay within the territory outside of the breeding season, but they roost separately.

Long-eared Owl, Asio otus

Long-eared Owl, Asio otus

Habitat

Long-eared Owls roost in dense vegetation and forage in open grasslands or shrublands; also open coniferous or deciduous woodlands. In Wisconsin Long-eared owl nests are found in coniferous or deciduous forests near open meadows.

Diet

Long-eared Owls eat mostly small mammals, including voles, many kinds of mice, shrews, pocket gophers, and young rats or rabbits. They hunt over open ground or below the canopy in sparsely forested areas. Prey items usually weigh up to about 3.5 ounces, often less than 2 ounces. They also sometimes eat small birds, capturing them on the ground or (in the case of roosting birds) from low vegetation. Rarely, Long-eared Owls eat moles, bats, weasels, chipmunks, ground and tree squirrels, snakes, and lizards.

Nesting

Nesting Facts
Clutch Size 2-10 eggs
Incubation 25-30 days
Eggs White

Long-eared Owls typically use stick nests abandoned by other bird species. Less often, they raise their young in cavities in trees or cliffs, in abandoned squirrel nests, or on the ground. Long-eared Owls in Oregon nest have made nests of dwarf mistletoe “brooms”—dense branch profusions that form in response to the mistletoe infection.

Behavior

Long-eared Owls hunt on the wing, coursing back and forth low above open ground. They may also hover over prey, or hunt from perches in strong winds. They kill small mammals with a bite to the back of the skull, and often swallow their prey whole. Nesting Long-eared Owls sometimes form loose colonies, occupying nests as close as 50 feet apart. They may also share nesting areas with American Crows. Outside of breeding season, the owls roost in groups of up to 100 birds. Older nestlings are called “branchers” because they leave the nest to take up residence in surrounding trees. They move around by jumping, hopping, and pulling themselves up with wings and bill. Long-eared owls usually form monogamous pairs. Bonding probably begins in winter, before communal roosts disband. Courting males make a complex series of calls and perform an aerial, zig-zagging display over suitable nesting habitat, with glides and wingbeats interspersed with wing-claps.

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