Common Barn-owl (Tyto alba)

Legal status in U.S.: not endangered Legal status in WI: endangered 1997 numbers in WI: unknown Length: 13-15 inches Wingspan: 41-45 inches Weight: female 17-25 ounces male 14-19

Description

What graceful, ghostly bird can locate a mouse by sound and catch it in the dark of night? The common barn-owl, one of Wisconsin's best natural mousetraps.

Barn-owls are sometimes called "monkey-faced owls" because of their white, heart-shaped faces and dark eyes. These crow-sized owls are distinguished from other Wisconsin owls by a pale face, long legs, light underparts and a rusty back speckled with black. Barn-owls and other owls are classified in the same bird order (Strigiformes), but barn-owls are in their own family (Tytonidae) because their skeletal structure and pale, stiff facial feathers differ from those of typical owls (Strigidae).

Please click button for a comparison of
a Barn Owl and a Great Horned Owl.

Barn-owls don't have ear tufts like great horned owls or screech owls. But this doesn't mean barn owls don't have ears. Ear tufts are just feathers; the owl's real ears are behind its round facial disks, which help direct sound into the ears. Barn owls' ears also are asymmetrical; they are different sizes and one is located higher on the head than the other. This enables the bird to sense direction and distance by differences in the intensity of the sound that reaches each ear. Barn owls use their ears to locate food. They are very accurate hunters, even in the pitch black. Barn owls also have special feathers on the front edges of their wings that reduce the amount of noise they make when flying. Their quiet flight prevents prey from hearing them approach.

Please click button for a close-up
of a Barn Owl's inner-ear opening.

Hearing a barn-owl's voice is unforgettable: "A shriek broke the stillness of the black night, a ghostly shadow passed by and my skin crawled." Not an overly flattering description of a barn-owl vocalization! Barn-owls' high-pitched screeches or hiss-screams are memorable, but the birds are not harmful. They make these sounds to warn their young of danger, to announce their arrival at the nest and to proclaim their territory.

Food

Why are barn-owls called one of Wisconsin's best natural mousetraps? Because they eat 1.5 times their weight in food, mostly mice and meadow voles each day. That's like a 100-pound person eating 150 pounds of food every day! A barn-owl family of two adults and six young may eat as many as 1,000 rodents during the nesting period. Although barn-owls eat mostly mice and meadow voles, they also consume shrews, rats and, when other food is scarce, small birds. They occasionally eat insects, amphibians and reptiles.

Nighttime is when barn-owls hunt. Their excellent hearing helps them capture prey, which they usually swallow whole. They are unable to digest the fur, feathers or bones of the animals they eat, and cough up the undigested parts in a dark, odorless lump called an owl pellet. We can find out what an owl has eaten by examining the remains in the pellet.

Breeding Biology

When they are one year old, barn-owls can breed. The male courts the female by chasing her, bringing her mice and uttering a series of rapid squeaking noises. A pair may use the same nesting site each year. Barn-owls select well protected nesting sites, usually in tree cavities, abandoned buildings, church steeples, silos or the location that gave them their name. . .barns. Before settlement, barn-owls nested in tree cavities and on cliff ledges.

Barn-owls can breed year-round. In Wisconsin they usually rear a brood of young in the spring and, if food is plentiful, may rear a second brood in the late summer or early fall. Eggs are laid on a bare surface or, if the nest was used the previous year, on a thick mat of flattened pellets. The female lays an egg every two days until 5-7 white eggs are in the nest. When the first egg is laid, she begins incubating. Thus, when the first egg hatches about 30 days later, that owlet is older than the next one to hatch. It often is stronger and more able to take food from the parents.

Both adults hunt food for their snow-white, downy young. They bring prey to the nest, where the owlets swallow it whole. Sometimes the younger nestlings don't get enough food and die. The older, stronger owlets may even eat the weaker ones. Great horned owls and raccoons also eat young barn-owls. The young owls fledge when 8-10 weeks old.

Barn-owls have difficulty surviving severe winter weather. Their bodies store little fat, so the birds have minimal extra energy to draw on when deep snow hides the small mammals they eat. If they don't find a constant supply of food, especially during cold spells when they use a lot of energy to keep warm, they may die. On average, barn-owls live 3-4 years.

Distribution

If you traveled to Europe or Africa, South America or Southeast Asia, Australia or North America, you could see barn-owls. They live in temperate and tropical regions nearly worldwide.

In Wisconsin, barn-owls generally live only in the southern third of the state. Since severe winter weather limits where they can survive, southern Wisconsin forms the northern edge of their North American range.

Barn-owls hunt along uncultivated field edges, fence rows and wetland edges, where their prey is most available. They nest and roost in dark, secluded places. During the winter, some adults wander locally while others migrate southward. Young owls generally move south the winter after they fledge and may return the following spring.

A map outlining Pre-1977 and 1997 to Present Distribution is also available.

History in Wisconsin

Although Wisconsin's barn-owl population was never high, a decrease in sightings since the 1950s suggests that it has been declining. No one factor has been clearly defined as the major cause for this decline. There appear to be several contributing factors:

• Some modern agricultural practices have reduced barn-owl habitat. For example, shifts from cover crops such as oats and hay to row crops like corn remove food and shelter for mice and voles, barn-owls' primary prey. Development of land, removal of hedgerows and draining of wetlands also have destroyed much barn-owl habitat.
• Fewer nesting sites may be limiting the barn-owl population in Wisconsin. Modern metal farm buildings have few entry windows, which prevents them from being used by nesting barn owls. Woodlot management which removes large dead trees that have good nest cavities also reduces the number of possible nesting places.
• Even though barn-owls help farmers by eating large numbers of grain-consuming mice, they have been blamed for poultry losses. As a result, they are sometimes unjustly and illegally shot or poisoned.

Current Status

Barn-owls were placed on the Wisconsin Endangered Species List in 1979. At present, the status of the barn-owl population in Wisconsin is unknown. The last reported nesting occurred in 1985, when a pair occupied a large silver maple in Deerfield (eastern Dane County).

Research and Management

When research showed that the number of barn-owls in Wisconsin was declining, the DNR recommended that barn-owls be listed as a state endangered species and that action be taken to increase the barn-owl population in the state. Since 1981, the Milwaukee County Zoo has bred barn-owls in captivity and the DNR has released them in southeastern Wisconsin. To date, 79 birds have been released, but it is not known if any have nested in Wisconsin. Researchers and volunteers are also building and installing nestboxes in suitable barn-owl habitat. These nestboxes have been successful in Ohio and New Jersey, and hope is high that the boxes will be used by barn-owls in Wisconsin.

In 1985, DNR biologists began attaching radio transmitters to some of the owls it released. The transmitters broadcast a signal to receivers that allow researchers to locate an owl's daytime roost and monitor nocturnal movements. These and future studies will help provide needed information about how far barn-owls go to hunt, what kind of habitat they use and where they go after the nesting season.

What You Can Do

Wisconsin citizens can help restore barn-owls by volunteering time and by contributing to the DNR's Endangered Resources Fund on their state income tax forms. Contributions will help the DNR and volunteers build and install barn-owl nest boxes and will be used to purchase radio equipment for tracking barn-owls. Also, please help researchers by reporting any sightings of barn-owls to the Bureau of Endangered Resources.

Barn-Owl Nest Box Plans

Further Reading

Bunn, D.S., A.B. Warburton and R.D.S. Wilson. 1982.
The Barn-owl.
Buteo Books, Vermillion, SD. 264 pp.

Excerpt from THE ENDANGERED AND THREATENED VERTEBRATE SPECIES OF WISCONSIN

Status: State Endangered (1979).

Occurrence: Rare summer and winter resident south and central. Found in small numbers north to Polk, Clark, Vilas and Marinette counties, which is the edge of their northern range in Wisconsin. A map outlining Pre-1977 and 1997 to Present Distribution is available.

Aid to ID: Plumage is whitish or pale cinnamon below, sometimes speckled with black, and rusty buff or orange buff above with dark gray and white spots or speckled black. Whitish, heart-shaped facial disk is distinctive, although females have darker faces and larger spots on breast and belly. Barn owls lack ear tufts. Eyes are relatively small and dark. Females are larger, heavier, and more speckled than males.

Habitat: Grass habitats, including wet meadows, lightly grazed pastures, hayfields and abandoned agriculture fields. Common nesting sites include silver maple, American sycamore, and white oak. Human-made cavities include sites in barn silos, church steeples, warehouses, and grain elevators.

Food Habits: Meadow vole (Microtus pennsylvanicus) is most important prey animal. Short-tailed shrew (Blarina brevicauda) is important as secondary prey.

Natural History:

Breeding: Breed at 1 year. Clutch size: usually 5-6 pure white eggs; laid from March to July. Incubation: 30-34 days. Young fledge at 8 weeks of age.
Nest: Natural and man-made cavities are used for nesting.

Management Considerations: Loss of grassy habitats due to development and conversion of pastures and meadows to row crops have reduced the amount and quality of dense grass habitats, which limits prey availability. Lack of available secure nest sites in grassland habitat is problematic. Extreme cold and deep snow cover may result in the mortality of barn owls attempting to overwinter. Organophosphate insecticides cause poisoning in owls. Protection of grassland habitats and the installation of nest boxes in or adjacent to grassy habitats are effective conservation strategies.