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 Today, owls are considered to be creatures of beauty, wise and
mysterious birds that are hunters of the night. Four species of owls
are year-round Illinois residents, the barn owl, screech owl, barred
owl, and great horned owl (also known as the hoot owl).
The barn owl occurs globally but was listed as Illinois-endangered
in 1977 and is currently considered a threatened species in the
state, according to Tara Beveroth, avian researcher and monitoring
coordinator, Illinois Natural History Survey (INHS), Prairie
Research Institute, University of Illinois.
Owls typically call most often at dawn and dusk, but on a clear,
moonlit night with little wind, some may be heard calling
periodically throughout the night. They are territorial creatures
and use their calls to warn others to stay off their turf.
Each owl species has a unique call. Screech owl calls sound like a
horse’s whinny, and the great horned owl, the bird of storybooks,
produces the well-known hooting sound. The barn owl emits a
blood-curdling scream in the darkness, and the barred owl’s call
sounds like, “Who, who cooks for you”?
 As part of the INHS Monitoring for Owls and Nightjars (MOON)
Program, Beveroth’s volunteers learn to distinguish the calls of
owls and nightjars, then drive routes that consist of 10 roadside
stops, listening for 6 minutes at each stop.
“Most owls respond to prerecorded calls, especially during the
breeding season,” Beveroth said. “Sometimes, in response to a
recorded call, barred owls, usually a male and female, can be heard
caterwauling (hooting loudly) to each other. This can be spectacular
to hear.”
Illinois owl species can share a habitat. Barred owls tend to prefer
old bottomland forests, and eastern screech owls are dependent on
forested areas, although they are now also observed in forested
urban areas. Great horned owls can be successful in many different
habitats.
Since their decline, barn owls have come to depend on man-made nest
box structures and barns that fit their nesting needs. They are
considered to be “farmers’ friends” for their mouse-hunting ability;
a family of barn owls can consume as many as 3,000 mice in a season.
Barn owls are known for their ability to capture prey by sound
alone, Beveroth said. They have asymmetrical hearing, with one ear
higher than the other, and depend on their hearing to find rodents
scurrying in foliage on the ground. [to top of second
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Great horned owls are powerful hunters and can take down
medium-sized mammals, including skunks and even other birds of prey.
They also may take over platform nests of hawks high up in tree
branches.
“Their toes are built like a ratchet,” Beveroth said. “Once prey is grasped they
can hold on or perch without expending excess muscle energy.”
Barred owls and screech owls usually nest in tree cavities. When these two
species compete for a nesting site, the larger barred owl will likely win.
Competition for nesting cavities may have pushed screech owls to towns and urban
areas. The screech owl diet is diverse, consisting of insects, rodents, and
small birds.
Owls may engulf entire smaller prey, but because they cannot digest feathers,
fur, scales, or bones, they regurgitate “pellets” of the indigestible materials.
Owl pellets are typically smooth or furry, round, dark masses.
To find owls, look for pellets on the ground near trees or barns. Also look for
“whitewashed” trees, trees with white owl droppings on tree trunks or branches.
For those who are courageous enough to venture into the woods at night under a
full moon, the calls of the owls in the darkness are a welcome reward.
[Lisa Sheppard]
About the Prairie Research Institute:
The Prairie Research Institute (PRI) at the University of
Illinois at Urbana-Champaign comprises the Illinois Natural History
Survey, Illinois State Archaeological Survey, Illinois State
Geological Survey, Illinois State Water Survey, and Illinois
Sustainable Technology Center. PRI provides objective natural and
cultural resource expertise, data, research, service, and solutions
for decision making, the stewardship of Illinois’ resources, and the
public good.
www.prairie.illinois.edu
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