What flies silently in the night, has eyeballs that are 5% of their total body weight, and has ear flaps (operculum) that can be closed to block out sound during the day when they sleep?
It’s the Eastern Screech Owl, the most abundant owl in our area, found in open woodlands, readily accepting parks and suburban neighborhoods. Their breeding territories range from ten to 15 acres in wooded suburban areas, depending upon food supply.
Screech owls are 6 ½ to ten inches tall with a wingspan of 18 to 24 inches and a weight of only four to nine ounces. Male Screech Owls are smaller than females, and are more agile fliers and hunters. However, the female with her larger size and harder strike takes on the duty of defending their nest from potential threats. Screech Owls have two color phases – gray and red, with the gray being the dominant color in Michigan.
Screech Owls have eyes that are tubular which is similar to having telephoto lenses. They have more rods in their eyes, allowing them to see two and a half times better than humans do in low light. With eyes that are fixed in place, they must move their head to see around themselves, the fourteen vertebrae in their neck allowing for a 280-degree rotation of the head.
One of the most fascinating attributes of Screech Owls are their vocalizations. Their contact call is a tremolo with a descending whinny-like quality. Their other call is a low, mellow trembling whistle which last two to four seconds all on the same pitch. The males’ voice is deeper than the females.
Screech Owls have a varied diet, which is why they are successful in so many habitats. They consume mammals including rats, mice, squirrels, and small rabbits. They also eat small birds, normally caught directly from their nocturnal perches or during nocturnal migration. If the habitat provides, they will also eat large numbers of earthworms, insects, crayfish, tadpoles and frogs. Their hunting technique is to sit and wait for small prey to pass by, dropping down and catching the prey with their talons. The Screech Owl’s sense of hearing is acute enough to allow it to locate mammals under heavy vegetation or snow. Their ears are placed asymmetrically on their head, enabling them to use the differences between each ear’s perception of sound to hone in on prey. Additionally, the flight feathers of the Screech Owl have shaggy tips, allowing air to flow smoothly around the wings, which enables them to sneak up silently on prey. Screech-owls regurgitate the undigestible bones, fur, and feathers of their prey in an oval pellet.
Screech Owls are monogamous and remain together for life. They roost and nest in holes and cavities that have an entrance three to eight inches wide. They may also roost in conifers and thick vegetation. Unable to excavate a cavity themselves, they depend on natural tree cavities. Screech Owls readily accept nest boxes. They do not build a nest, the female laying her eggs on whatever debris is at the bottom of the cavity, including wood-chips, twigs, or the cast-off feathers and droppings from a previous year’s nest.
Breeding season for Screech Owls starts in April. Before the breeding season, males defend an area containing several cavities. As part of patrolling their territories, males are known to spend nights in different cavities. The female Screech Owls select the nest site from the cavities in her mate’s territory.
The female will lay two to six white eggs with incubation taking 30 days. Food is supplied by the male to the female while she is on the nest. Once hatched, young owls remain in the nesting cavity for a period of about 30 additional days, after which time they climb out onto nearby branches. After fledging from the nesting cavity, they depend upon their parents for food for 8 to ten weeks. During this time period they tend to roost in a communal group with the female.
What threats do Screech Owls have in our community ? As they fly across streets, their fixed eyes do not pick up peripheral objects, so they are unable to avoid approaching cars. Poisons used for rodents accumulate in their tissue and cause mortality. Eastern Fox squirrels and racoons will eat eggs from nesting cavities, and Great Horned Owls will eat adult Screech Owls. Cats are the largest threat to Screech Owls, eating the mice and rats that owls need for food. Cats also predate on fledgling owls that are not yet able to fly.
Do you have Screech Owls in your neighborhood? Listen for their calls at dusk in the upcoming months and check the trees for cavities. Report your sightings to our store and we can map out the population of these little wonders.