Eastern Screech-Owl (Megascops asio): Identification, Calls & Cavity Use

Megascops asio (Linnaeus, 1758), the Eastern Screech-Owl, is a 121-244 g cavity-nesting owl whose conspicuous ear tufts alter its head outline but have no auditory function; the actual ear openings are buried beneath the facial feathers.

Part of the Complete Owls Guide.

Identification

Visual

This is a small, compact owl, 16-25 cm long, with a short tail, rounded wings, heavy streaking below, and a bark-like dorsal pattern that works exceptionally well against oak, hickory, maple, and sycamore trunks. The bird often sits upright in the mouth of a cavity at dusk, eyes half-closed, relying on immobility rather than concealment by distance.

Two main colour morphs occur. Grey birds dominate much of the northern and western range, with cold grey upperparts crossed by fine black vermiculation. Red morph birds are rich rufous above and below, more frequent in the humid Southeast and lower Mississippi drainage. A brown intermediate occurs but is less common. Morph is not age or sex; it is genetically influenced polymorphism, and paired birds may be of different morphs.

The yellow iris, small size, ear tufts, and heavy vertical underpart streaking separate it from the Northern Saw-whet Owl, which lacks ear tufts and has a rounder, more surprised facial expression. Western Screech-Owl is visually close enough that range and voice are normally decisive. Where both are possible in western Texas, plumage alone should not be treated as conclusive.

Audio

Despite the name, the Eastern Screech-Owl does not usually screech. The primary territorial song is a descending whinny, a tremulous series falling in pitch over 2-3 seconds. A second common vocalisation is an even-pitched monotone trill, typically 3-6 seconds long, used in territorial and pair-contact contexts. In settled suburban territories the trill may be heard from the same tree cavities year after year.

Calls begin well before full darkness, especially in late winter and early spring. Juveniles produce rasping begging calls in late May through July, sometimes from low branches only 2-4 m above ground. These calls draw mobbing from robins, chickadees, titmice, and Blue Jays, which is often the most reliable daytime clue to a roosting adult.

Distribution

The species occupies eastern North America from southern Canada through the Great Lakes, New England, the Atlantic coastal plain, the Southeast, and west to the Great Plains edge. It is absent from most high-elevation Appalachian spruce-fir zones and from treeless intensive agricultural landscapes where cavities are scarce. Northern limits broadly follow the availability of mature deciduous trees and winter prey rather than latitude alone.

It is largely resident. Adults hold territories through winter, and banding recoveries show limited dispersal compared with migratory small owls. Young birds move farther after fledging, but the species is not a regular long-distance migrant.

Habitat

Eastern Screech-Owls are birds of edges and cavities: riparian woodland, old orchards, suburban streets with mature trees, wooded cemeteries, farm shelterbelts, and parks. They tolerate human proximity better than most owls provided cavity trees and prey remain available. A suburban block with old maples, unmown corners, and porch lights attracting insects may support a pair more reliably than a closed, even-aged forest stand.

The critical structural feature is not forest extent but cavity supply. Natural nest and roost sites include old woodpecker cavities, rot holes, broken limbs, and hollow trunks. The species also uses nest boxes readily when entrance diameter and placement exclude larger competitors.

Diet and Hunting

Diet is broad and seasonal. Invertebrates dominate many summer samples: moths, beetles, crickets, cicadas, katydids, and large spiders. In colder months the prey base shifts toward White-footed Mice (Peromyscus leucopus), Meadow Voles (Microtus pennsylvanicus), shrews, small rats, and roosting songbirds. Amphibians, small snakes, crayfish, and fish taken from shallow water are recorded often enough that they should not be treated as exceptional.

The usual method is perch-and-pounce hunting from 1-6 m above ground. The owl watches and listens from a fixed perch, drops almost vertically, then returns to cover. It also hawks insects around lights and woodland openings, a behaviour most visible in August and September when large moths are abundant.

Breeding Biology

Pair formation and territorial calling intensify from January through March. Eggs are laid in cavities from March into May depending on latitude. Clutch size is usually 3-5 eggs, sometimes 2 in poor prey conditions and up to 6 in favourable years. The female incubates for about 26 days while the male delivers prey to the cavity entrance or a nearby perch.

No nest is built. Eggs lie on wood chips, decayed cavity debris, old pellets, or material already present in the hollow. In nest boxes, a layer of coarse wood shavings is useful because bare plywood allows eggs to roll and cool. Young leave the cavity at roughly four weeks, before competent flight, and climb through nearby branches while adults continue provisioning.

Notes

This is one of the most accessible North American owls for careful garden observation, but accessibility does not justify playback at cavities. A bird calling naturally from a territory can be mapped by listening on three or four calm evenings in February. Its position will usually resolve to a cluster of old trees, one of which contains the day roost or nest cavity. That is enough. Close inspection of cavities during the breeding season risks flushing the incubating female and exposing eggs or small young to chilling and corvid predation.

See Also

• Western Screech-Owl
• Barred Owl
• Northern Saw-whet Owl
• American Kestrel
• The Complete Owls Guide
• Why Is an Owl in My Yard?: the species most likely to roost in suburban cavities and nest boxes, in context.
• Eastern vs Western Screech-Owl: yellow-green vs blackish bill plus voice differences; the contact-zone notes for southwestern readers.