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Overview

Brief Summary

Megascops asio

A small (7-10 inches) owl, the Eastern Screech-Owl is most easily identified by its size, streaked breast, and ear-like feather tufts. This species has two color morphs, one with gray plumage and the other with rusty-red plumage. Male and female Eastern Screech-Owls are similar to one another in all seasons. The Eastern Screech Owl inhabits much of the eastern United States and southern Canada west to the eastern edge of the Rocky Mountains. This species also occurs in northern Mexico south to the Tropic of Cancer. Eastern Screech-Owls are non-migratory in all parts of their range. Eastern Screech-Owls inhabit a variety of deciduous, evergreen, or mixed woodland habitats. This species may also be found in more built-up areas, and can sometimes be found in large urban parks. Eastern Screech-Owls eat a variety of small animals, such as insects, songbirds, and rodents. Like most owls, the Eastern Screech-Owl hunts almost exclusively at night, making it difficult to observe. This owl may be more visible when it is active at dusk or just before sunrise, and birds roosting in trees may be seen during the day with the aid of binoculars. As its name suggests, the Eastern Screech-Owl produces a high-pitched hooting call which may be used to identify this species at night.

Threat Status: Least concern

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Distribution

Geographic Range

Eastern screech-owls are found throughout much of eastern North America, from the Rocky Mountains in the West to the Atlantic coast and from Florida and southern Texas in the south as far north as southern Canada.

Biogeographic Regions: nearctic (Native )

  • Gehlbach, F. 1995. Eastern Screech Owl (Otus asio). The Birds of North America, 165: 1-24.
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Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Resident from southern Saskatchewan (Adam 1987) and southern Manitoba east across southern Canada and northern U.S. to Maine, south through eastern U.S. to San Luis Potosi, southern Texas, Gulf Coast, and southern Florida, west to eastern Colorado.

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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Geographic Range

Eastern screech-owls are found throughout much of eastern North America, from the Rocky Mountains in the West to the Atlantic coast and from Florida and southern Texas in the south as far north as southern Canada.

Biogeographic Regions: nearctic (Native )

  • Gehlbach, F. 1995. Eastern Screech Owl (Otus asio). The Birds of North America, 165: 1-24.
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The eastern screech-owl is found in eastern North America and
northeastern Mexico. Its range extends across southern Saskatchewan,
southern Manitoba, northern Minnesota, northern Michigan, southern
Ontario, southwestern Quebec, and Maine; south through eastern Montana,
eastern Colorado, and Texas to central Nuevo Leon, eastern San Luis
Potosi, and southern Tamaulipas; east to the Gulf Coast and southern
Florida [1,27]. At the western edges of its range, it appears to be
confined by the eastern front ranges of the Rocky Mountains in Wyoming,
Montana, and Colorado [1,13,22].

Distribution of subspecies is as follows:

Rocky Mountain screech-owl: Southeastern Saskatchewan, southern
Manitoba, eastern Montana, and the Dakotas south to eastern Wyoming,
western Nebraska, western Kansas, and northeastern Colorado. Possibly
also breeds in central Alberta, but these birds may be western screech-owl.

Hasbrouck's screech-owl: Central Kansas to Oklahoma and Texas.

Texas screech-owl: Lower Rio Grande to the southern border to Tamaulipas.

Southern screech-owl: Minnesota, peninsular Michigan, southern
Quebec, and southern Maine south to Missouri and northern parts of
Mississippi, Alabama, and Georgia.

Florida screech-owl: Florida and the Gulf Coast west at least to
Louisiana and north to Arkansas [18].
  • 1. Adam, Christopher I. G. 1987. Status of the eastern screech owl in Saskatchewan with reference to adjacent areas. In: Nero, Robert W.; Clark, Richard J.; Knapton, Richard J.; Hamre, R. H., eds. Biology and conservation of northern forest owls: symposium proceedings; 1987 February 3-7; Winnipeg, MB. Gen. Tech. Rep. RM-142. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 268-276. [24601]
  • 13. Fitton, Sam. 1993. Screech-owl distribution in Wyoming. Western Birds. 24: 182-188. [24789]
  • 18. Johnsgard, Paul A. 1988. North American owls. Washington, DC: Smithsonian Institute Press. 295 p. [23301]
  • 22. Marti, Carl D.; Marks, Jeffrey S. 1989. Medium-sized owls. In: Proceedings of the western raptor management symposium and workshop; 1987 October 26-28; Boise, ID. Scientific and Technical Series No. 12. Washington, DC: National Wildlife Federation: 124-133. [22382]
  • 27. Sibley, Charles G.; Monroe, Burt L., Jr. 1990. Distribution and taxonomy of the birds of the world. New Haven, CT: Yale University Press. 1111 p. [22814]

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Regional Distribution in the Western United States

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

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Occurrence in North America

AL AR CO CT DE FL GA IL IN IA
KS KY LA ME MD MA MI MN MS MO
MT NE NH NJ NY NC ND OH OK PA
RI SC SD TN TX UT VT VA WV WI
WY DC


MB ON PQ SK



MEXICO

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Physical Description

Morphology

Physical Description

Eastern screech-owls are small owls, from 16 to 25 cm in length. Females are generally larger than males, which is common in owls. Eastern screech-owls are dichromatic, they come in two distinct colors. They are either gray or reddish, with darker streaking on the body. Both color variations make these owls blend in with the color of surrounding tree bark. They have bold streaking on their breasts, yellow beaks and eyes, relatively large feet with feathered toes, and large "ear" tufts on either side of their head. These feather tufts really have nothing to do with the owl's ears, but they location on the side of the head makes them look like large, erect ears.

Range length: 16 to 25 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: female larger

Average mass: 164.1 g.

Average basal metabolic rate: 0.586 W.

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Physical Description

Eastern screech-owls are small owls, from 16 to 25 cm in length. Females are generally larger than males, which is common in owls. Eastern screech-owls are dichromatic, they come in two distinct color morphs. They are either uniformly gray or uniformly rufous, with darker streaking on the body. Both color morphs make them very difficult to distinguish from surrounding tree bark. They have bold streaking on their breasts, yellow beaks and eyes, relatively large feet with feathered toes, and large "ear" tufts on either side of their head. Eastern screech-owls are distinguished from their close relative western screech-owls, by their yellow bill, descending trill call, and by the rufous coloration of some individuals.

Range length: 16 to 25 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: female larger

Average mass: 164.1 g.

Average basal metabolic rate: 0.586 W.

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Size

Length: 22 cm

Weight: 194 grams

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Ecology

Habitat

Comments: Open woodland, deciduous forest, orchards, woodland/forest edge, swamps, parklands, residential areas in towns, scrub, and riparian woodland in drier regions. Evergreen woodland/ forest little used in northeastern U.S. Roosts in tree hollow, among foliage close to trunk, in rock crevice, old magpie nest, nest box, under eaves, or similar site.

Nests in natural cavity, old woodpecker hole, or bird box, often 1.5-9 m above ground; sites with opening of about 7-20 cm (Voous and Cameron 1989); in Kentucky avoided deep cavities (more than 60 cm) and shallow cavities, used cavities averaged 31 cm deep. In south-central Iowa, the highest use of nest boxes occurred in riparian sites (Iowa Bird Life, 1990).

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Habitat and Ecology

Systems
  • Terrestrial
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Eastern screech-owls have the broadest ecological niche of any North American owl. They are found in virtually all kinds of habitats below about 1500 meters elevation, from urbanized surroundings to boreal forests. They are generally found in wooded areas but do well in urban and suburban areas and do well near humans, often using bird boxes for nesting. These birds are cavity nesters and use natural cavities or those created by other animals.

Range elevation: 1500 (high) m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest ; scrub forest

Other Habitat Features: urban ; suburban

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Cover Requirements

More info for the term: natural

Nesting: Eastern screech-owls nest in natural cavities, woodpecker
holes, nest boxes, and other artificial structures [9]. Within the
oak-hickory forest region, maples, apples (Malus spp.), sycamores
(Platanus occidentalis) with natural cavities, and pines with woodpecker
holes are preferred [16]. In Louisiana eastern screech-owls chose nest
cavities in trees with lianas more often than expected according to
availability [24]. Mean minimum diameter of cavity trees is 12 inches
(30 cm) [10]. Eastern screech-owls usually choose cavities with
openings 3 to 5 inches (7.6-12.7 cm) in diameter. Typically, cavity
height is between 5 and 30 feet (1.5-9 m) above ground [5]. Nest
cavities are usually reused in successive years [11]. Nest boxes are
often reused by the same pair; one female was recorded using the same
box 8 years in a row [37].

Roosting: Eastern screech-owls prefer to roost in natural hollows
protected from rain and snow, and out of direct sunlight. They avoid
hollows used by fox squirrels (Sciurus niger) [7,19]. Roosting hollows
are typically 15 to 20 feet (4.5-6 m) and usually less than 40 feet (12
m) above the ground. Roosting cavity openings are about the same size
as nest cavity openings [7].
  • 7. Craighead, John J.; Craighead, Frank C., Jr. 1969. Hawks, owls and wildlife. Dover Edition. New York: Dover Publications, Inc. 443 p. [24517]
  • 10. DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]
  • 5. Bent, Arthur Cleveland. 1961. Life histories of North American birds of prey. Part 2. New York: Dover Publications, Inc. 482 p. [22362]
  • 9. de la Torre, Julio. 1990. Owls: Their life and behavior. New York: Crown Publishers. 214 p. [24580]
  • 11. DeGraaf, Richard M.; Yamasaki, Mariko; Leak, William B.; Lanier, John W. 1992. New England wildlife: management of forested habitats. Gen. Tech. Rep. NE-144. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 271 p. [19322]
  • 16. Hardin, Kimberly I.; Evans, Keith E. 1977. Cavity nesting bird habitat in the oak-hickory forests--a review. Gen. Tech. Rep. NC-30. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 23 p. [13859]
  • 19. Karalus, Karl E.; Eckert, Allan W. 1974. The owls of North America (north of Mexico). Garden City, NY: Doubleday & Company, Inc. 278 p. [24579]
  • 24. McComb, William C.; Noble, Robert E. 1981. Nest-box and natural-cavity use in three mid-south forest habitats. Journal of Wildlife Management. 45(1): 93-101. [19257]
  • 37. VanCamp, Laurel F.; Henny, Charles J. 1975. The screech owl: its life history and population ecology in northern Ohio. North American Fauna, Number 71. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 65 p. [24787]

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Preferred Habitat

More info for the terms: cover, density, shrubs

Suitable eastern screech-owl habitat seems to be wherever nesting and
roosting cavities are near or adjacent to open areas with available
rodent prey [29]. Eastern screech-owls usually inhabit open woodlands
adjacent to meadows, marshes, or fields; forest clearings; old orchards;
and parks and other open areas in urban or suburban areas [10,9]. They
are more tolerant of human habitation and human activities than other
owls, and are found in or near barns, outbuildings, birdhouses,
hedgerows, and fencerows [19,29]. They are rarely found in swamps or
deep forest habitats [28].

Eastern screech-owls generally prefer areas with widely spaced trees
interspersed with grassy openings [10]. In Connecticut, red maple
woodlands, upland woodland, evergreen hedgerows, and edge habitats were
used by eastern screech-owl more often than expected if habitat choice
were random. Lawns, mixed woods, and evergreen woods were used less
often than would be expected if habitat choice were random. Although
lawns were not a selected habitat, they were a major component of all
monthly home ranges (a monthly home range is the amount of territory
used in the span of a month) [30]. In central Kentucky radio-tagged
eastern screech-owls used woodlots and edges more than expected based on
availability, and used pastures, old fields, and croplands less than
expected [32]. Lynch and Smith [38] reported that eastern screech-owl
abundance in Connecticut was positively related to the amount of natural
area within urban open space (examples include shrubs, old fields, and
marshes). There was also a positive relationship among eastern
screech-owl abundance, total habitat diversity, and the amount of linear
edge. Areas with mixtures of habitats including relatively high amounts
of undisturbed successional communities and edges tended to support many
owls [38]. In the southeastern states, eastern screech-owls are found
up to 4,500 feet (1,371 m) elevation (but are rare at the higher
elevations) [15].

Hunting: Eastern screech-owls usually hunt in grassy openings, fields,
meadows, and along wooded field margins and streams [10].

Home Range: In suburban areas most food gathering trips are less than
330 feet (100 m) round trip. In areas with lower prey density food
trips may be longer [14]. Home range size is related to prey
availability. Smith and Gilbert [30] estimated that the area traversed
in one night (the nightly range) for female eastern screech-owls was the
largest (38 acres [15.5 ha]) from November to February (when prey was
most scarce), was smallest during egg-laying and incubation (13 acres
[5.4 ha]) in March and April, and expanded again in June to 22 acres
(8.9 ha). The larger nightly ranges in winter were thought to reflect a
need to cover greater areas to obtain adequate food. The total home
range of one female was 323 acres (130.9 ha), but she typically hunted
only a small area each night and a larger cumulative portion each month.
Home range was largest while a female was selecting a nest site and
smallest during egg laying, incubation, and care of young. The actual
defended territory included only the area immediately around the nest
cavity [30]. Gehlbach [14] estimated Connecticut home ranges as 9.9 to
14.8 acres (4-6 ha) and Texas home ranges exceeding 74.1 acres (30 ha).

Estimated Population Density: In the Southeast, sampled breeding
density was listed as 2.8 pairs per 100 acres (2.8 pairs/40 ha) [15].
Lynch and Smith [38] observed a range of 1 to 18 eastern screech-owls
per square mile (1-7/sq km); an average of 6 birds per square mile
(2.3/sq km) occurred in 4 suburban areas in Connecticut.
  • 10. DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]
  • 9. de la Torre, Julio. 1990. Owls: Their life and behavior. New York: Crown Publishers. 214 p. [24580]
  • 14. Gehlbach, Frederick R. 1986. Odd couples of suburbia. Natural History. 95(6): 56-64, 66. [24945]
  • 15. Hamel, Paul B.; LeGrand, Harry E., Jr.; Lennartz, Michael R.; Gauthreaux, Sidney A., Jr. 1982. Bird-habitat relationships on southeastern forest lands. Gen. Tech. Rep. SE-22. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 417 p. [15423]
  • 19. Karalus, Karl E.; Eckert, Allan W. 1974. The owls of North America (north of Mexico). Garden City, NY: Doubleday & Company, Inc. 278 p. [24579]
  • 28. Smith, Dwight G. 1993. Eastern screech owls. Bird Watcher's Digest. 16(1): 32-39. [24776]
  • 29. Smith, Dwight G.; Devine, Arnold; Walsh, Dan. 1987. Censusing screech owls in southern Connecticut. In: Nero, Robert W.; Clark, Richard J.; Knapton, Richard J.; Hamre, R. H., eds. Biology and conservation of northern forest owls: symposium proceedings; 1987 February 3-7; Winnipeg, MB. Gen. Tech. Rep. RM-142. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 255-267. [24600]
  • 30. Smith, Dwight G.; Gilbert, Raymond. 1984. Eastern screech-owl home range and use of suburban habitats in southern Connecticut. Journal of Field Ornithology. 55(5): 322-329. [24775]
  • 32. Sparks, Earl J.; Belthoff, James R.; Ritchison, Gary. 1994. Habitat use by eastern screech-owls in central Kentucky. Journal of Field Ornithology. 65(1): 83-95. [23432]
  • 38. Lynch, Patrick J.; Smith, Dwight G. 1984. Census of eastern screech-owls (Otus asio) in urban open-space areas using tape-recorded song. American Birds. 38: 388-391. [24777]

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Associated Plant Communities

More info for the term: hardwood

The eastern screech-owl occupies a wide variety of habitat types [29].
It is commonly associated with open woodlands of oaks (Quercus spp.),
maples (Acer spp.), and hickories (Carya spp.); it is also found in pine
(Pinus spp.) forests and plantations, mixed woodlands, orchards, and
forested wetlands [28]. At the northern and western edges of its range,
the eastern screech-owl occupies riparian woods dominated by hardwoods
including boxelder (Acer negundo), green ash (Fraxinus pennsylvanica),
and bur oak (Quercus macrocarpa) [23]. In South Dakota eastern
screech-owls were found in riparian woods dominated by eastern
cottonwood (Populus deltoides) and willows (Salix spp.), hardwoods
dominated by green ash, boxelder, American elm, and bur oak, and
shelterbelts. Siberian elm (Ulmus pumila) is a common shelterbelt tree
in South Dakota and is used by eastern screech-owls [12]. In Kansas
eastern screech-owls were also observed in shelterbelts [26]. In New
England, eastern screech-owls are found in aspen (Populus spp.), paper
birch (Betula papyrifera), northern hardwoods, red maple (Acer rubrum),
balsam fir (Abies balsamea), eastern hemlock (Tsuga canadensis),
northern red oak (Quercus rubra), eastern white pine (Pinus
strobus)-northern red oak-red maple, and eastern white pine communities
[11]. In South Carolina on the Coastal Plain, eastern screech-owls were
observed in pine and hardwood stands. The managed pine stands were
mostly longleaf pine (P. palustris) and loblolly pine (P. taeda).
Hardwood stands were dominated by gums (Nyssa spp.), baldcypress
(Taxodium distichum), oaks, or red maple [17]. In Louisiana eastern
screech-owls were found in mature mixed bottomland hardwoods dominated
by water oak (Q. nigra), pignut hickory (Carya glabra), American elm
(Ulmus americana), and sugarberry (Celtis laevigata). They also
inhabited cottonwood plantations and riverfront hardwoods dominated by
sweet pecan (Carya illinoiensis), water hickory (C. aquatica),
sugarberry, and waterlocust (Gleditsia aquatica) [24].

REFERENCES :
NO-ENTRY
  • 11. DeGraaf, Richard M.; Yamasaki, Mariko; Leak, William B.; Lanier, John W. 1992. New England wildlife: management of forested habitats. Gen. Tech. Rep. NE-144. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 271 p. [19322]
  • 12. Emmerich, John M.; Vohs, Paul A. 1982. Comparative use of four woodland habitats by birds. Journal of Wildlife Management. 46(1): 43-49. [19283]
  • 17. Harlow, Richard F.; Guynn, David C., Jr. 1983. Snag densities in managed stands of the South Carolina coastal plain. Southern Journal of Applied Forestry. 7(4): 224-229. [12571]
  • 23. Mazur, Kurt M. 1992. Fall food of the eastern screech-owl in Manitoba. Blue Jay. 50(1): 33-35. [24788]
  • 24. McComb, William C.; Noble, Robert E. 1981. Nest-box and natural-cavity use in three mid-south forest habitats. Journal of Wildlife Management. 45(1): 93-101. [19257]
  • 26. Schroeder, Richard L.; Cable, Ted T.; Haire, Sandra L. 1992. Wildlife species richness in shelterbelts: test of a habitat model. Wildlife Society Bulletin. 20(3): 264-273. [22439]
  • 28. Smith, Dwight G. 1993. Eastern screech owls. Bird Watcher's Digest. 16(1): 32-39. [24776]
  • 29. Smith, Dwight G.; Devine, Arnold; Walsh, Dan. 1987. Censusing screech owls in southern Connecticut. In: Nero, Robert W.; Clark, Richard J.; Knapton, Richard J.; Hamre, R. H., eds. Biology and conservation of northern forest owls: symposium proceedings; 1987 February 3-7; Winnipeg, MB. Gen. Tech. Rep. RM-142. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 255-267. [24600]

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Habitat: Cover Types

More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

1 Jack pine
5 Balsam fir
12 Black spruce
14 Northern pin oak
15 Red pine
20 White pine-northern red oak-red maple
21 Eastern white pine
22 White pine-hemlock
23 Eastern hemlock
24 Hemlock-yellow birch
25 Sugar maple-beech-yellow birch
26 Sugar maple-basswood
27 Sugar maple
28 Black cherry-maple
39 Black ash-American elm-red maple
40 Post oak-blackjack oak
42 Bur oak
43 Bear oak
44 Chestnut oak
45 Pitch pine
46 Eastern redcedar
50 Black locust
51 White pine-chestnut oak
52 White oak-black oak-northern red oak
53 White oak
55 Northern red oak
57 Yellow-poplar
58 Yellow-poplar-eastern hemlock
59 Yellow-poplar-white oak-northern red oak
60 Beech-sugar maple
61 River birch-sycamore
63 Cottonwood
64 Sassafras-persimmon
65 Pin oak-sweetgum
72 Southern scrub oak
87 Sweetgum-yellow-poplar
88 Willow oak-water oak-diamondleaf oak
89 Live oak
93 Sugarberry-American elm-green ash
94 Sycamore-sweetgum-American elm
95 Black willow
96 Overcup oak-water hickory
108 Red maple
109 Hawthorn
110 Black oak

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Habitat: Plant Associations

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: bog

K081 Oak savanna
K082 Mosaic of K074 and K100
K084 Cross Timbers
K089 Black Belt
K093 Great Lakes spruce-fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce-fir forest
K097 Southeastern spruce-fir forest
K098 Northern floodplain forest
K099 Maple-basswood forest
K100 Oak-hickory forest
K101 Elm-ash forest
K102 Beech-maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K107 Northern hardwoods-fir forest
K108 Northern hardwoods-spruce forest
K110 Northeastern oak-pine forest
K111 Oak-hickory-pine forest
K112 Southern mixed forest
K113 Southern floodplain forest
K114 Pocosin
K115 Sand pine scrub

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Habitat: Ecosystem

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES12 Longleaf-slash pine
FRES13 Loblolly-shortleaf pine
FRES14 Oak-pine
FRES15 Oak-hickory
FRES16 Oak-gum-cypress
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch

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Habitat: Rangeland Cover Types

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

810 Longleaf pine-turkey oak hills
811 South Florida flatwoods
812 North Florida flatwoods
813 Cutthroat seeps
820 Everglades flatwoods

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Eastern screech-owls have the broadest ecological niche of any North American owl. They are found in virtually all kinds of habitats below about 1500 meters elevation, from urbanized surroundings to boreal forests. They are generally found in wooded areas but do well in urban and suburban areas and acclimatize readily to human presence, often using bird boxes for nesting. These birds are cavity nesters and use natural cavities or those created by other animals.

Range elevation: 1500 (high) m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest ; scrub forest

Other Habitat Features: urban ; suburban

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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Sedentary.

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Trophic Strategy

Comments: Eats mainly mice, shrews, and insects, also other small vertebrates and invertebrates (Terres 1980). Opportunistic, takes whatever is readily available. Caches prey in tree holes and nest boxes.

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Food Habits

Eastern screech-owls eat the most varied diet of any North American owl. Their diet includes large evening active insects, like Lepidoptera and Tettigoniidae, Malacostraca, Oligochaeta, amphibians, Squamata, small mammals, like Sigmodontinae and Vespertilionidae, and small Aves. These owls have symmetrical ears, which suggests that they hunt mainly by using their vision. (Ears that are not symmetrical give owls a better ability to pinpoint the location of prey using only hearing.) They do, however, have excellent hearing as they often capture prey hidden by leaf litter. They hunt by sitting on a tree branch and waiting to see or hear prey. Eastern screech-owls store prey in their nests to eat later or for their young to eat later.

Animal Foods: birds; mammals; amphibians; reptiles; insects; terrestrial non-insect arthropods; terrestrial worms

Foraging Behavior: stores or caches food

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Food Habits

More info for the term: formation

The eastern screech-owl is an opportunistic feeder. Prey species are
primarily small rodents, but numerous other animals are consumed [10].
Norberg [25] stated that insects are the major portion of the diet of
Megascops owls, but since the eastern screech-owl is sedentary it switches to
mammalian and avian prey in winter [37]. The mammalian prey list
includes mice and rats (Muridae), shrews (Soricidae), moles (Talpidae),
flying squirrels (Glaucomys spp.), chipmunks (Tamias spp.), and bats
(Chiroptera). Avian prey includes songbirds, rock dove (Columbia
livia), northern bobwhite (Colinus virginianus), ruffed grouse (Bonasa
umbellus), American woodcock (Scolopax minor), common snipe (Gallinago
gallinago), American kestrel (Falco sparverius), and even other eastern
screech-owls [18]. Eastern screech-owls have killed domestic pigeons,
hens, and ducks with prandial intent [19]. Other vertebrate prey
includes snakes, lizards, frogs, toads, salamanders, and small fish.
Invertebrate prey includes many insects, snails, crayfish, spiders,
scorpions, millipedes, and earthworms [18].

Even though the prey lists are long, a few species form the main diet.
Favored prey includes meadow vole (Microtus pennsylvanicus),
white-footed mouse (Peromyscus leucopus), house mouse (Mus musculus),
and woodrats (Neotoma spp.) [19]. Snyder and Wiley [31] estimated that
year-round prey consumption by eastern screech-owls is 30.7 percent
invertebrates, 0.6 percent lower vertebrates, 65.6 percent mammals, and
3.3 percent birds.

Seasonal Diet: In Michigan pellet analysis during spring and summer
indicated a high proportion of meadow vole, white-footed mouse,
crayfish, and small birds in eastern screech-owl diets [7]. Pellet
analysis must be interpreted with caution, since many invertebrate prey
items do not contribute to pellet formation. In Ohio almost 65 percent
of the food items brought to nest boxes were birds, the majority of
which were migratory songbirds [37].

Craighead and Craighead's [7] analysis of pellets (Michigan study area)
indicated that meadow vole formed the bulk of the eastern screech-owl
winter diet. In a year when meadow vole numbers were lower than
average, a higher percentage of small birds appeared in pellets. In
both years, white-footed mouse were consumed in amounts comparable to
those of meadow voles. Other major pellet components were shrews and
moles [7]. In Ohio fall and winter diets contained 30 percent birds
[37].

Foraging Habits: Eastern screech-owls tend to follow approximately the
same hunting route within the territory, tending to visit previously
successful sites [5]. They usually forage in a perch-and-pounce manner,
taking short flights to capture already-spotted prey. Eastern
screech-owls have been observed to take a position near a bat colony and
capture bats as they leave the colony [39]. Insects are often caught in
flight. Eastern screech-owls also walk on the ground to forage for
insects, particularly night-dormant grasshoppers, and wade into shallow
water after fish and aquatic invertebrates [18,21,37,39].
  • 7. Craighead, John J.; Craighead, Frank C., Jr. 1969. Hawks, owls and wildlife. Dover Edition. New York: Dover Publications, Inc. 443 p. [24517]
  • 10. DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]
  • 5. Bent, Arthur Cleveland. 1961. Life histories of North American birds of prey. Part 2. New York: Dover Publications, Inc. 482 p. [22362]
  • 18. Johnsgard, Paul A. 1988. North American owls. Washington, DC: Smithsonian Institute Press. 295 p. [23301]
  • 19. Karalus, Karl E.; Eckert, Allan W. 1974. The owls of North America (north of Mexico). Garden City, NY: Doubleday & Company, Inc. 278 p. [24579]
  • 21. Marshall, Joe T., Jr. 1967. Parallel variation in North and Middle American screech-owls. Monongraphs of the Western Foundation of Vertebrate Zoology No. 1. Los Angles, CA: Western Foundation of Vertebrate Zoology. 72 p. [24944]
  • 25. Norberg, R. Ake. 1987. Evolution, structure, and ecology of northern forest owls. In: Nero, Robert W.; Clark, Richard J.; Knapton, Richard J.; Hamre, R. H., eds. Biology and conservation of northern forest owls: symposium proceedings; 1987 February 3-7; Winnipeg, MB. Gen. Tech. Rep. RM-142. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 9-43. [24599]
  • 31. Snyder, Noel F. R.; Wiley, James W. 1976. Sexual size dimorphism in hawks and owls of North America. Ornithological Monographs. No. 20. Gainesville, FL: American Ornithologists' Union. 96 p. [24770]
  • 37. VanCamp, Laurel F.; Henny, Charles J. 1975. The screech owl: its life history and population ecology in northern Ohio. North American Fauna, Number 71. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 65 p. [24787]
  • 39. Allen, A. A. 1924. A contribution to the life history and economic status of the screech owl (Otus asio). Auk. 41(1): 1-17. [24778]

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Food Habits

Eastern screech-owls eat the most varied diet of any North American owl. Their diet includes large evening active insects, like moths and katydids, crayfish, earthworms, amphibians, reptiles, small mammals, like mice and bats, and small birds. These owls have symmetrical ears, which suggests that they hunt primarily using their vision. They do, however, have excellent hearing as they often capture prey hidden by leaf litter. They hunt by sitting on a tree branch and waiting to see or hear prey. Eastern screech-owls cache prey in their nests for later consumption by adults or nestlings.

Animal Foods: birds; mammals; amphibians; reptiles; insects; terrestrial non-insect arthropods; terrestrial worms

Foraging Behavior: stores or caches food

Primary Diet: carnivore (Insectivore , Eats non-insect arthropods)

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Associations

Ecosystem Roles

Eastern screech-owls are sometimes the most abundant and important small predator in urban and suburban forested areas. They also deliberately bring live animals, such as Leptotyphlops dulcis into their nests. These animals feed on the ants, flies, and other insects that infest the nest cavity. Crematogaster lineolatus may inhabit the nest cavity of these owls and will repel intruders by spraying irritating secretions and biting.

Mutualist Species:

  • Crematogaster lineolatus
  • Leptotyphlops dulcis

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Predation

Eastern screech-owls watch animal movements near their nest holes very carefully, they are always on the lookout for predators. They are preyed on as adults and fledglings by larger Strigiformes, Accipitridae, and other eastern screech-owls. Eggs and nestlings may be taken by Elaphe obsoleta, Didelphis virginiana, Procyon lotor, and Bassariscus astutus. Eastern screech-owls use alarm calls and will physically attack potential predators that approach their nestlings and fledglings. The colors of eastern screech-owls make them very difficult to see against a bark background, which protects them from predators as well.

Known Predators:

  • owls (Strigiformes)
  • hawks (Accipitridae)
  • black rat snakes (Elaphe_obsoleta)
  • Virginia opossums (Didelphis_virginiana)
  • raccoons (Procyon_lotor)
  • ringtails (Bassariscus_astutus)

Anti-predator Adaptations: cryptic

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Predators

Larger owls prey on eastern screech-owl; the primary predator is the
great horned owl (Bubo virginianus), but others include barred owl
(Strix varia), great gray owl (S. nebulosa), snowy owl (Nyctea
scandiaca), long-eared owl (Asio otus), short-eared owl (A. flammeus),
and common barn owl (Tyto alba). Large hawks also take eastern
screech-owl, but only rarely since hawks are largely diurnal. Other
predators include domestic cat (Felis catus), Mustelids (minks, weasels,
and skunks), northern river otter (Lutra canadensis), bobcat (Lynx
rufus), and domestic dogs (Canis familiaris). Snakes have killed adult
eastern screech-owls (usually because an eastern screech-owl attacked a
snake too large to capture easily) but are more commonly nest predators
[19].
  • 19. Karalus, Karl E.; Eckert, Allan W. 1974. The owls of North America (north of Mexico). Garden City, NY: Doubleday & Company, Inc. 278 p. [24579]

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Ecosystem Roles

Eastern screech-owls are sometimes the most abundant and important small predator in urban and suburban forested areas. They also deliberately bring live animals, such as blind snakes into their nests. These animals feed on the ants, flies, and other insects that infest the nest cavity. Acrobat ants may inhabit the nest cavity of these owls and will repel intruders by spraying irritating secretions and biting.

Mutualist Species:

  • acrobat ants
  • blind snakes

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Predation

Eastern screech-owls are extremely vigilant near their nest holes, perhaps in order to assess predator movements. They are preyed on as adults and fledglings by larger owls, hawks, and other eastern screech-owls. Eggs and nestlings may be taken by black ratsnakes, Virginia opossums, raccoons, and ringtails. Eastern screech-owls use alarm calls and will physically attack potential predators that approach their nestlings and fledglings. Their coloration also makes them cryptic.

Known Predators:

Anti-predator Adaptations: cryptic

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Known predators

Otus asio is prey of:
Strigiformes
Accipitridae
Elaphe obsoleta
Didelphis virginiana
Procyon lotor
Bassariscus astutus

This list may not be complete but is based on published studies.
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Known prey organisms

Otus asio preys on:
non-insect arthropods
Annelida
Arthropoda
Insecta
Amphibia
Reptilia
Aves
Mammalia
Diadophis punctatus

This list may not be complete but is based on published studies.
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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

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Global Abundance

10,000 to >1,000,000 individuals

Comments: Guesstimated number of breeding pairs in Canada in the early 1990s was 10,000-50,000 (Kirk et al. 1995).

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General Ecology

Local population density in suitable habitat ranges from fewer than 1 to several per sq km (Johnsgard 1988). In Ohio, young dispersed an average of only 32 km by the spring following hatching; dispersal was much less in Texas and Kentucky (mean = 4.4 km) studies (Johnsgard 1988, Belthoff and Ritchison 1989). In Kentucky, juveniles settled 2-11 days after departing from natal areas; high mortality rate in juveniles (Belthoff and Ritchison 1989). Generally very sedentary. Home range size varies seasonally. Population fluctuations usually are minor, though die-offs may occur in far north when snow cover is deep and long-lasting (Voous and Cameron 1989).

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Habitat-related Fire Effects

More info for the term: natural

Habitat related fire effects include loss of habitat, change in habitat
structure (which may affect both nesting and hunting), and effects on
the prey base. In the southeastern states a majority of small mammals
thrive in early- to mid-successional habitats which are maintained by
fire or other disturbance [41]. Prey vulnerability depends at least
partly on vegetation structure. Low, open vegetation makes prey easier
to spot, but eastern screech-owls require perches from which to hunt.
Fire-caused wounds may increase decay in large trees, making them more
likely to develop cavities (either natural or excavated).

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Timing of Major Life History Events

More info for the terms: altricial, selection

Diurnal Activity: Eastern screech-owls are rarely active before dusk.
In Ithaca, New York, the earliest recorded time of initiation of feeding
activity was 8:25 p.m.; the latest time feeding ended was 4:15 a.m. [39].

Migration Status: Eastern screech-owls are resident throughout their
range; suggestions that some migration occurs at the northern edge of
the range have not been substantiated [18]. The large majority of adult
birds (87%) were recovered within 10 miles (16 km) of the banding site.
None had moved more than 40 miles (64 km) [37].

Pair Bond: Craighead and Craighead [7] stated that they had no data on
year-round pairing, but they observed birds that appeared to remain
loosely paired over the winter, using the same hunting areas and
roosting sites as during the breeding season. They delimited the
beginning of the breeding season by the selection of a nesting
territory; in Michigan this usually occurs around the end of February
[7].

Nesting: Peak nesting season, when young are in the nest, appears to
coincide with most passerine migration (a rich source of prey) [37]. In
the Southeast, nesting season is from mid-March to late May, peaking in
April [15]. In Michigan earliest egg date was April 18 (1942) [7]. In
New York and New England, egg dates ranged from April 12 to May 18. In
Pennsylvania and New Jersey eggs were present in nests from March 23 to
May 19, and in Florida, eggs were present from March 11 to May 18 [18].
The shortest time between eggs is 48 hours; the time between eggs is
often 72 hours and occasionally longer [19]. Typical clutch sizes are 3
to 5 eggs; clutch sizes range from 1 to 10 [18].

Incubation: Incubation is almost exclusively by the female; if she
leaves the nest to drink or bathe, the male will incubate until she
returns and pushes him away. The male brings food but the female eats
very little during incubation [19]. The incubation period is variable,
lasting from 26 to 32 days [37].

Development of Young: The altricial young are downy, with eyes closed
[19]. The young have been observed shivering almost constantly for the
first 2 weeks of life [5]. The eyes are usually open by the 20th day.
Flight feathers begin coming in around the 25th day. The average time
in the nest is 4 to 5 weeks [7,19]. Fledglings stay on branches near
the nest until full flight is achieved. Even after leaving the nest
tree, fledglings continue to be fed by the parents for up to 5 weeks
after fledging. By the ninth week, fledglings usually begin molting to
the first-winter plumage. In Ohio the overall nesting success rate
(the proportion of active nests that fledged at least one young) was
86.1 percent, and the overall breeding success rate (the proportion of
eggs that resulted in young fledged) was 73.8 percent [37].

Juvenile Dispersal: Family groups begin to split up by late August.
Dispersal, in an apparently random direction, occurs in early fall
[18,19]. In a Connecticut banding study, juvenile dispersal fell into
two groups; juveniles either travelled fewer than 20 miles (32 km) or
much greater distances (a minority). The longest distance recorded for
juvenile dispersal was 185 miles (300 km) [37].

Breeding Age and Longevity: One banding study indicated that at least
25 percent of eastern screech-owls bred as yearlings [37]. In the wild,
the average lifespan for eastern screech-owl in central Texas was
estimated as 3.6 years, although some individuals survived to at least 8
years of age [14]. Captive birds have lived more than 20 years [19].
  • 7. Craighead, John J.; Craighead, Frank C., Jr. 1969. Hawks, owls and wildlife. Dover Edition. New York: Dover Publications, Inc. 443 p. [24517]
  • 5. Bent, Arthur Cleveland. 1961. Life histories of North American birds of prey. Part 2. New York: Dover Publications, Inc. 482 p. [22362]
  • 14. Gehlbach, Frederick R. 1986. Odd couples of suburbia. Natural History. 95(6): 56-64, 66. [24945]
  • 15. Hamel, Paul B.; LeGrand, Harry E., Jr.; Lennartz, Michael R.; Gauthreaux, Sidney A., Jr. 1982. Bird-habitat relationships on southeastern forest lands. Gen. Tech. Rep. SE-22. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 417 p. [15423]
  • 18. Johnsgard, Paul A. 1988. North American owls. Washington, DC: Smithsonian Institute Press. 295 p. [23301]
  • 19. Karalus, Karl E.; Eckert, Allan W. 1974. The owls of North America (north of Mexico). Garden City, NY: Doubleday & Company, Inc. 278 p. [24579]
  • 37. VanCamp, Laurel F.; Henny, Charles J. 1975. The screech owl: its life history and population ecology in northern Ohio. North American Fauna, Number 71. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 65 p. [24787]
  • 39. Allen, A. A. 1924. A contribution to the life history and economic status of the screech owl (Otus asio). Auk. 41(1): 1-17. [24778]

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Life History and Behavior

Behavior

Communication and Perception

Eastern screech-owls have keen senses of hearing and vision which help them to locate prey in dim light. They use a variety of calls to communicate with others. Nestlings and females call softly from within the nest cavity. Both males and females give the "trill" song, which may be used to advertise nest sites, in courting, when arriving at the nest with food, and females use it to ask nestlings to come out of the nest and try flying. Other calls are hoots, rasps, chuckle-rattles, barks, and screeches. These calls generally indicate some degree of alarm or anxiety.

Communication Channels: visual ; tactile ; acoustic

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Communication and Perception

Eastern screech-owls have acute senses of hearing and vision which help them to locate prey in dim light. They use a variety of vocalizations. Nestlings and females call softly from within the nest cavity. Both males and females give the "trill" song, which may be used to advertise nest sites, in courting, when arriving at the nest with food, and to call nestlings out of the nest for fledging. Other calls are hoots, rasps, chuckle-rattles, barks, and screeches. These calls generally indicate some degree of alarm or anxiety.

Communication Channels: visual ; tactile ; acoustic

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Life Expectancy

Lifespan/Longevity

An eastern screech-owl lived in the wild for 14 years and 2 months, though most probably live for much less than this. It is estimated that only 30 to 50% of young from one year survive into the next year.

Range lifespan

Status: wild:
14 (high) years.

Average lifespan

Status: wild:
248 months.

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Lifespan/Longevity

An eastern screech-owl lived in the wild for 14 years and 2 months, though most probably live for much less than this. It is estimated that only 30 to 50% of young from one year survive into the next year.

Range lifespan

Status: wild:
14 (high) years.

Average lifespan

Status: wild:
248 months.

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Lifespan, longevity, and ageing

Maximum longevity: 20.7 years Observations: Animals in captivity may live up to 20 years. In the wild, the average longevity has been estimated at 3.6 years (http://www.fs.fed.us/database/feis/).
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Reproduction

Eggs: March-May (April-May in north). Clutch size usually is 4-5 in north, 3 in Florida; increases south to north, and east to west. Incubation is mainly/entirely by female, 3-4 weeks. Young are tended by both parents, leave nest at 30-32 days; usually one or both parents roost with young for several weeks after fledging. Most breed in first year. In Kentucky, juveniles dispersed in mid-July, an average of 55 days after fledging (Belthoff and Ritchison 1989).

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Most eastern screech-owls form pair bonds for life with individuals of the same age, although some males have more than one mate. Both males and females crouch and trill when their mate approaches.

Mating System: monogamous ; polygynous

Eastern screech-owl females lay eggs over a period of days to more than a week and do not begin full-time incubation until the last egg is laid. Because of this, eggs laid first also develop and hatch first. With larger broods, where newly hatched owlets may be up to 8 days behind their nestmates, younger nestlings tend to be killed accidentally or by their siblings. From 2 to 7 eggs, usually 3 or 4, are laid in a large nest cavity. They are incubated for 26 (eggs laid last) to 34 days (earlier eggs), with an average of 30 days of incubation.

Breeding interval: Breeding occurs once a year, usually, but a second clutch may be attempted in areas with dense resources.

Breeding season: Breeding occurs from February through March and perhaps later.

Range eggs per season: 2 to 7.

Average eggs per season: 3.5.

Range time to hatching: 26 to 34 days.

Range time to independence: 8 to 10 weeks.

Average age at sexual or reproductive maturity (female): 1 years.

Average age at sexual or reproductive maturity (male): 1 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (Internal )

Average eggs per season: 4.

Average age at sexual or reproductive maturity (male)

Sex: male:
365 days.

Average age at sexual or reproductive maturity (female)

Sex: female:
365 days.

Eastern screech-owl females incubate the eggs and brood the young. Males feed females and guard nest cavities during incubation and brooding. The young leave the nest at about 28 days old and remain with the parents until they are 8 to 10 weeks old. Both parents feed the young during this period.

Parental Investment: altricial ; male parental care ; female parental care

  • Gehlbach, F. 1995. Eastern Screech Owl (Otus asio). The Birds of North America, 165: 1-24.
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Most eastern screech-owls form pair bonds for life with individuals of the same age. Some mate switching occurs after unsuccessful nesting attempts and some males have been observed nesting simultaneously and sequentially with more than one female. Both males and females crouch and trill when their mate approaches.

Mating System: monogamous ; polygynous

Eastern screech-owl females lay eggs over a period of days to more than a week and generally do not begin full-time incubation until the last egg is laid. As a result, eggs laid first also develop and hatch first. With larger broods, where newly hatched young may be developmentally up to 8 days behind their nestmates, younger nestlings tend to be killed accidentally or by their siblings. From 2 to 7 eggs, usually 3 or 4, are laid in a large nest cavity. They are incubated for 26 (eggs laid last) to 34 days (earlier eggs), with an average of 30 days of incubation.

Breeding interval: Breeding occurs once a year, usually, but a second clutch may be attempted in areas with dense resources.

Breeding season: Breeding occurs from February through March and perhaps later.

Range eggs per season: 2 to 7.

Average eggs per season: 3.5.

Range time to hatching: 26 to 34 days.

Range time to independence: 8 to 10 weeks.

Average age at sexual or reproductive maturity (female): 1 years.

Average age at sexual or reproductive maturity (male): 1 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (Internal )

Average eggs per season: 4.

Average age at sexual or reproductive maturity (male)

Sex: male:
365 days.

Average age at sexual or reproductive maturity (female)

Sex: female:
365 days.

Eastern screech-owl females incubate the eggs and brood the young. Males feed females and guard nest cavities during incubation and brooding. The young leave the nest at about 28 days old and remain with the parents until they are 8 to 10 weeks old. Both parents feed the young during this period.

Parental Investment: altricial ; male parental care ; female parental care

  • Gehlbach, F. 1995. Eastern Screech Owl (Otus asio). The Birds of North America, 165: 1-24.
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Megascops asio

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 10 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNTTCGTAATAATCTTCTTCATAGTAATACCAATCATGATCGGGGGATTTGGAAACTGATTAGTCCCACTGATAATCGGAGCCCCAGACATGGCCTTCCCCCGCATAAACAACATAAGCTTTTGACTACTCCCACCATCATTCCTGCTCTTACTAGCCTCCTCTACAGTAGAAGCTGGGGCAGGCACTGGGTGAACAGTATACCCCCCATTGGCCAGCAACCTAGCCCACGCCGGGGCCTCAGTTGACCTCGCCATCTTCTCATTACATCTAGCCGGGGTGTCATCTATCTTAGGTGCAATCAACTTTATCACCACTGCCATCAACATAAAACCCCCATCCCTAACCCAATACCAAACCCCCCTATTTGTATGATCAGTCCTCATCACTGCTATCCTCCTCCTACTATCCCTCCCAGTACTCGCTGCAGGCATCACCATGTTGCTAACGGACCGCAACCTGAACACTACGTTCTTTGACCCTGCTGGCGGAGGCGACCCTGTATTATACCAGCACCTCTTCNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
-- end --

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Statistics of barcoding coverage: Megascops asio

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 13
Specimens with Barcodes: 16
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

Canada

Rounded National Status Rank: N4 - Apparently Secure

United States

Rounded National Status Rank: N5 - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

Reasons: Species is abundant and widespread.

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Butchart, S. & Symes, A.

Contributor/s

Justification
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
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Eastern screech-owls may suffer as a result of deforestation and the loss of appropriate nesting cavities and prey populations. They are relatively common throughout their range, though, and are not currently threatened.

IUCN Red List of Threatened Species: least concern

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: appendix ii

State of Michigan List: no special status

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The eastern screech-owl is listed as a species of special concern on the
American Ornithologists' Union Blue List. It was first blue-listed in
1981, and was listed again in 1982 and 1986. Numbers of eastern
screech-owls have been reported as declining on the Hudson-Delaware,
southern Atlantic Coast, and in Appalachian and mid-western prairie
regions [34].
  • 34. Tate, James, Jr. 1986. The Blue List for 1986. American Birds. 40(2): 227-235. [24324]

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Eastern screech-owls may suffer as a result of deforestation and the loss of appropriate nesting cavities and prey populations. They are relatively common throughout their range, though, and are not currently threatened.

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: appendix ii

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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Population

Population Trend
Increasing
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Threats

Degree of Threat: D : Unthreatened throughout its range, communities may be threatened in minor portions of the range or degree of variation falls within natural variation

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Management

Global Protection: Unknown whether any occurrences are appropriately protected and managed

Comments: Probably abundant in many managed areas, no details.

Needs: None.

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Management Considerations

More info for the terms: natural, presence

Population Status: Census of eastern screech-owl by song playback
provides a quick and relatively easy method to obtain accurate numbers
[29]. Eastern screech-owl is common in the eastern United States, where
it is often the most common raptor [10,29]. Eastern screech-owl
population densities vary with the relative proportion of woodland cover
in an area [29]. In Connecticut long-term survey data indicated a
decline in eastern screech-owl populations in the 1970's and 1980's,
possibly as a result of increased habitat fragmentation and conversion
of open woods to residential areas [38]. In Ohio the eastern
screech-owl population fluctuated during the 30 years prior to 1975, but
no long-term trend was apparent in owls studied in suitable habitat.
The estimated annual recruitment needed to maintain population size is
2.21 fledglings per nesting pair. Eastern screech-owls have probably
increased with the opening up of dense forest but may be threatened by
increasing conversion of woods to residential areas [37]. The increase
in early successional forest area in the latter half of the twentieth
century, largely due to abandonment of agricultural lands, may benefit
eastern screech-owls. Management considerations for maintenance of
populations include provision of natural and artificial cavities and
preservation of woodlots in suburban areas [38]. Recommended size for
eastern screech-owl nest boxes: floor 8 inches by 8 inches (20 cm X 20
cm), cavity depth 8 to 10 inches (20-24 cm), and an entrance hole 3
inches (7.5 cm) in diameter [16].

Pesticide Accumulation: In the early 1970's eggshell thinning and DDE
and PCB levels in eggs were found to be relatively low for eastern
screech-owls. It was suggested that the consumption of rodents (lower
trophic levels) prior to egg-laying contributed to the relatively low
pesticide loads in eggs. Consumption of birds (higher trophic levels)
increased after eggs were incubated, and thus did not contribute to egg
pesticide loads [37]. Other pesticides have not been investigated in
relationship to eastern screech-owl.

Predator-Prey Relationships: As a general rule, predators that are
specialized on small rodents tend to destabilize rodent population
cycles, whereas generalized predators tend to have a stabilizing effect,
sometimes suppressing cycles altogether. The eastern screech-owl is
more generalist in its effects on rodent populations [25]. Even though
eastern screech-owls sometimes prey heavily on songbirds, they are more
likely to help keep rodent and insect populations in check [19].
Orchard owners reported that putting up nest boxes for screech-owls
resulted in a decrease in rodent damage to orchard trees [5]. Eastern
screech-owls commonly nest in boxes put up for wood ducks (Aix sponsa),
American kestrels, squirrels, and purple martins (Progne subis) and will
even attempt to nest in mailboxes. Wood ducks often use nest boxes
after eastern screech-owls have left the nest; VanCamp and Henny [37]
suggested that wood duck nesting success is enhanced by eastern
screech-owl presence because owls discourage the usurpation of nest
boxes by European starlings (Sternus vulgaris).

Mortality Rates and Causes of Mortality: Mortality rate for the eastern
screech-owl was estimated as 69.5 percent the first year; eastern
screech-owls over 1 year old experience approximately 34 percent annual
mortality [37]. Predation accounts for substantial adult mortality
[37]. Collision with motor vehicles is also a major cause of mortality.
Other causes include shooting (which has become less frequent since
legal protection of raptors was enacted), electrocution, collision with
windows, or entrapment in buildings, and drowning (apparently these owls
take many baths and can become waterlogged and drown in rain barrels)
[18]. There is a small amount of sibling cannibalism, usually after
accidental injury to a nestling [19]. In Michigan nest loss due to fox
squirrels (Sciurus niger), which usually then appropriate the nest
hollow, has been observed [7].

REFERENCES :
NO-ENTRY
  • 7. Craighead, John J.; Craighead, Frank C., Jr. 1969. Hawks, owls and wildlife. Dover Edition. New York: Dover Publications, Inc. 443 p. [24517]
  • 10. DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]
  • 5. Bent, Arthur Cleveland. 1961. Life histories of North American birds of prey. Part 2. New York: Dover Publications, Inc. 482 p. [22362]
  • 16. Hardin, Kimberly I.; Evans, Keith E. 1977. Cavity nesting bird habitat in the oak-hickory forests--a review. Gen. Tech. Rep. NC-30. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 23 p. [13859]
  • 18. Johnsgard, Paul A. 1988. North American owls. Washington, DC: Smithsonian Institute Press. 295 p. [23301]
  • 19. Karalus, Karl E.; Eckert, Allan W. 1974. The owls of North America (north of Mexico). Garden City, NY: Doubleday & Company, Inc. 278 p. [24579]
  • 25. Norberg, R. Ake. 1987. Evolution, structure, and ecology of northern forest owls. In: Nero, Robert W.; Clark, Richard J.; Knapton, Richard J.; Hamre, R. H., eds. Biology and conservation of northern forest owls: symposium proceedings; 1987 February 3-7; Winnipeg, MB. Gen. Tech. Rep. RM-142. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 9-43. [24599]
  • 29. Smith, Dwight G.; Devine, Arnold; Walsh, Dan. 1987. Censusing screech owls in southern Connecticut. In: Nero, Robert W.; Clark, Richard J.; Knapton, Richard J.; Hamre, R. H., eds. Biology and conservation of northern forest owls: symposium proceedings; 1987 February 3-7; Winnipeg, MB. Gen. Tech. Rep. RM-142. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 255-267. [24600]
  • 37. VanCamp, Laurel F.; Henny, Charles J. 1975. The screech owl: its life history and population ecology in northern Ohio. North American Fauna, Number 71. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 65 p. [24787]
  • 38. Lynch, Patrick J.; Smith, Dwight G. 1984. Census of eastern screech-owls (Otus asio) in urban open-space areas using tape-recorded song. American Birds. 38: 388-391. [24777]

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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

There are no negative effects of eastern screech-owls on humans.

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Economic Importance for Humans: Positive

Eastern screech-owls may help to control the populations of potential pests such as mice and some insects.

Positive Impacts: controls pest population

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Economic Importance for Humans: Negative

There are no negative effects of eastern screech-owls on humans.

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Economic Importance for Humans: Positive

Eastern screech-owls may help to control the populations of potential pests such as mice and some insects.

Positive Impacts: controls pest population

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Wikipedia

Eastern screech owl

The eastern screech owl (Megascops asio) is a small owl that is relatively common in Eastern North America, from Mexico to Canada.[1][2] This species is native to most wooded environments of its distribution and, more so than any other owl in its range, has adapted well to manmade development, although it frequently avoid detection due to its strictly nocturnal habits.[3]

Description[edit]

Illustration of the owl by Audubon

Adults range from 16 to 25 cm (6.3–10 in) in length and weigh 121-244 grams (4.3-8.6 oz).[4] Among the differently sized races, length can average from 19.5 to 23.8 cm (7.7 to 9.4 in). The wingspan can range from 46 to 61 cm (18 to 24 in). In Ohio, male owls average 166 g (5.9 oz) and females 194 g (6.8 oz) while in central Texas, they average 157 g (5.5 oz) and 185 g (6.5 oz), respectively.[5][6] They have either rusty or dark gray intricately patterned plumage with streaking on the underparts. Mid-sized by screech-owl standards, these birds are stocky, short-tailed (tail averages from 6.6 to 8.6 cm (2.6 to 3.4 in) in length) and broad-winged (wing chord averages from 14.5 to 17 cm (5.7 to 6.7 in)) as is typical of the genus. They have a large round head with prominent ear tufts, yellow eyes and a yellowish bill, which measures on average 1.45 cm (0.57 in) in length. The feet are relatively large and powerful compared to more southern screech owls and are typically feathered down to the toes, although the southernmost populations only have remnant bristles rather than full feathering on the legs and feet.

Two color variations are referred to as "red or rufous morphs" and "gray morphs" by bird watchers and ornithologists. Rusty birds are more common in the southern parts of the range; pairings of the two color variants do occur. While the gray morph provides remarkably effective camouflage amongst the bark of hardwood trees, red morphs may find security in certain pine trees and the colorful leaves of changing deciduous trees. The highest percentage of red morph are known from Tennessee (79% of population) and Illinois (78% of population). A rarer "brown morph" is known, recorded exclusively in the south (i.e. Florida), which is may be the occasional product of hybridation between the morphs. In the state of Florida, brown morphs are typically reported in the more humid portions of the state, whereas they appear to be generally absent in the northern and northwestern parts of the state. A paler gray variation (sometimes bordering on a washed-out, whitish look) also exists in western Canada and the north-central United States.[7]

Confusion Species[edit]

In the closely related western screech owl (Megascops kennicottii), they are no "morphs", as all owls of the species are gray. Outside of "red morph" coloration, the western screech owl is of almost exactly the same general appearance and size as the eastern. The only reliable distinguishing features are the bill color, which is considerably darker (often a black-gray) in the western and olive-yellow in the eastern, and their different voices. The eastern and western screech owls overlap in the range in the Rio Grande valley at the Texas-Mexico border and the riparian woods of the Cimarron tributary of the Arkansas River on the edge of southern Great Plains.[3] Other somewhat similar species that may abut the eastern screech owl's range in its western and southernmost distribution, like the Middle American screech owl (Megascops guatemalae; formerly called "vermiculated screech owl"), whiskered screech owl (Megascops trichopsis) and the flammulated owl (Psiloscops flammeolus), are distinguished by their increasingly smaller body and foot size, different streaking pattern on breast (bolder on the whiskered, weaker on the others), different bare part coloration and distinctive voices. Through much of the eastern United States, eastern screech owls are essentially physically unmistakable, other owls with ear tufts being much larger and different colored and the only other small owl, the northern saw-whet owl (Aegolius acadius) being even smaller with no ear tufts, a more defined facial disc and browner overall color.[7]

Subspecies[edit]

Five subspecies are typically treated for the eastern screech owl but the taxonomy in the species is considered "muddled". Much of the variation may be considered clinal, as predictably, the size tends to decrease from north to south and much of the color variation is explainable by adaptation to habitat.

  • M. a. asio (Linnaeus, 1758). Includes previously described races no longer considered valid such as M. a. carolinensis, M. a. naevius and M. a. striatus. Resident from eastern Minnesota to southwestern Quebec and southern New Hampshire south to Missouri, Tennessee and northern South Carolina. Dorsal color is cold gray; red morph common (~39% of overall population).[8] The nominate's markings are coarse and sparse and its toes are densely feathered. primary song has a terminal tremulous whinny. This is a medium-to-large race, measuring 14 to 18 cm (5.5 to 7.1 in) in wing chord length. The owls of southern Ontario are on the larger end of the scale, of similar size to the relatively big owls of Colorado and Wyoming.[9]
  • M. a. maxwelliae (Ridgway, 1877). Includes M. a. swenki. Resident from central Montana, southeastern Saskatchewan, and southern Manitoba south to western Kansas. This race is similar to M. a. asio but dorsal color tends to be a paler gray, the ventrum being whiter and less heavily marked and red morphs tending to paler and rarer (~7% of population[8]). With a wing chord length of 15 to 18 cm (5.9 to 7.1 in), this is the largest race in average linear measurements.[10]
  • M. a. hasbroucki (Ridgway, 1914). Replacement name for the formerly described M. a. trichopsis. This subspecies is a resident from Oklahoma panhandle and southern Kansas south to Edwards Plateau of central Texas. This subspecies is also similar to M. a. asio but the dorsal color is buffy gray, the red morph being rare (~5% of population), and markings coarse and dense. This race averages at a similar size as the first two, at 14 to 18 cm (5.5 to 7.1 in) in wing chord length.
  • M. a. mccallii (Cassin, 1854). This includes previously described races like M. a. enano and M. a. semplei. Resident from southern Texas (Big Bend to lower Rio Grande Valley) and northwestern Chihuahua and northern Coahuila southeast to eastern San Luis Potosí. This race is similar to M. a. hasbroucki but its markings fine and dense so the dorsum looks heavily mottled, with red morph being rare (apparently entirely absent in south Texas). Its body size is smaller than the northern races, with a wing chord length of 13 to 17 cm (5.1 to 6.7 in). Unlike other subspecies, the primary song of M. a. mccallii lacks a terminal whinny.
  • M. a. floridanus (Ridgway, 1873). Resident in Florida and southern Georgia west through Gulf Coast states to western Louisiana and north in Mississippi River valley to southeastern Arkansas. This race has a dorsal color that's often rusty-brown (red morph equally common), with fine and dense markings. As described above, this subspecies may come in a true "brown morph". It is the smallest race of eastern screech owl, ranging in wing chord length from 13 to 16 cm (5.1 to 6.3 in).

Habitat[edit]

Screech owls can easily avoid detection during the day due to their effective camouflage amongst the bark of deciduous trees

Eastern screech owls inhabit open mixed woodlands, deciduous forests, parklands, wooded suburban areas, riparian woods along streams and wetlands (especially in drier areas), mature orchards, and woodlands near marshes, meadows, and fields. They try to avoid areas known to have regular activity of larger owls, especially great horned owls (Bubo virginianus). Their ability to live in heavily developed areas outranks even the great horned and certainly the barred owl (Strix varia); screech owls also are considerably more successful in the face of urbanization than barn owls (Tyto alba) following the conversion of what was once farmland.[3] Due to the introduction of open woodland and cultivated strips in the Great Plains, the range of eastern screech owls there has expanded.[3] Eastern screech owls have been reported living and nesting in spots such as along the border of a busy highway and on the top of a street light in the middle of a busy town square. In such urban environments, they often met their dietary needs via introduced species that live close to man such as house sparrows (Passer domesticus) and house mice (Mus musculus).[3] They occupy the greatest range of habitats of any owl east of the Rockies. Eastern screech owls roost mainly in natural cavities in large trees, including cavities open to the sky during dry weather. In suburban and rural areas, they may roost in manmade locations such as behind loose boards on buildings, in boxcars, or on water tanks. They will also roost in dense foliage of trees, usually on a branch next to the trunk, or in dense scrubby brush. The distribution of the species is largely concurrent with the distribution of eastern deciduous woodlands, probably discontinuing at the Rocky Mountains in the west and in the northern Mexico in the south due to the occupation of similar niches by other screech owls and discontinuing at the start of true boreal forest because of the occupation of a similar niche by other small owls (especially boreal owls (Aegolius funereus)). Eastern screech owls may be found from sea level up to 1,400 m (4,600 ft) in elevation in the eastern Rocky Mountains and up to 1,500 m (4,900 ft) in the eastern Sierra Madre Oriental Mountains, although their altitudinal limits in the Appalachian Mountains, near the heart of their distribution, is not currently known.[3][11]

Behavior[edit]

Eastern screech owls are strictly nocturnal, roosting during the day in cavities or next to tree trunks. They are quite common, and can often be found in residential areas. However, due to their small size and camouflage, they are much more frequently heard than actually seen. These owls are frequently heard calling at night, especially during their spring breeding season. Despite their name, this owl (nor most "screech-owls") doesn't truly screech. The eastern screech owl's call is an eerie tremolo with a descending, whinny-like quality. They also a monotone purring trill lasting 3–5 seconds. Their voice is unmistakable and follows a noticeably different phrasing than that of the Western Screech Owl. The lugubrious nature of the eastern screech owl's call has warranted description such as "A most solemn graveyard ditty, the mutual consolation of suicide lovers remembering the pangs and delights of the supernal love in the infernal groves, Oh-o-o-o, had I never been bor-r-r-n. (James Hubbard Langille, 1884).[3]

Breeding[edit]

A juvenile eastern screech owl.

Their breeding habitat is deciduous or mixed woods in eastern North America. Usually solitary, they nest in a tree cavity, either natural or excavated by a woodpecker. Holes must have a 7 to 20 cm (2.8 to 7.9 in) entrance to accommodate this owl. Usually they fit only in the holes excavated by northern flickers (Colaptes auratus) or pileated woodpeckers (Dryocopus pileatus), as apparently the mid-sized red-bellied woodpecker (Melanerpes carolinensis) make holes that are not large enough to accommodate them.[12] Orchards, which often have trees with crevices and holes as well as meadow voles (Microtus pennsylvanicus), a dietary favorite, are often a preferred nesting habitat.[3] Eastern screech owls will also use nesting boxes erected by humans. Although some people put up nest boxes meant for screech owls, the owls will also take over nest boxes meant for others, such as those for wood ducks (Aix sponsa), house put up for purple martins (Progne subis) and dovecotes put up for rock pigeons (Columba livia), occasionally killing and consuming at least the latter two in the process of taking over the nest box. In a 9 year study comparing the breeding success of eastern screech owls nesting in natural cavities and nesting in nest boxes showed that the fledging rate was essentially the same, although in some years up to 10% more success in the natural cavities.[12] Depending on the origins of the hole being used, eastern screech owl nests have been recorded at anywhere from 1.5 to 25 m (4.9 to 82.0 ft) off the ground.[3] Like all owls, these birds do not actually build a nest; instead, females lay their eggs directly on the bare floor of the nest hole or on the layer of fur and feathers left over from previous meals that lines the bottom of its den. Breeding pairs often return to the same nest year after year.[13]

This species commences egg laying on average about two months after great horned owls but about two weeks before American kestrels (Falco sparveius) and almost throughout the range lays its first egg at some point in April.[3] Eggs are laid at two day intervals and incubation begins after laying of the first egg. Eggs vary in size in synch with their ultimate body size, ranging from an average of 36.3 mm × 30.2 mm (1.43 in × 1.19 in) in the Northern Rockies to 33.9 mm × 29.2 mm (1.33 in × 1.15 in) in south Texas.[3] From 1 to 6 eggs have been recorded per clutch, with an average of 4.43 in Ohio, 3 in Florida and 4.56 in the north-central United States.[14][15] The incubation period is about 26 days and the young reach the fledging stage at about 31 days old. Females do most of the incubating and brooding but males will also occasionally take shifts. As is the typical division of labor in owls, the male provides most of the food while the female primarily broods the young, and they will stockpile food during the early stages of nesting, although the male tends to work hard nightly because many nestlings often appear to live almost entirely off of freshly caught insects and invertebrates. The male's smaller size make it a superior in its nimbleness, which allows it to caught insects and other swift prey.[3][11] Eastern screech owls are single brooded, but may re-nest if the first clutch is lost especially towards the southern end of its range. When the young are small, the female tears the food apart for them. The female, with her larger size and harder strike, takes on the duty of defending the nest from potential threats and even humans may be aggressively attacked, sometimes resulting in them drawing blood from the head and shoulders of human passers-by.[3]

Feeding habits[edit]

Fuertes portrait of a red and gray morph screech owl.

Like most predators, eastern screech owls are opportunistic hunters. Due to the ferocity and versatility of their hunting style, early authors nicknamed eastern screech owls "feathered wildcats".[16] In terms of ecological niche, they have no easy ecological equivalent in Europe, perhaps the closest being the little owl (Athene noctua), the similar looking Eurasian scops owl (Otus scops) being smaller and weaker and the long-eared owl (Asio otus) more fully dependent on rodents. It has been theorized that the success of eastern screech (and western screech) owls in North America is the reason why long-eared owls are much more restricted to limited northern forest habitat in North America than they are in Europe.[3] Eastern screech owls hunt from dusk to dawn, with most hunting being done during the first four hours of darkness. A combination of sharp hearing and vision is used for prey location. These owls hunt mainly from perches, dropping down onto prey. Occasionally, they will also hunting by scanning through the treetops in brief flights or hover to catch prey. This owl mainly hunts in open woodlands, along the edges of open fields or wetlands, or makes short forays into open fields. When prey is spotted, the owl dives quickly and seizes it in its talons. Small prey will usually be swallowed whole on the spot, while larger prey is carried in the bill to a perch and then torn into pieces. An eastern screech owl will tend to frequent areas in its home range where it hunted successfully on previous nights. The eastern screech owl's sense of hearing is so acute that it can even locate mammals under heavy vegetation or snow. The bird's ears (as opposed to its ear tufts) are placed asymmetrically on its head, enabling it to use the differences between each ear's perception of sound to home in on prey. Additionally, the feathers the eastern screech owl uses to fly are serrated at their tips. This muffles the noise the bird makes when it flaps its wings, enabling it to sneak up on prey quietly. Both the specialized ear placement and wing feathers are a feature shared by most living owl species to aid them in hunting in darkness.[13]

During the breeding season, large insects are favored in their diet, with invertebrates often comprising more than half of the owls' diet. Some regularly eaten insects include beetles, moths, crickets, grasshoppers and cicadas, although they will likely consume any commonly available flying insect. Also taken are crayfish, snails, spiders, earthworms, scorpions, leeches, millipedes and centipedes. Small mammals, ranging in size from shrews to young rabbits (Sylvilagus ssp.), are regular prey and almost always become the owl's primary food during winter. Small rodents such as microtine rodents and mice comprise about 67% of mammals taken, although rodents of a similar weight to the owl, such as rats and squirrels (especially the red squirrel (Tamiasciurus hudsonicus)) are also taken. Jumping mice (Zapus ssp.), chipmunks, moles and bats (especially the little brown bat (Myotis lucifugus)) may be taken occasionally. Small birds such as chickadees (Poecile ssp.), swallows, sparrows and warblers are the most common avian prey and such species are normally caught directly off of their nocturnal perches or during nocturnal migration. In Ohio, the most commonly reported avian prey species, and most common stored food items behind meadow voles, were yellow-rumped warblers (Setophaga coronata) and white-throated sparrows (Zonotrichus albicollis).[14] Abundant mid-sized avian or largish passerine prey are also not uncommon foods, such as mourning doves (Zenaida macroura), downy woodpeckers (Picoides pubescens), northern flickers, blue jays (Cyanocitta cristata), American robins (Turdus migratorius), European starling (Sturnus vulgaris), red-winged blackbirds (Agelaius phoeniceus) and common grackles (Quiscalus quiscula). However, larger avian prey are sometimes caught, including northern bobwhite (Colinus virginianus) and American woodcocks (Scolopax minor) and even rock pigeons and ruffed grouse (Bonasa umbellus), most likely young or fledgling aged birds but all of which are likely to be heavier than the screech owls themselves. All told, more than 100 species of bird have been hunted by eastern screech owls. Irregularly, small fish, small snakes (i.e. Heterodon ssp.), lizards, baby soft-shelled turtles (Apalone ssp.), small frogs (i.e. tree frogs and northern leopard frogs (Lithobates pipiens)), toads, newts and salamanders are also preyed upon. They have even been observed hunting for fish at fishing holes made by people or cracks in ice at bodies of water during winter. The most commonly reported fish prey in Ohio were American gizzard shad (Dorosoma cepedianum) and green sunfish (Lepomis cyanellus).[14] Brown bullheads (Ameiurus nebulosus) have been captured by eastern screech owls along coastal areas during winter.[3]

From hundreds of prey remains from Ohio, 41% were found to be mammals (23% of which were mice or voles), 18% were birds and 41% were insects and other assorted invertebrates. Of vertebrates taken in the nesting season, 65% were birds (of approximately 54 species), 30% were mammals (11% meadow voles; 8% each of house mice and deermice (Peromyscus ssp.)), 3% were fish and less than 2% were reptiles and amphibians.[14] In Michigan, amongst winter foods 45-50% were meadow voles, 45% were white footed mice (Peromyscus leucopus) and 1-10% were birds; during the summer, these respective numbers changed to 30%, 23% and 19%, with as much as 28% of the food in summer being crayfish (Cambarus ssp.).[17] Due to meeting the needs of their nestlings, eastern screech owls frequently consume less per day during summer than they do during winter. Five owls captured in April, averaging about 160 g (5.6 oz) in males and 190 g (6.7 oz) in females, gained on average 28 g (0.99 oz) when captured in fall (October–December) and 13 g (0.46 oz) when captured in winter (January–February).[14] In Michigan, screech owls consumed about 25% of their own weight per day during winter against 16% of their weight in summer. The average weight of vertebrate prey for screech owls in Michigan is 26 g (0.92 oz)[17] In Wisconsin, the average weight of vertebrate prey is 28 g (0.99 oz).[18] While much of their insect prey can weigh only a fraction of a gram, their largest prey, such as adult rats and pigeons and juvenile rabbits and gamebirds, can weigh up to at least 350 g (12 oz).[3]

Mortality[edit]

While eastern screech owls have lived for over 20 years in captivity, wild birds seldom, if ever live that long. Mortality rates of young and nestling owls may be as high as 70% (usually significantly less in adult screech owls). Many losses are due to predation. Common predators at screech owl nests including Virginia opossums (Didelphis virginiana), American minks (Neovison vison), weasels (Mustela ssp.), raccoons (Procyon lotor), ringtails (Bassariscus astutus), skunks, snakes, crows (Corvus ssp.), and blue jays.[3][7][19] Eastern fox squirrels (Sciurus niger) may raid the tree holes being used by eastern screech owls, not only destroying or consuming the eggs but also displacing the adult owls from the hole to use the hole from themselves.[17] Adults have fewer predators but larger species of owl do take them, since they have similar periods of activity. Larger owls known to have preyed on eastern screech owls have included great horned owls, barred owls (Strix varia), spotted owls (Strix occidentalis), long-eared owls (Asio otus), short-eared owls (Asio flammeus) and snowy owls (Bubo scandianus). Diurnal birds of prey may also kill and eat them including Cooper's hawks (Accipiter cooperii), northern harriers (Circus cyaenus), red-tailed hawks (Buteo jamaciensis), red-shouldered hawk (Buteo lineatus) and rough-legged hawks (Buteo lagopus).[3][16] Most prolific by far of the eastern screech owl's avian predators is the great horned owl, which can destroy up to 78% of a local population, but locally Cooper's hawks and barred owls can almost as serious of a threat.[17][20] A most dramatic case illustrating the owl food chain involved a barred owl, which up examination after being shot in New England contained a long-eared owl in its stomach that, in its own stomach, contained an eastern screech owl.[16] All other common owls in this species range also live off of similar rodent prey but direct competition is obviously disadvantageous to the screech owl. One exception is the even smaller northern saw-whet owl, on which eastern screech owls have been known to prey.[3] In rural Michigan, 9 different species of owl and diurnal raptor including the screech owl fed primarily on the same four species of small rodent from the Peromyscus and Microtus genera.[17] Eastern screech owls have had nesting attempts fail due to biocide poisoning, which causes the thinning of eggs and failure of nests, but seemingly not to the overall determent of the species. Collisions with cars, trains and windowpanes kill many screech owls, the earlier especially while feeding on road-side rodents and road-kills.[21][22]

Parasites[edit]

This species has the potential to be infected by several parasites including Plasmodium elongatum, Plasmodium forresteri and Plasmodium gundersi.

In popular culture[edit]

The 1992 comedy My Cousin Vinny starring Joe Pesci and Marisa Tomei has a scene with a screech owl. During the scene, the owl disturbs the main characters' sleep with its call. The bird's call is not realistically portrayed in the movie[citation needed]; the movie audio has the call as a loud, abrasive "screech" similar to that of a barn owl.

Image gallery[edit]

References[edit]

Notes[edit]

  1. ^ a b BirdLife International (2012). "Megascops asio". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ Sibley, David (2003). The Sibley Field Guide to Birds of Eastern North America. New York: Alfred A. Knopf. p. 225. ISBN 0-679-45120-X. 
  3. ^ a b c d e f g h i j k l m n o p q r s Voous, K.H. 1988. Owls of the Northern Hemisphere. The MIT Press, 0262220350.
  4. ^ "Eastern Screech Owl, Life History, All About Birds - Cornell Lab of Ornithology". Allaboutbirds.org. Retrieved 2012-08-31. 
  5. ^ Henny, C. J. and L. F. Van Camp. 1979. Annual weight cycle in wild screech owls. Auk 96:795-796.
  6. ^ Gehlbach, F. R. 1994. The Eastern Screech-Owl: life history, ecology, and behavior in suburbia and the countryside. Texas A&M Univ. Press, College Station.
  7. ^ a b c Gehlbach, Frederick R. 1995. Eastern Screech-Owl (Megascops asio), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology.
  8. ^ a b Marshall, Jr., J. T. 1967. Parallel variation in North and Middle American screech-owls. Monogr. West. Found. Vertebr. Zool. no. 1.
  9. ^ Bangs, O. 1930. The screech owls of eastern North America. Auk 47:403-404.
  10. ^ Ridgway, R. 1914. Otus asio [sensu stricto]. Pages 687-697 in Birds of North and Middle America, Pt. 6. Bull. U.S. Natl. Mus. no. 59.
  11. ^ a b Konig, C., Weick, F. & Becking, J-H. (2009). Owls of the World. Yale University Press, ISBN 0300142277.
  12. ^ a b Gehlbach, F. R. (1994). Nest-box versus natural-cavity nests of the eastern screech owl: an exploratory study. Journal of Raptor Research, 28, 154-157.
  13. ^ a b "Eastern Screech Owl Fact Sheet, Lincoln Park Zoo". Lpzoo.org. Retrieved 2012-08-31. 
  14. ^ a b c d e VanCamp, L. F., & Henny, C. J. (1975). The screech owl: its life history and population ecology in northern Ohio. North American Fauna, 1-65.
  15. ^ Murray, G. A. (1976). Geographic variation in the clutch sizes of seven owl species. The Auk, 602-613.
  16. ^ a b c Bent, A.C. (1938). Life histories of North American Birds of Prey, Vol. 2. Dover, New York.
  17. ^ a b c d e Craighead, J.J. & Craighead, F.C., Jr. 1956. Hawks, Owls and Wildlife. Stackpole, Washington DC, USA.
  18. ^ Jaksic, F. M. (1983). The trophic structure of sympatric assemblages of diurnal and nocturnal birds of prey. American Midland Naturalist, 152-162.
  19. ^ Smith, D. G., & Gilbert, R. (1981). Backpack radio transmitter attachment success in screech owls (Otus asio). North American Bird Bander, 6(4), 142-143.
  20. ^ Hegdal, P. L., & Colvin, B. A. (1988). Potential hazard to eastern screech‐owls and other raptors of brodifacoum bait used for vole control in orchards. Environmental toxicology and chemistry, 7(3), 245-260.
  21. ^ Loos, G., & Kerlinger, P. (1993). Road mortality of saw-whet and screech-owls on the Cape May peninsula. Journal of Raptor Research, 27(4), 210-213.
  22. ^ Thos. G. Scott. (1938). Wildlife mortality on Iowa highways. American Midland Naturalist, 527-539.

General references[edit]

  • Owlpages.com description of the eastern screech owl with a map of its range and recordings of its calls
  • USGS page for the eastern screech owl
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Names and Taxonomy

Taxonomy

Comments: Formerly treated as a subgenus within Otus (Marshall and King in Amadon and Bull 1988), but mitochondrial DNA and vocal differences with Old World species indicate that generic status is warranted (Konig et al. 1999).

Formerly considered conspecific with western O. kennicottii and Mexican and Middle American O. seductus and O. cooperi. Mixed pairs and overlap of Asio and kennicottii in se. Colorado and s. Texas attributed to long-distance dispersal in marginally poor habitat. Sympatry without interbreeding with kennicottii reported for w. Edwards Plateau (Dixon 1989).

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The currently accepted scientific name of eastern screech-owl is Megascops asio [41].
It is a member of the family Strigidae [27,41]. It was recently split from western screech-owl (M. kennicottii) which was formerly treated as a subspecies [3,21].
These two species interbreed in the Big Bend region of Texas, where their ranges overlap [21].

Marshall [21] accepted five subspecies:

M. a. maxwelliae (Ridgway), Rocky Mountain screech-owl
M. a. hasbroucki (Ridgway), Hasbrouck's screech-owl
M. a. mccalli (Cassin), Texas screech-owl
M. a. asio (Linneaus), southern screech-owl
M. a. floridanus (Ridgway), Florida screech-owl
  • 3. American Ornithologists' Union. 1983. Checklist of North American birds. 6th ed. Lawrence, KS: Allen Press, Inc. 877 p. [21234]
  • 21. Marshall, Joe T., Jr. 1967. Parallel variation in North and Middle American screech-owls. Monongraphs of the Western Foundation of Vertebrate Zoology No. 1. Los Angles, CA: Western Foundation of Vertebrate Zoology. 72 p. [24944]
  • 27. Sibley, Charles G.; Monroe, Burt L., Jr. 1990. Distribution and taxonomy of the birds of the world. New Haven, CT: Yale University Press. 1111 p. [22814]

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Common Names

eastern screech-owl
common screech-owl
shivering owl
little horned owl
little dukelet
demon owl
dusk owl

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Synonyms

Otus asio (Linnaeus)[27]
  • 27. Sibley, Charles G.; Monroe, Burt L., Jr. 1990. Distribution and taxonomy of the birds of the world. New Haven, CT: Yale University Press. 1111 p. [22814]

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