Eastern Screech Owl

Eastern Screech Owl
Eastern Screech Owl
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Strigiformes
Family:	Strigidae
Genus:	Megascops
Species:	M. asio
Binomial name
Megascops asio (Linnaeus, 1758)
Subespecies
See text.

The Eastern Screech Owl or Eastern Screech-Owl (Megascops asio) is a small owl that is relatively common in Eastern North America, from Mexico to Canada.^[1][2]

Description

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).^[3] 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 and broad-winged. They have a large round head with prominent ear tufts, yellow eyes and a yellowish bill. Rusty birds are more common in the southern parts of the range; pairings of the two color variants do occur. A pale gray variation also exists in western Canada and the north-central United States. The color variations are referred to as "red morph" and "gray morph" by bird watchers and ornithologists.

Breeding

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; they will also use nesting boxes. The bird doesn't actually build a nest; instead, females lay their eggs directly 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.^[4]

Eggs are laid every two days and incubation begins after laying of the first egg. The incubation period is about 26 days and the fledging period about 31 days. Females do most of the incubating but males will assist. The male provides most of the food while the female broods the young, and will stockpile food during early stages. Eastern Screech Owls are single brooded, but may re-nest if the first clutch is lost. When the young are small the female tears the food up for them.

Behavior

They 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. Though they generally go unnoticed, 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 a haunting tremolo with a descending, whinny-like quality.

Mortality

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 predatation. Common predators at screech owl nests including mink, weasels, raccoons, skunks, snakes, crows, and blue jays. 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, Long-eared Owls, Great Gray Owls, Short-eared Owls and Snowy Owls.

Habitat

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. These 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 behind loose boards on buildings, boxcars, or water tanks. They will also roost in dense foliage of trees, usually on a branch next to the trunk, or in dense scrubby brush.

Feeding habits

Like most predators, Eastern Screech-Owls are opportunistic hunters. They 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, occasionally hovering 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 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.^[4]

For the better part of the year, 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. Also taken are crayfish, snails, spiders, earthworms, scorpions, and centipedes. Small mammals, ranging in size from shrews to rabbits, are regular prey and often become the owl's primary prey 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 are also taken. Small birds such as chickadees, 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. However, much larger avian prey is sometimes caught, including rock pigeons, northern bobwhite and even ruffed grouse (which are heavier than the screech owls). Irregularly, small fish, small snakes, lizards, baby soft-shelled turtles, small frogs, toads, 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.

Parasites

This species is infected by several parasites including Plasmodium elongatum, Plasmodium forresteri and Plasmodium gundersi.

Subspecies

There are 5 recognized subspecies:^[5]

• Megascops asio asio (Linnaeus, 1758)
• Megascops asio floridanus (Ridgway, 1874)
• Megascops asio hasbroucki (Ridgway, 1914)
• Megascops asio maxwelliae (Ridgway, 1877)
• Megascops asio mccallii (Cassin, 1854)

In popular culture

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; the movie audio has the call as a loud, abrasive "screech".

Image gallery

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  Gray morph

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  Gray morph

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  Red morph

• 

  Gray morph (left) and red morph (right)

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  Red morph

• 

  Red morph

References

Notes

1. ^ ^{a b} "Megascops asio". IUCN Red List of Threatened Species. Version 2010.4. International Union for Conservation of Nature. 2009. http://www.iucnredlist.org/apps/redlist/details/143201. Retrieved 4 April 2011. 
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. ^ http://www.allaboutbirds.org/guide/Eastern_Screech-Owl/lifehistory
4. ^ ^{a b} "Eastern Screech Owl Fact Sheet, Lincoln Park Zoo"
5. ^ "Megascops asio". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=686658. Retrieved 05 April 2011. 

General references

• BirdLife International (2004). Megascops asio. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006.
• 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

External links

• Eastern Screech Owl - Otus asio - USGS Patuxent Bird Identification InfoCenter
• Eastern Screech Owl Species Account - Cornell Lab of Ornithology
• Eastern Screech Owl - eNature.com
• Eastern Screech Owl Information and Photos - South Dakota Birds and Birding
• Eastern Screech Owl videos, photos & sounds on the Internet Bird Collection
• Dewey, Tanya, and Stephen McDonald (2006). "Otus asio". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/otus_asio.html. 
• Eastern Screech-Owl - The Peregrine Fund
• Eastern Screech-Owl - Megascops (Otus) asio
• Eastern Screech-Owl Bird Sound

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