Barred owl

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Barred owl
Barred owl

Barred owl

Systematics
Class : Birds (aves)
Order : Owls (Strigiformes)
Family : Real owls (Strigidae)
Genre : Strix
Type : Barred owl
Scientific name
Strix varia
Barton , 1799

The barred owl ( Strix varia ) is a large species of owl from the family of real owls (Strigidae). The strongly fragmented distribution area includes large parts of North America from southeast Alaska to the east to Nova Scotia and south to Florida and to the southern tip of Mexico . The animals inhabit old coniferous and mixed forests , but also more open wooded landscapes, forests thinned by timber removal and locally also larger parks with old trees. The diet consists mainly of small mammals, barnacles also eat birds, other small vertebrates and invertebrates . The world population and the range are very large and the population has increased significantly in the last 40 years, the IUCN therefore classifies the species as non-endangered (“least concern”).

description

Barred owls are large owls with a large, round head and toes that are feathered up to their claws, but the toe feathering is reduced or bristle-like in the southern subspecies. As with all species of the genus Strix , feather ears are missing . The body length is 48–55 cm. As with most owls, the sexes do not differ in terms of coloration, but females are on average significantly larger and heavier than males. Males of the nominate form S. varia varia have a wing length of 312-340 mm and a weight of 468-774 g, females have a wing length of 330-352 mm and a weight of 610-1051 g.

In adult birds of the nominate form, the skull, the entire upper side of the trunk and the upper wing-coverts are brown to gray-brown. On this basis, the upper head and back show a whitish transverse banding and the upper wing-coverts show whitish spots. The wings are banded whitish beige and brown, the control feathers are brown or gray-brown with four or five whitish bands. The underside is pale gray-brown or dirty white. The front neck and the upper chest show a dense, dark banding, the rest of the underside a strong dark brown to reddish brown dotted line.

The coloring is not very contrasty on the head either. The pale gray-brown face veil shows fine, dark, concentric rings and is only indistinctly set off from the rest of the head plumage, the area around the eyes is not darker than the rest of the face veil. The sides of the head and neck are banded in light dark. The beak is light yellowish with a faint shade of green. The claws are dark horn-colored with blackish tips. The iris is dark brown to blackish brown.

The youth dress does not differ from the adult dress.

Barred owl of the nominate form ( S. v. Varia ) in the area of ​​the north-eastern distribution limit in Québec .

Vocalizations

The males have two different courtship and territory chants. One chant consists of a series of deep, barking and throaty calls that increase in volume and ends with an explosive, higher, two-syllable sound with the emphasis on the second syllable, something like "ok-ok-ok-ok-ok-ok -buhóoh " . The second chant is a rhythmic "whohú-buhóoh whohú-buhóoh" , in English onomatopoeic with the phrase "I cook today - you cook tomorrow" . Both stanzas are repeated a few seconds apart. König and Weick suspect that the two chants reflect different “moods” of the male and that the second chant is uttered when the male is more excited.

distribution and habitat

The strongly fragmented distribution area includes large parts of North America from southeast Alaska to the east to Nova Scotia and south to Florida and to the southern tip of Mexico . The animals inhabit old coniferous and mixed forests , but also more open wooded landscapes, forests thinned by timber removal and locally also larger parks with old trees.

The world population is very large. It was estimated at around 600,000 sexually mature individuals in 2009 and has increased by around 87 percent over the past 40 years. The IUCN therefore classifies the species as " least concern ".

Since the barred owl is displacing the spotted owl in some regions of the USA , the US Fish and Wildlife Service announced in the summer of 2013 that more than 3,600 barred owls would be shot in the US states of California, Oregon and Washington over the next four years. It will then be observed whether the spotted owl populations in these areas recover.

nutrition

The food mainly consists of small mammals up to the size of young hares , barnacles also eat birds, other small vertebrates and invertebrates . The birds usually hunt from a stand guard and watch the ground, the prey is then flown to and grabbed on the ground. Similar to the tawny owl, barred owls also scare away birds sitting in bushes by flapping their wings and catching them. The animals can also catch bats in flight and prey on fish by wading in shallow water.

Barred owl in the branching stage

Reproduction

Barred owls live in pairs in territories that are defended against conspecifics by both pair partners. Tree cavities in the interior of the forest are mostly used for breeding, but also larger free nests of birds of prey and other large birds and, rarely, goblins of squirrels . In the south of the distribution area broods in the crowns of palmetto palms ( Sabal palmetto ), in palm stumps and, exceptionally , also broods in the ground have been documented. The eggs are laid between January and June. The clutch usually consists of 2 to 3, maximum 5 eggs, which are only incubated by the female for 28 to 33 days. The nestlings are also tucked and fed exclusively by the female, during this time the male provides the female and then also the nestlings with food. The young birds reach the branching stage at around 42 days of age and can then leave the nest and climb onto neighboring branches. They are then guarded and fed with food by both parents for several weeks. In favorable years, second and even third broods are possible.

Systematics

Four subspecies are recognized:

  • Strix varia Barton , 1799 - Largest part of the range, from southeast Alaska east to Nova Scotia and in the east of the USA south to north Texas and North Carolina . The nominate form is described above.
  • Strix varia georgica Latham 1802 - Southeastern United States from southern North Carolina to Georgia and Florida . Overall lighter than the nominate shape, but the base color is more beige on the top and more ocher on the underside. Slightly smaller than the nominate shape and toe fletching rather bristly.
  • Strix varia helveola ( Bangs 1899) - Texas and adjacent lowlands in Mexico. Basic color pale red-brown, toe fletching largely reduced or somewhat bristly.
  • Strix varia sartorii ( Ridgway 1873) - Montane areas in central and southern Mexico at altitudes between 1500 and 2500 m. Darkest subspecies, toe fletching largely reduced.

swell

Individual evidence

  1. ^ A b Claus König, Friedhelm Weick: Owls of the World . Christopher Helm, London 2008, ISBN 978-0-7136-6548-2 : p. 379
  2. ↑ Claus König, Friedhelm Weick: Owls of the World . Christopher Helm, London 2008, ISBN 978-0-7136-6548-2 : p. 378
  3. ↑ BirdLife International (2011) Species factsheet: Strix varia . ( Online , accessed November 19, 2011)
  4. ↑ US Fish and Wildlife Service of July 23, 2013: Encroaching Competitor Adds to Spotted Owl's Struggle.
    seattletimes.com from July 23, 2013: Feds plan to shoot barred owls.

literature

Web links

Other web links

Commons : Barred Owl  - Album with pictures, videos and audio files