Western screech-owl

Western screech-owl
Scientific classification
Kingdom Information
Domain	Eukaryota
Kingdom	Animalia
Subkingdom	Bilateria
Branch	Deuterostomia
Phylum Information
Phylum	Chordata
Sub-phylum	Vertebrata
Infraphylum	Gnathostomata
Class Information
Superclass	Tetrapoda
Class	Aves
Sub-class	Neornithes
Infra-class	Neoaves
Order Information
Order	Strigiformes
Family Information
Families	Strigidae
Sub-family	Striginae
Genus Information
Genus	Megascops
Species Information
Species	M. kennicottii
Population statistics
Population	400,000 (2015 est.)
Conservation status	Least concern

The western screech owl (Megascops kennicottii) is a species of owl of the family Strigidae, and found throughout much of western North America.

Description

The western screech owl is medium-sized, with a body length of 8.7 inches, a wingspan of 22 inches, and weigh 3.1-7.8 ounces. Females are slightly larger than males. The owl is predominantly gray in color. It has short, tapered ear tufts and a drab-gray facial disk around yellow eyes. The underside of the body is slightly lighter than the top and has dark, wide longitudinal stripes and thin horizontal banding. The legs are feathered to the toes. The beak is blackish. An uncommon brown morph is found in the Pacific northwest.

Until the 1980s this species and the eastern screech owl (Megascops asio) were considered to be one species due to similarities in appearance. Slight differences in coloration - most apparently the lack of a red morph - in addition to differing calls (a "bouncing ball" series of calls), led researchers to classify the western screech owl as a distinct species.

Subspecies

• Megascops kennicottii aikeni; southern California to western Oklahoma, south to Mexico (Sonora).
• Megascops kennicottii bendirei; south central Oregon to northern Baja California.
• Megascops kennicottii cardonensis; southern California to northern Baja California.
• Megascops kennicottii kennicottii; coastal southern Alaska to northwestern Canada, south to northwestern California.
• Megascops kennicottii macfarlanei; southeastern British Columbia to northeastern California, east to Wyoming.
• Megascops kennicottii suttoni; southwestern Texas to Mexican plateau.
• Megascops kennicottii vinaceus; Mexico: southern Sonora and western Chihuahua to northern Sinaloa.
• Megascops kennicottii xantusi; southern Baja California (Cape district).
• Megascops kennicottii yumanensis; southeastern California and southwestern Arizona to Mexico (northwestern Sonora).

Range and habitat

The range of ​​the western screech owl runs west of the Rocky Mountains from northern Canada and Alaska to central Mexico. The eastern range limit is not completely clear, but there is a possibility it overlaps with that of the eastern screech owl. In northern areas of its range they migrate further south during the winter months; however, the majority of western screech owls within their range are resident birds.

Their habitat is arid to semi-humid forested areas, from pine-oak forests to semi-open wooded areas, and forest edges. It also occurs in regions that have only a loose tree population and inhabits semi-deserts with mesquite and large cacti. It has also taken advantage of human-altered areas, becoming residents within buildings and suburban gardens and parks.

Diet

The western screech owl is a nocturnal owl species, usually becoming active twenty to thirty minutes after sunset. Their food is predominantly large insects, but also small vertebrates such as mammals, birds, frogs and reptiles, with the occasional kill exceeding the size of the owl, up to the size of cottontail rabbits. In winter small mammals are a major part of the diet, and will create food depots.

Reproduction

The breeding season begins in late February, when the males begin singing at dusk. Nests which are chosen are usually the former tree holes of woodpeckers. The clutch consists of three to seven eggs, with the female alone incubating the clutch until hatching about 26 days later. They leave the nest around the age of four weeks, but are cared for by the parent birds for another five to six weeks. Both parents are defensive of the nest, attacking intruders if they get too close.

Threats

The secretive nature of the western screech owl has made it difficult to assess the overall health and population of the bird. The North American Breeding Bird Survey has reported a decline in numbers between 1966-2015, but it has admitted that its sample sizes were not large enough to get a good estimation; one government 2012 study within the Six Rivers National Forest of northern California could only manage to detect six individual owls, not due to scarcity but to the owls own habits.

Still, the assumption is that the bird is declining in numbers, with a combination of human activities removing a large number of old-growth trees required for nesting, as well as predation from the barred owl (Strix varia) and great horned owl (Bubo virginianus); both owls have been blamed for the local absence of the western screech owl on southern Vancouver Island in British Columbia.