Northern Spotted Owl – Strix occidentalis caurina

 Taxonomy

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A northern spotted owl losing its habitat

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 Name

• Scientific name: Strix occidentalis caurina.
• Common name: Northern spotted owl.

Habitat and Distribution

• The northern spotted owl is one of the three species of spotted owls, the other two are the California and the Mexican spotted owls.
• Northern spotted owls have historically inhabited forests throughout southwestern British Columbia in Canada, western Washington, western Oregon and northwest California.
• According to Oregon Fish and Wildlife Office suitable land has been reduced by 60% over the last 190 years.
• They inhabit old growth coniferous forest with large trees and layers of branches.

Physical Features

• They have large rounded head with no visible ear tufts. Feathers in the head are dark brown  with small white irregular specked spots and dark feathers surrounding their eyes.
• The body is dark brown with white round spots.
• They can be differentiated from the barried owl by its darker feathers and its smaller size.
• Females are larger than males.
• Northern spotted owls have dark colored eyes. Most owls have yellow or orange eyes.

Size and length

• Its length ranges from 16.5 to 19 inches or 42 to 48 centimeters.
• Males weigh 21 oz while females 23 oz.
• Its wingspan is 40 to 50 inches or 101 to 127 centimeters,

Behavior

• Northern spotted owls are nocturnal predators. They sit on branches at night and use their sight to find prey. They silently attack their prey from above.
• They are non migratory birds unless there is a drastic change in its ecosystem.
• These owls are very territorial and need large open space for hunting and nesting.
• They are monogamous and mate for life.
• Northern spotted owls produce sounds to communicate including grunts, groans, hoots and chatters. The most common call is a high pitch “whooo-hu-ho”

Diet

• Northern spotted owls are carnivores. Their diet consists in small rodents, flying squirrels, wood rats and birds.
• They swallow their prey whole. Their pellets contain undigested parts of their prey such as feathers and bones.

Reproduction

• Mating season varies with geographical location. They generally mate from February to March.
• They reach reproductive maturity at 3 years old.
• They lay 1 to 4 eggs and incubation lasts 30 days. During the incubation period the male brings food to the female.
• Northern spotted owls do not build their own nests instead they use abandoned nests of ravens or raptors in the tops of trees or cavities of diseased trees.

The Young

• After hatching the young stay with their mothers for 10 days while the male brings food.
• They stay with their parents for one month after which they find their own food and territory.
• Their feathers are lighter brown.

 Life Expectancy

• They live up to 20 years in captivity and 10 years in the wild.

Threats

• Overharvesting of habitat, land conversions and forest fires.
• According to Oregon Fish and Wildlife Office Population is decreasing at an average rate of 2.9% each year.
• The habitat of the barrel owl, a larger and more aggressive owl, overlaps the range of the northern spotted owl competing for habitat and prey. They usually prey on young northern spotted owls.

Conservation Status

• It is considered a threatened species under the Endangered Species Act.
• The IUCN Red List of Threatened Species has not yet assessed the species.

References and further research

Washington Forest Protection Association

Oregon Fish and Wildlife Office

National Park Service – Muir Woods

Smithsonian Magazine

National Wildlife Federation