Spotted Owl - Declining Bird of Prey
A Near-Threatened Raptor of Western Old-growth Forests
Feb 20, 2009 Rosemary Drisdelle
Most North Americans have heard of the Spotted Owl, Strix occidentalis, if only because of the fierce battle waged by conservationists to save the bird. Though some concessions have been won, the species continues to dwindle and is listed on the IUCN Red List of Threatened Species as “Near Threatened.”
Spotted Owl Subspecies
Most authorities recognize three subspecies of Spotted Owl: the Mexican Spotted Owl in the Southwestern United States east of California, the Californian Spotted Owl in California, and the Northern Spotted Owl in the coastal mountains of British Columbia south to Northern California. All three are closely monitored and only the Californian subspecies is thought to have stable populations.
Why is the Spotted Owl Declining?
The two most significant threats to the Spotted Owl are habitat loss and competition from the Barred Owl:
- Habitat loss – the Spotted Owl nests in cavities or on ledges (the hollow tops of dead broken tree, holes in the sides of trees, small caves, on top of witch’s brooms such as those caused by mistletoe etc.) It perches high in the branches at night watching for prey such as wood rats, flying squirrels, and other small animals. Favored prey, like nesting sites, are typically abundant only in old-growth coniferous (evergreen) forests where dead trees remain standing and there is abundant and varied plant growth on the forest floor. Mature trees also provide high vantage points to perch while hunting, and cool shady places to sleep during the day.
- Barred Owls – the range of the Barred Owl, a similar species, has been expanding westward in the north and down the Pacific coastal mountain ranges. Where Spotted Owls have decreased, Barred Owls have taken over nesting sites and occasionally bred with Spotted Owls. Where Barred Owls have moved in, Spotted Owls don’t get the territory back.
Old-growth forest is continually being lost to logging, farming, development and other human land uses. Small separated patches of old-growth forest further stress Spotted Owl populations because these areas may not be large enough to provide enough food, and because juvenile birds, which leave the area they matured in to find a mate, must travel through dangerous open country to reach others of their kind. Eight out of ten die of starvation, are taken by predators, or are killed by accidents before they have a chance to breed.
More than two thirds of the old-growth forest formerly occupied by Spotted Owls has already been degraded. In Canada, once home to an estimated five hundred breeding pairs of Northern Spotted Owls, only about a dozen breeding pairs remain, and the species is likely to become extinct in the near future.
Spotted Owls are an Indicator Species
Too often, we consider a threatened species in isolation from all others, but Spotted Owls aren’t the only species that relies on old-growth forest: many other species of animals and plants face extinction if this unique ecosystem is lost. That’s why Spotted Owls are considered an indicator species—just one species representing a larger group that requires protection.
If North America’s old-growth forests are lost, it will take hundreds of years to get them back. Extinct species will be lost forever.
Read About Other Endangered Birds
Sources:
Firefly Encyclopedia of Birds. Perrins, Christopher ed. Buffalo: Firefly Books, 2003
“Spotted Owl Fact Sheet.” Western Canada Wilderness Committee
“Spotted Owls in Canada.” Cannings, Dick. BirdWatch Canada. Winter 2008: 8-10.
Spotted Owl
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Northern Spotted Owl
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