Spotted Owl caurina subspecies
Scientific Name: Strix occidentalis caurina
Other/Previous Names: Northern Spotted Owl,Spotted Owl,Strix occidentalis
Taxonomy Group: Birds
Range: British Columbia
Last COSEWIC Assessment: April 2008
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered
Quick Links: | Taxonomy | Photo | Description | Distribution and Population | Habitat | Biology | Threats | Protection | Other Protection or Status | Recovery Initiatives | National Recovery Program | Documents
Image of Spotted Owl caurina subspecies
There are currently three recognized subspecies of the Spotted Owl: the Northern Spotted Owl, the California spotted owl and the Mexican spotted owl. Only the Northern Spotted Owl (Strix occidentalis caurina) is found in Canada.
The caurina subspecies of the Spotted Owl is a medium-sized owl. It measures 45 cm in length and has a wingspan of about 90 cm. The plumage is dark overall; the dark brown feathers are speckled with small, roundish pale spots over most of the body and white horizontal bars on the tail. The Spotted Owl has a round head with no ear tufts. The large, dark brown eyes are set in a light brown facial disk (a ring of feathers surrounding the face). After five months, juvenile owls moult their downy feathers and begin to resemble adults. Females are slightly larger than males but have similar plumage.
Distribution and Population
The Spotted Owl is found in North America, from southwestern British Columbia to Mexico. The range of the caurina subspecies of the Spotted Owl extends from the southwestern mainland of British Columbia through western Washington, western Oregon, and the coastal ranges of northern California. In Canada, the caurina subspecies is thinly distributed across an area of British Columbia bounded by the border with the United States to the south, Carpenter Lake to the north, Howe Sound to the west, and Lillooet and eastern E.C. Manning Provincial Park to the east, just beyond the height of land of the Cascade Mountains. Prior to European settlement the total Canadian population is estimated to have been 500 pairs, which fell to fewer than 100 pairs in 1991 and fewer than 30 pairs in 2002. Recent inventories found 17 sites with a total of 25 individuals in 2004, 17 sites with a total of 24 individuals in 2005, 14 sites with a total of 17 individuals in 2006, and 14 sites with a total of 19 individuals, only 10 of which were in breeding pairs, in 2007. All of the adults surveyed were old and near the end of their breeding age. Without increased habitat protection and direct augmentation of the population, the caurina subspecies of the Spotted Owl cannot avoid being extirpated; if present trends continue, extirpation will occur by 2012.
The caurina subspecies of the Spotted Owl is found in uneven-aged coniferous forests characterized by a multi-layered canopy that includes numerous large trees with broken tops, deformed limbs and large cavities, many large snags, and major accumulations of logs and woody debris on the ground. The caurina subspecies of the Spotted Owl typically nests in various species of old-growth trees and does not build its own nest, preferring naturally occurring nesting sites such as broken large-diameter trunks, cavities in large trees, or old stick (platform) nests of other bird species. A wider range of habitats is required for foraging than for nesting or resting. The caurina subspecies of the Spotted Owl appears to select sheltered roosts to avoid poor weather, summer heat or predators. It has a narrow preferred temperature range. The amount of suitable habitat for the caurina subspecies of the Spotted Owl has decreased since European settlement and is expected to continue to decrease until 2030. Most sites currently occupied by the caurina subspecies of the Spotted Owl are in protected areas or are protected by special government orders, but authorized logging continues in some active sites.
The caurina subspecies of the Spotted Owl typically begins breeding at two or three years of age. Spotted Owls begin roosting in pairs near the nest in late winter and early spring, with mating generally occurring two to three weeks before nesting. Spotted Owls typically stay with the same partner their entire life and the caurina subspecies of the Spotted Owl does not migrate. Spotted Owls do not breed every year; the same nest is reused each year. Females lay one or two eggs, which they incubate alone, and then brood the chicks while the males provide food for the whole family. In British Columbia, juveniles fledge between June 9 and 26. They remain near the nest through August and late September before dispersing. Juvenile mortality during dispersal is very high. With its acute eyesight, acute hearing and feathers modified for silent flight, the Spotted Owl is well adapted to nocturnal predation. In British Columbia, the northern flying squirrel, the bushy-tailed wood rat and the deer mouse are the preferred prey. The caurina subspecies of the Spotted Owl is long-lived; some individuals in the wild are more than 17 years old.
The caurina subspecies of the Spotted Owl is highly vulnerable in British Columbia because of its small population size and low density. Recruitment of young owls into the Canadian population seems to have ceased, since no juvenile owls are reaching adulthood. If no natural recruitment is occurring, the population is probably doomed to extirpation by 2012. Continued habitat degradation caused by logging and development is one of the primary threats to the caurina subspecies in Canada. Logging affects Spotted Owls by modifying the structure and composition of the forests, isolating breeding pairs, and fragmenting forest habitat into patches that are so small that they become unsuitable. Because the food supply available to these birds is dependent on the type, structure and composition of the forest, forest management practices have an important effect on prey populations and consequently on owl densities. If logged areas are managed in accordance with the habitat needs of the Spotted Owl, habitat loss from logging could be less permanent than losses associated with urban and rural development. Habitat loss to urban and agricultural development is undoubtedly permanent. Competition with the closely related barred owl, which is relatively common throughout the habitat of the caurina subspecies of the Spotted Owl in British Columbia, poses another threat. The barred owl competes with the Spotted Owl for space and prey; as well, the barred owl is a predator of the Spotted Owl and the two owl species can hybridize. Unlike the caurina subspecies of the Spotted Owl, the barred owl is able to thrive in a variety of forest types and can adapt to more varied food sources; as a result, it likely has a competitive advantage in fragmented old-growth forests. Any displacement by barred owls of the caurina subspecies of the Spotted Owl would have serious consequences for the very small population in Canada. Increased predation by raptors that prefer more fragmented forests is another major threat. Predation by the great horned owl accounts for a large proportion of juvenile mortality.
Federal ProtectionThe Spotted Owl caurina subspecies is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
The caurina subspecies of the Spotted Owl is protected under the British Columbia Wildlife Act, which prohibits harming birds, their nests or their eggs. The habitat can also be protected through the Identified Wildlife Management Strategy under the Forest and Range Practices Act and as part of Old Growth Management Areas. Most of the active sites are in provincial parks or other protected areas and are therefore protected.
Provincial and Territorial Protection
Other Protection or Status
The Spotted Owl is listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which regulates international trade in species that are or may become threatened by commercial trade.
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Northern Spotted Owl (Strix occidentalis caurina) in British Columbia
Status Final posting on SAR registry
Recovery Progress and Activities
Summary of Progress to Date The Northern Spotted Owl was designated as endangered by COSEWIC in 1986 and was red-listed by the BC Conservation Data Centre in 1989. The province adopted a Spotted Owl Management Plan in 1997 that set aside 363,000 hectares to be managed for Spotted Owls. The Spotted Owl Management Plan covers two of the three forest districts in the range of the Spotted Owl in BC (Squamish and Chilliwack). In response to the 2002 population estimate, two major forestry companies (Interfor and Canfor) voluntarily deferred harvesting in Spotted Owl habitat in these districts until new management guidelines had been developed. In the third district (Merritt) the main logging company working in Spotted Owl habitat (Ainsworth) has agreed to protect Spotted Owl habitat to the standards of the Spotted Owl Management Plan. A Spotted Owl Recovery Team was established in 2002. It has drafted a Recovery Strategy and is working on related Recovery Action Plans with a major effort being put into a habitat/population model to help understand the relationship between the biological and habitat dimensions of recovery. Completion of the Recovery Strategy and Action Plans will enable the BC government to re-evaluate the Spotted Owl Management Plan in the context of new science and analysis and in accordance with current forest and wildlife management legislation. As part of this process, the provincial government is undertaking a parallel analysis of the socio-economic costs and benefits associated with Spotted Owl recovery in BC. Summary of Research/Monitoring Activities Between 1990 and 2002, Spotted Owls were monitored annually in British Columbia, providing population estimates and increasing the understanding of the owl’s habitat requirements. In 1991, the provincial population was estimated at less than 100 pairs. By 2001, the estimate had declined to fewer than 50 breeding pairs and owl numbers were declining at a greater rate than the management plan predicted (average annual decline of 7%). In 2002, this estimate was revised to 33 pairs and a 10% annual decline rate. Further analysis of the survey data has shown that the upper elevation limit of suitable old-growth forest habitat used by breeding Spotted Owls in BC is lower than previously thought. Recent surveys have focused on confirming owl activity at previously used sites and locating new sites in areas with highly suitable habitat. The Spotted Owl Recovery Team is currently working on a habitat/population model that is assisting to identify and map suitable habitat. In January 2004, a two-day Northern Spotted Owl modeling workshop provided a forum for collaboration by scientists, stakeholders and decision makers. The proceedings of this workshop are available on-line (www.forrex.org/publications/forrexseries/fs14.pdf). A follow-up meeting occurred in March 2005. Summary of Recovery Activities The Spotted Owl Management Plan of 1997 was designed to mitigate the impacts of logging by identifying 3200 ha management areas around known and potential Spotted Owl territories. The objective was to maintain approximately 67% of each territory as suitable habitat. The 67% target would be achieved by a variety of means, including retention of some old-growth forests, logging in younger forests and enhancement of potential Spotted Owl habitat through silvicultural practices such as thinning. As a result of the plan, harvest levels within identified territories have been reduced to almost negligible levels. However, reduction of harvesting within identified territories has resulted in increased harvesting in adjacent areas. Fragmentation of habitat, which increases the owls’ risk of predation while traveling between suitable habitat patches continues to be a major challenge to recovery. An additional major threat which is only just beginning to be better understood is increased competition from the larger, more aggressive Barred Owl, whose range is expanding into that of the Spotted Owl. Spotted Owls in BC face extremely high mortality in their first winter. The movements of juvenile owls have been tracked by radio telemetry to determine their activity patterns, survival and recruitment rates, and causes of death. As part of this work, the birds are fed mice when they are encountered which has led to consideration of supplemental feeding of juveniles as a potential recovery activity. Two of the three chicks tagged with a radio transmitter in 2003 survived the winter. Of three young tagged in 2004, one is still surviving, one was killed by a Great Horned Owl and the third died of starvation.
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
7 record(s) found.
- COSEWIC Status Reports (2 record(s) found.)
- COSEWIC Assessments (2 record(s) found.)
- Response Statements (1 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
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