Northern spotted owl (Strix occidentalis caurina) recovery strategy: chapter 3
The Northern Spotted Owl (Strix occidentalis caurina) is among the most studied, high profiled owl species in the world because of its close association with old forests and the use of these forests by society for urbanization and resource extraction. In Canada, the Spotted Owl was designated Endangered in 1986 (renewed in 2000) by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
The Spotted Owl occurs in the Pacific Northwest region of North America. In Canada, it occurs only in the southwest mainland of British Columbia, accounting for about 8% of its global range. Spotted Owl populations throughout the Pacific Northwest are declining. In British Columbia, the number of Spotted Owls declined between 1992 and 2002 by as much as 67%, at an annual rate of 10.4%. The current Canadian population is estimated to be less than 33 breeding pairs, which is about 0.5–1% of the estimated global population. Small populations are highly vulnerable to extinction, and it is thought that the Spotted Owl population in British Columbia may become extirpated within a few years.
Spotted Owls in British Columbia are limited by diminished quantity and quality of habitat, reduced connectivity of habitat, and increased isolation from the larger population in the United States. Threats include further loss and fragmentation of habitat, competition and hybridization with Barred Owls, predation by Great Horned Owls and other predators, climate change, negative effects from environmental and genetic variables, and disease (e.g., West Nile virus). Combined, these factors influence the survival, reproductive, recruitment, and immigration rates of the species.
Challenges to recovery in Canada include the precipitous rate of population decline, isolation from larger populations to the south in the United States, and the high risk that the current small, sparsely distributed population will continue to decline and soon become extirpated. Other challenges include balancing society’s needs for both economic opportunity and recovery of endangered species, the long time frame required to restore habitats and connectivity, and the high financial costs of monitoring, research, habitat restoration, and population augmentation efforts. Some threats pose challenges that may not be manageable, such as competition from Barred Owls, severe environmental events, and potential mortality from West Nile virus.
Despite all of these challenges, recovery of the Spotted Owl in British Columbia is biologically feasible. Habitat is currently available to support owls and opportunities exist to improve future habitat conditions. Recovery is not constrained by land ownership, and thus forested areas additional to those currently being managed for Spotted Owls are available, if needed, to increase the recovery potential of the owl population. Opportunities also exist to augment the population to increase recruitment rates.
The recovery goal is to down-list the Spotted Owl from its current Endangered status by establishing a stable or increasing, self-sustaining population that is distributed throughout the species’ natural range. The long-term population goal is to increase the number of owls to at least 250 adult owls, so that the species meets the minimum COSEWIC population size requirement for down-listing from Endangered to Threatened.
Recovery objectives are to (1) stop the population decline to prevent extirpation, (2) increase the number of Spotted Owls to maintain a stable, self-sustaining population throughout its range, and (3) conserve and restore sufficient habitat throughout the species’ range to support a self-sustaining population of Spotted Owls.
Strategies to stop the population decline include the immediate protection of all Spotted Owls and the habitat they occupy, and the conservation of sufficient survival habitat to maintain the current population.
Strategies to increase the owl population include population assessment, population augmentation (e.g., captive breeding, captive overwintering of juveniles, and translocation of solitary wild owls to territories with a potential mate), and other possible management actions to artificially increase survivorship and fecundity (e.g., supplementation of prey populations and removal of competitors).
Strategies to conserve and restore owl habitat include habitat supply modeling, identification and conservation of critical habitats (survival and recovery habitats), and development of habitat management guidelines to create, enhance, and maintain habitat.
Strategies to support recovery actions include promoting habitat and owl population stewardship, providing financial resource assistance, adaptive management and research, public awareness, and innovative solutions to address social and economic consequences.
Continued population inventory and monitoring is recognized as the highest priority recovery action on which all other aspects of recovery actions will be based. Comprehensive inventory followed by regular monitoring is needed to better understand the full distribution of the Spotted Owl in British Columbia, to identify critical habitats, to get more rigorous estimates of abundance and trend, and to identify sites where birds could be taken from for augmentation measures. Simply relying on past inventory data to develop recovery actions may negate the likelihood of recovering the population.
Recovery actions already underway include implementation of the Spotted Owl Management Plan, various analyses of the success of that plan, re-establishment of the Spotted Owl Recovery Team, preparation of an updated status report, limited ongoing inventory, new habitat and population modeling, experimental capture and release of a juvenile owl, voluntary deferment of logging by some forest companies, and development of conservation tools (e.g., Identified Wildlife Management Strategy) under the Forest Practices Code and Forest and Range Practices Act.
Evaluation criteria for the recovery strategy include several performance measures, such as prevention of extirpation, conservation of sufficient habitat to maintain a viable population, and preparation of various recovery action plans.
Unless specified, the term “Spotted Owl” in this document refers to the Northern Spotted Owl.
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