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NORTHERN SPOTTED OWL (Strix occidentalis caurina)

10. Knowledge Gaps

A draft list of research topics (see Appendix 2) has been prepared by members of the SORT. These topics include research on demography, population trends, population modeling, genetics, competition, habitat maintenance, habitat enhancement, and relationships with prey. The SORT needs to set priorities for research topics based on the urgency of the need for information for recovery purposes. Challenges associated with implementing these research programs for Spotted Owls are referenced in section 9.


10.1 Habitat Requirements

Very little habitat research has been conducted to-date for Spotted Owls in British Columbia. Research conducted in the United States has been used as a surrogate. Although this is likely a legitimate exercise, especially using data from Washington where habitats are most similar, the complete applicability to British Columbia can always be questioned.

It would be useful to acquire local data to better define nesting, roosting, and dispersal habitat in the province, and to define how they relate to recovery planning. Some of this work is necessary to enable us to effectively define survival, recovery, and critical habitats, and to better understand how fragmentation affects the quality of these habitats for Spotted Owls. It will be important to model this information on both spatial and temporal scales to plan for the owl’s recovery needs.


10.2 Inventory Requirements

In British Columbia, known Spotted Owl locations have been surveyed relatively intensively during the last 10 years. From 1992 to 2002, more than 150 potential locations thought to be capable of supporting owls were surveyed with various intensities to assess the current range, distribution, and abundance of Spotted Owls. Spotted Owls have been detected at 65 locations in the province, 40 of which were used to assess the population trend since 1992 (Blackburn et al. 2002). Most of the survey effort was performed in the mid 1990s, and most locations have not been revisited for 5 years or more. Other potential habitats remain unsurveyed in the province.

Further inventory effort for Spotted Owls is deemed the highest priority among recovery actions. A comprehensive inventory program is needed to find and confirm the current population estimate of 33 breeding pairs, to determine the full extent of their range, to assess the population’s reproductive potential, and to support potential augmentation efforts. Only 15 of the 64 known locations (Table 1) are currently known to be active. Breeding status is unknown for most of them.


10.3 Biological / Ecological Research Requirements

Relatively little research has been conducted on the ecology of Spotted Owls in British Columbia. Most background information reported is from studies conducted in the United States. Of particular immediate importance is to conduct further research on the main prey species, the Northern Flying Squirrel, because early efforts by Ransome and Sullivan (2003) suggest a possible decline in flying squirrel numbers in some Vancouver watersheds that appears to coincide with declines in both Spotted and Barred owls (Blackburn et al. 2002).