BC Conservation Data Centre: Conservation Status Report
Sphyrapicus thyroideus
Williamson's Sapsucker
| Scientific Name: | Sphyrapicus thyroideus |
|---|---|
| English Name: | Williamson's Sapsucker |
| Provincial Status Summary | |
| Status: | S3B |
| Date Status Assigned: | January 02, 2013 |
| Date Last Reviewed: | March 25, 2022 |
| Reasons: | Williamson's Sapsucker has limited range and sparse distribution in BC. Threats to habitat are primarily from forest harvesting. |
| Range | |
| Range Extent: | F = 20,000-200,000 square km |
| Range Extent Estimate (km2): | 69,187 km2 (COSEWIC 2017e) |
| Range Extent Comments: | The Williamson's Sapsucker breeds in three separate areas in southern British Columbia: the northern Cascade Mountains; the plateau connecting the Okanagan and Boundary regions in the Southern Interior Ecoprovince; and the southern Purcell Mountains in the Southern Interior Mountains Ecoprovince (Chytyk and Fraser 2015). The breeding range has expanded since The Birds of British Columbia was published in 1990, due to a combination of greater search effort from provincial surveys and Breeding Bird Atlas work, and a true range expansion in both the Kootenay and Thompson-Okanagan regions (Chytyk and Fraser 2015). The species is now found further to the west and north along the Fraser and Thompson Rivers (COSEWIC 2017e, Gyug et al. 2020), and the East Kootenay population that was thought to have been extirpated (Campbell et al.1990b) actually hung on as a very rare breeder (Gyug et al. 2020). |
| Area of Occupancy (km2): | G = 501-2,500 |
| Area of Occupancy Estimate (km2): | 418 4 square km grid cells (COSEWIC 2017e) |
| Area of Occupancy Comments: | 418 occupied grid squares documented in COSEWIC (2017e). Undoubtedly more to be found (D. Fraser, pers. comm. 2020). |
| Occurrences & Population | |
| Number of Occurrences: | DE = 81 to >300 |
| Comments: | Relatively restricted distribution in B.C. Sparsely distributed at middle to higher elevations in southern interior. Appears to have recolonized the Kootenays as larch forests recover from historic logging (D. Fraser, pers. comm. 2020). |
| Number of Occurrences with Good Viability / Ecological Integrity: | Rank Factor not assessed |
| Number of Occurrences Appropriately Protected & Managed: | Rank Factor not assessed |
| Population Size: | CD = 250 - 2,500 individuals |
| Comments: | 960 (520-1440) is the population estimate in COSEWIC (2017e) |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | B = High |
| Comments: | Threats were assessed in 2016 which resulted in a score of High; habitat is threatened in long term by forest harvesting, especially the harvest of Western Larch in the Kootenays and Okanagan portion of the population (COSEWIC 2017e). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | G = Relatively Stable (<=10% change) |
| Comments: |
"Inferred 9% reduction in total number of mature individuals over last 10 years, based on observed 9% reduction in habitat over that period." (COSEWIC 2017e). Previous version: Thought to be declining because of loss of mature western larch habitat in the Okanagan, but westward expansion (Campbell et al. 1990b) may compensate. S. T. NATALIAE population thought to have been extirpated, but there have been recent sightings (R.W. Campbell, pers. comm.). |
| Long-Term Trend: | U = Unknown |
| Comments: | ?The Canadian breeding range may have increased during the 1940s, when the Western region appears to have expanded, with sightings in the Princeton area where they had not been previously observed" (COSEWIC 2017e). |
| Other Factors | |
| Intrinsic Vulnerability: | C=Not intrinsically vulnerable |
| Environmental Specificity: | A=Very narrow. Specialist or community with key requirements scarce. |
| Comments: | limited and specific food resource for rearing young being dependent on ants in older forests (literature reviewed in COSEWIC 2017e) |
| Other Rank Considerations: | Appears to frequent mixed Douglas-fir/trembling aspen forest in western part of its range; not as dependent on larch forests as in Okanagan (Cannings et al. 1987). |
| Information Gaps | |
| Research Needs: | |
| Inventory Needs: | Continue to monitor populations through surveys and range (through surveys and eBird) as they appear to be changing. |
| Stewardship | |
| Protection: | |
| Management: | |
| Version | |
| Author: | Fraser, D (2020) and S. Cannings (previous version) |
| Date: | February 14, 2020 |
| References | |
|
Campbell, R.W., N.K. Dawe, I. McTaggart-Cowan, J.M. Cooper, G.W. Kaiser, and M.C.E. McNall. 1990b. The Birds of British Columbia Vol. 2: Nonpasserines: Diurnal Birds of Prey through Woodpeckers. Royal British Columbia Museum, Victoria, BC.
|
|
|
Cannings, R.A., R.J. Cannings, and S.G. Cannings. 1987. Birds of the Okanagan Valley, B.C. Royal B.C. Mus., Victoria, B.C. 420pp.
|
|
|
Chytyk, P. and D.F. Fraser. 2015. Williamson's Sapsucker in Davidson, P.J.A., R.J. Cannings, A.R. Couturier, D. Lepage, and C.M. Di Corrado (eds.). The atlas of the breeding birds of British Columbia, 2008-2012. Bird Studies Canada. Delta, BC.
|
|
|
COSEWIC. 2017e. COSEWIC assessment and status report on the Williamson?s Sapsucker Sphyrapicus thyroideus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xii + 53 pp
|
|
|
Crockett, A.B., and H.H. Hadow. 1975. Nest site selection by Williamson and Red-naped Sapsucker. Condor 77:365-368.
|
|
|
Gyug et al. 2020. Williamson's Sapsucker (Sphyrapicus thyroideus), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA
|
|
Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2020. Conservation Status Report: Sphyrapicus thyroideus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Apr 25, 2024).