Les.W. Gyug,1,5 I. Penny Ohanjanian,2 Christoph Steeger,3 Irene A. Manley,4 and Peter W. Davidson5
1 Okanagan Wildlife Consulting, 3130 Ensign Way, Westbank, B.C. V4T 1T9; e-mail: firstname.lastname@example.org
2 4481 LD Ranch Road, Kimberley, B.C. V1A 3L4
3 Pandion Ecological Research Ltd., 532 Park Street, Nelson, B.C. V1L 2G9
4 1893 Irving Road, Castlegar, B.C. V1N 4N6
5 3247 37th St. S., Cranbrook, B.C. V1C 6Z9
Abstract: Relative densities of adult Williamson’s Sapsuckers (Sphyrapicus thyroideus) in British Columbia were assessed between 1997 and 2006 using call-and-drum playbacks (CPB) with follow-up nest searches to confirm relative breeding densities. Nesting density was determined at two census sites. A review of available records showed that the breeding range had expanded 50 km north of Kamloops and 65 km north of Cranbrook since last reviewed in 1995. The average relative adult density was 6.7 detected/100 CPB points (N = 4266). Highest adult densities (10-15) were in portions of the Interior Douglasfir biogeoclimatic zone in the Okanagan and in the Western population. Much lower densities (2-3) were found in the East Kootenay population. Nesting was confirmed at 61% of the sites where Williamson’s Sapsucker were detected with CPB surveys in the Okanagan but only at 44% in the East Kootenay, and 22% in the Western population. The high relative density of adults in the Western population appeared to consist of many non-breeding males or unsuccessful breeders. Fewer nest trees were discovered in the East Kootenay (10), than in the Western population (33) or in the Okanagan (127). In the East Kootenay, several nests were discovered prior to 1938 but only a single nest was found between 1938 and 2004, and it was thought they might have been extirpated, or that the population was very small. We do not know if the 8 active nests discovered in 2006 represent an actual population increase, or if intensive CPB surveys were required to reveal a small population that was always present. The nest density of 3.1/km2 (7 nests in 2.26 km2) in a census site east of Okanagan Falls is the highest density yet found in B.C., and is one of the highest known throughout the range of the species. Large areas in B.C., particularly to the west of the Okanagan and in the East Kootenay, still remain to be surveyed for presence of Williamson’s Sapsucker or confirmation of breeding.
Key words: Williamson’s Sapsucker, Sphyrapicus thyroideus, relative density, nest density, British Columbia, distribution
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