. The Canadian field-naturalist. 2004 Erickson: Bird Communities of Garry Oak Habitat 377. Present distribution of Garry oak ecosystems in British Columbia Figure 1. Garry Oak range in British Columbia. This map is courtesy of British Columbia Ministry of Water, Land and Air Protection, December 2003. ering an area bounded by East Sooke, Gonzales Hill and Courtenay on Vancouver Island; and East Point, Satuma Island, and Helliwell Point, Hornby Island on the Gulf Islands (Erickson 1996). These locations are between approximately 48°N, 123°W and 49°30'N, 125°W. The Garry Oak stands sampled were
. The Canadian field-naturalist. 2004 Erickson: Bird Communities of Garry Oak Habitat 377. Present distribution of Garry oak ecosystems in British Columbia Figure 1. Garry Oak range in British Columbia. This map is courtesy of British Columbia Ministry of Water, Land and Air Protection, December 2003. ering an area bounded by East Sooke, Gonzales Hill and Courtenay on Vancouver Island; and East Point, Satuma Island, and Helliwell Point, Hornby Island on the Gulf Islands (Erickson 1996). These locations are between approximately 48°N, 123°W and 49°30'N, 125°W. The Garry Oak stands sampled were primarily mature, but their canopy varied from shrub-like with exposure, to large and open on deep soils. Elevations ranged from sea level to about 550 m. Plots were approximately 200 m-, consisted of relatively uniform vegetation and topography, and varied in size accord- ing to plant community boundaries. Species presence was recorded in an observation effort of approximately 90 minutes per plot. A total of 1243 records were taken on 286 plots (Erickson 2(XX)b). Sampling was primarily in spring, during May and June. This time interval has migratory bird influx, spring vegetation growth, territory establishment, nesting, summer plant growth cessation and bird dispersal. The data set had been previously checked with spe- cies accumulation curves (McCune and Mefford 1997; Erickson 2000b, unpublished data; Smith et al. 2002) to determine the adequacy of the sample. Occurrence by plot of all species with a frequency >5% for each year was entered into a data set; 23 species in 1993, and 29 species in 1994. This qualifying criterion reduced the number of plots to 135 in 1993 and 127 in 1994, for a total of 262 in the analysis. The DCA method uses chi-squared distances to simultaneously ordinate, in this case, bird species data against plots, and vice-versa. Axis solutions account for, and therefore represent the most variation in the data set. Bird species are sepa- rated and
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