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if ≥0.5 of the base was within the plot. For cavity tree analysis, all live trees, snags, stubs, stumps, and logs ≥10 cm diameter at the top (stumps, stubs, and logs <1.3 m height), or breast height (trees, snags, stubs, and logs ≥1.3 m) were measured in 504 0.04 ha circular plots. Half of the plots were centred on arbitrarily selected cavity trees. Each of these was paired with a plot located using a random numbers table to repeatedly select a compass bearing and distance (measured by pacing) from the cavity tree until the plot location fell within the cavity-tree stand and did not overlap with the cavity tree plot. Random plots were centred on the closest tree to the paced plot location. Each plot was divided into quarters using cardinal compass bearings. I calculated an openness index by measuring the distance from the cavity or centre tree to the 2 closest trees in each quarter and summing the total. For habitat analysis, I used data for live trees and snags ≥10 cm dbh from 3,000 permanent 0.8 ha square plots systematically located in the corners of a 1.6 km2 grid covering a 1 million ha area that encompassed the pileated woodpecker territories (Weldwood of Canada, unpublished data). From these, I randomly selected 25 plots from each forested (≥6% canopy closure) forest type for the pole, mature, and old seral stages (n = 375 plots). Data for stubs, logs, and stumps was not available from permanent sample plots, so I used data for these substrate types from random plots established for cavity tree sampling (n = 74) and an additional 126 0.04 ha plots located within territories, for a total of 10 plots for each type/stage combination (n = 200). The extra plots were randomly selected from type/stage maps and located by pacing along compass bearings from reference points visible on aerial photographs. I estimated availability of substrates by multiplying proportions or means derived from the plot data for the total area sampled by forest type and seral stage times the proportion of each type/stage combination in each MCP area. Statistical Analyses I used 95% simultaneous confidence intervals for multinomial proportions (Bailey 1980) to determine if pileated woodpeckers selected categorical habitat variables disproportionately at different scales. The Bailey (1980) intervals performed better than binomial intervals (Byers et al. 1984) in a comparison test (Cherry 1996). I did not conduct power analyses, but sample sizes for most comparisons were sufficient to yield statistically significant differences between proportions that differed by 1–5 %, so it is unlikely that biologically relevant differences were missed because of low power. I used paired t-tests and ANOVA to compare average values for the variables used by pileated woodpeckers to the average values of variables for available habitat at different scales. I compared observed use of variables in summer (April–September) and winter (November–February) with their proportional abundance for: (1) all birds compared to the sum of available habitat in all 14 territories; and (2) all birds within each territory compared to available habitat within each territory. Each comparison was conducted by comparing observed use to available habitat using: (1) cumulative MCP area; (2) annual MCP area; and (3) nesting season MCP area. I used chi-square tests to compare male and female habitat use between years within each territory and all males compared to all females. RESULTS Habitat Selection at the Territory and Stand Scales From 1993–1996, I obtained 7,189 locations and observed 36 (radiotagged n = 32) pileated woodpeckers in 14 territories for a total of 52,138 minutes. Birds spent 85.9% of their active time foraging, and did not use different habitats for foraging and other activities except for nesting and roosting, which were focussed on stands with cavity trees. Habitat use between sexes and between years did not differ, so data were combined for subsequent analyses. Analyses using all radiotagged birds were generally similar to analyses comparing territories (n = 14) and individuals (n = 20), although there was considerable variation. Only group results are reported. Territories were 72–100% forested, and terrain varied from flat to moderately steep (≤70%) slopes between 948–1,517 m elevation. Coniferous types (upland spruce, pine, lowland spruce) were 38.3–90.1% (59.7 ± 14.9; x¯ ± SE) of each territory. Mature (range 12.7–68.1%; 39.4 ± 16.3) 12

Pwp 2001 04 rpt phdthesis pileatedwoodpeckerhabitatecologyinabfoothills

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