Page 23

and pole (range 14.3–67.1%; 32.9 ± 16.1) were the most abundant seral stages (Table 2.1). The young seral stage consisted entirely of forest regenerated after logging. Pileated woodpeckers used all seral stages and forest types in both summer and winter (Fig. 2.1). Confidence interval analyses showed that the most abundant types (mixed and upland spruce) and seral stages (pole and mature) received greater use than expected compared to available habitat. The non-forest type and young seral stage were used less than available habitat. Summer use was greater than available habitat for all forest types in the pole and mature seral stages except lowland spruce (Fig. 2.2). In winter, use was greater than or equal to available for upland spruce, lowland spruce, and mixed in pole and mature seral stages, old mixed, and pole and old deciduous. Nesting season habitat use was not different from nonnesting habitat use. Nesting season territories had more deciduous, mixed, and non-forest types, and the mature seral stage, and less coniferous type and young and old seral stages then annual territories. Within the nesting season territories, forest types and seral stages were used in proportion to available amounts. Elevations <1,100 m, which reflected the distribution of trembling aspen, were used more than available throughout the year. The slope and aspect of used habitat was in proportion to available habitat. At the stand scale all stands received use in approximate proportion to available, with little seasonal variation. Stands 51–125 years old, 18–23 m tall, and 26–70% canopy closure were used more than available. Short (≤5 m), young (≤50 years), and late-mature (125–150 years) stands were used less than available. Stands with trembling aspen and white spruce were used more than available, and stands with all other species were used less than available. Habitat Selection at the Foraging Substrate and Position Scales Pileated woodpeckers foraged on wood substrates (>99.9% of foraging time) and anthills (<0.1%, n = 82 minutes). Wood substrates were dead trees (snags, stubs, stumps; 46.0%), live trees (37.8%), and logs (16.2%). Foraging methods were not different between years (P < 0.01) but changed between seasons (Fig. 2.3). In winter, (November–February) foraging (n = 20,676 minutes) was 94.1% excavating, including 88.3% excavating into hard substrates. Summer (April–September) foraging (n = 14,893 minutes) was 66.8% excavating, including 32.4% into hard substrates, and surface foraging increased to 33.4%. Spring (March) and fall (October) foraging (n = 4,561 minutes) was transitional between summer and winter patterns. In total, birds foraged 83.7% of the time on substrates containing carpenter ants, 8.2% on substrates containing other ant species, and 8.0% on substrates with no visible food items (Fig. 2.3). Substrates with carpenter ants were used for 90.6% of winter foraging time, and 62.5% of summer foraging time. Carpenter ants were observed in all substrate types and sizes except some soft stubs, logs, and stumps that pileated woodpeckers foraged on only in summer. Substrate use by tree species, type, and decay class changed seasonally (Fig. 2.4). Winter foraging was mainly on coniferous species (79.6%), live trees and snags (84.3%), and hard decay class substrates (86.9%). In summer, there was increased use of deciduous species (44.7%), stubs, logs, and stumps (47.7%), and soft decay classes (49.0%). There were no seasonal differences in substrate size by species or type, but mean dbh of species (F 0.05, 5, 3679 = 50.2) and types (F 0.05, 4, 3679 = 125.9) was different. Black spruce substrate mean dbh (21.7 cm) was < all other species (x¯ = 29.0 cm, range 27.5–32.1); and mean dbh of logs (21.8 cm) was < snags (27.4 cm) < stumps (30.7 cm), live trees (31.1 cm), and stubs (31.2 cm; Tukey’s HSD, Ps < 0.001). White spruce was used more than available in winter and less than available in summer; trembling aspen was used less than available except in spring; and balsam poplar was used more than available in summer (Fig. 2.5). There were no clear use patterns for lodgepole pine and black spruce. Dead substrates were used greater than available and live substrates less than available. Snags were used greater than available throughout the year; injured live trees were used greater than available in winter; stubs and logs were used greater than available in summer, and logs were used less than available in winter (Fig. 2.6). Substrates as small as 7.4 cm dbh were used for foraging, but pileated woodpeckers selected for larger substrates (Fig. 2.7). Substrates <20 cm dbh were used less than available, and substrates from 25–50 cm dbh were 13

Pwp 2001 04 rpt phdthesis pileatedwoodpeckerhabitatecologyinabfoothills  

http://foothillsri.ca/sites/default/files/null/PWP_2001_04_Rpt_PhDThesis_PileatedWoodpeckerHabitatEcologyinABFoothills.pdf

Pwp 2001 04 rpt phdthesis pileatedwoodpeckerhabitatecologyinabfoothills  

http://foothillsri.ca/sites/default/files/null/PWP_2001_04_Rpt_PhDThesis_PileatedWoodpeckerHabitatEcologyinABFoothills.pdf

Advertisement