. The Canadian field-naturalist. 16 The Canadian Field-Naturalist Vol. 88 <100 yj 75 UJ 50 .25- .00 67. Y=.38+ r=.60 68 1 2 3 MICROTUS PER 100 TRAP-DAYS Figure 5A. Functional response of Red-tailed Hawks to changing Microtus populations (August) near Roches- ter, Alberta. D UJ Z lO y CO CO < O CO 4- 3- 2- 1 i 67 y - y 69 66 ⢠/ -â¢/ /^7Q Y=+ m 68 1 r^=.86 II 1 0 12 3 4 MICROTUS PER 100 TRAP-DAYS Figure 6A. Microtus population indices (August) versus percent biomass of Microtus in the diet of Red-tailed Hawks near Rochester, Alberta. roor IT) S Q S y UJ o °- z o CO UJ Q Q- 5
. The Canadian field-naturalist. 16 The Canadian Field-Naturalist Vol. 88 <100 yj 75 UJ 50 .25- .00 67. Y=.38+ r=.60 68 1 2 3 MICROTUS PER 100 TRAP-DAYS Figure 5A. Functional response of Red-tailed Hawks to changing Microtus populations (August) near Roches- ter, Alberta. D UJ Z lO y CO CO < O CO 4- 3- 2- 1 i 67 y - y 69 66 ⢠/ -â¢/ /^7Q Y=+ m 68 1 r^=.86 II 1 0 12 3 4 MICROTUS PER 100 TRAP-DAYS Figure 6A. Microtus population indices (August) versus percent biomass of Microtus in the diet of Red-tailed Hawks near Rochester, Alberta. roor IT) S Q S y UJ o °- z o CO UJ Q Q- 5 ^ .75 .50 .25 .00 V/ 0 68 ⢠t? 71 70 200 300 400 RICHARDSON'S GROUND SQUIRREL POPULATIONS Figure 5B. Functional response of Red-tailed Hawks to changing Richardson's ground squirrel populations (April) near Rochester, Alberta. 40 r 530 i â 20 5 10 O V' 69 68 70 71 200 300 400 RICHARDSON'S GROUND SQUIRREL POPULATIONS Figure 6B. Richardson's ground squirrel population indices (April) versus percent biomass of ground squirrels in the diet of Red-tailed Hawks near Rochester, Alberta population tended to be slightly lower during April-August 1969-1971 than in 1966-1968 (Table 15). Minimum estimates of predation rates ranged from (1969-1970) to (1967), and max- imum estimates from to Predation on adult and juvenile Ruffed Grouse declined in 1970-1971 from the preceding 2 years (Table 15). The buffering effect of the high hare population seems to have occurred later among red- tails than among homed owls. Rates of predation. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ottawa Field-Naturalists' Club. Ottawa, Ottawa Field-Naturalists' Club
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