. The Canadian field-naturalist. 1976 Notes 357 Results and Discussion The orientation of Golden Eagle nests in the four populations is shown in Figure 2. The Utah and Alaska data show statistically significant directional oreferences (a = ). Utah nests are oriented NNW while Alaska nests are oriented SSE. Montana nests have a significant orientation to the south (J. Baglien, personal communication). McGahan (1968) reported 50% and 48% of occupied cliff nests that he checked in Montana were south-facing during 1963 and 1964, respectively. The Texas values suggest a slight northern preferen
. The Canadian field-naturalist. 1976 Notes 357 Results and Discussion The orientation of Golden Eagle nests in the four populations is shown in Figure 2. The Utah and Alaska data show statistically significant directional oreferences (a = ). Utah nests are oriented NNW while Alaska nests are oriented SSE. Montana nests have a significant orientation to the south (J. Baglien, personal communication). McGahan (1968) reported 50% and 48% of occupied cliff nests that he checked in Montana were south-facing during 1963 and 1964, respectively. The Texas values suggest a slight northern preference but it is not significant. No statistically significant relationship was discerned between elevation and nest exposure within any of the localities. Breeding season schedules and monthly tempera- ture regimens are presented in Figure 3. It appears that Golden Eagle young are susceptible to death by thermal stress during at least the first 6 weeks after hatching. It seems reasonable that nest sites which provide a microclimate within the range of temperature tolerance offer two distinct advantages. First, by avoiding extremes of temperature and insolation the young are protected from death caused by such exposure. Second, shading or brooding time required of the adults would be reduced, with a consequent increase in the time available for other X 24 29 X / ^^ \ / 45 \ \ ^^ / \ 76 / X 63 73 y Alaska 57 46 X / 46 \ / 27 \ \ ^^ / \ 19 / 16 14 y Utah. Montana A 30 30 X 1 " \ / 10 \ \ ° / \ " / X 20 15 y Texas Figure 2. Orientation of Golden Eagle nests. Values are the percentage of nests which are exposed in each sector and (except for Montana) will total to more than 100%. Deviations from random are significant for Alaska, Montana, and Utah. Sample sizes are as follows: Alaska, 62; Montana, 47; Utah, 37; and Texas, 20. O o d) â *-> CO a E .0^ 30 25 20 15 10 5 0 -5 -10 -15 m m rr u. Please note that these images are extracted from scanned page images that may hav
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