AREA m 
AREA HI 
Figure 71. — Orientation of rats over and under snow. The broken lines indicate the trails over snow compacted to a depth 
of 3 inches and covered with a crust of ice. These were developed between January 24 and February 3, 1948. The 
solid lines indicate the subnivian trails that were developed through the 10-inch deep snow that fell on top of this ice- 
crusted snow. Letters refer to segments of the subnivian trails discussed in detail in the text. See figure 73B and accom- 
panying text for further remarks on the "olfaction” trail of January 29. Dots represent positions of tree trunks. 
Pen. Initially the subnivian snow trail departs 
from the prior route and heads in the general 
direction of the South Alley Burrow, hut at about 
the place of Box 7 or just beyond it the trail 
turns back and follows along the preexisting 
route. I doubt that the orientation of the trail 
wa influenced significantly by the South Alley 
Burrow. The reason for believing this is that 
Box 9 at this time was inhabited by three socially 
low-ranking females (Nos. 17, 20 and 25) who 
utilized this burrow system as a way station much 
less frequently than did other rats harboring in 
Area I. It will be noted that the initial divergence 
comes fairly close to bisecting the angle between 
76 
