Fisure 65. — The position of trails in relation to vertical objects. 
Dots represent tree trunks, solid lines represent trails, open 
circles represent entrances into burrows. 
oriented to the next one kinesthetically. The 
deviation of the trail at X toward Area III and at 
Y toward the route of travel through the East 
Alley to the Food Pen indicates a conflict exerted 
between alternate goals upon the kinesthetic 
orientation of the rat. 
Later trails as on May 15, and December 2, 
1948 (fig. 65 F and G) indicate similar orientations 
to previous ones when there was no snow cover. 
However, as a burrow had developed in the 
North Alley along the median barrier fence from 
Passage 3, the attraction of the rats between this 
burrow and the North Alley Burrow was sufficiently 
great to inhibit occasionally the development of 
trails through the trees in the North Alley. Such 
situations are shown in figures 65 H and I, al- 
though the basic pattern of orientation toward 
tree trunks became apparent again following a 
slight snow on February 11, 1949 (fig. 65J). 
Despite the fact that the trees in the above situa- 
tion were all conifers there was no evidence from 
the trails through the snows that during such 
weather the rats were attracted to the trees as a 
place of retreat with respect to the overhead cover. 
When such an attraction to trees occurs there are 
invariably traces of urine and feces. Apparently 
only extremely momentary hesitations occurred 
along the trails through the snow. Similar close 
duplication of trails over the snow to those pre- 
viously existing over the ground regularly occurred 
in such places as the West Alley where only decidu- 
ous trees were located. It was through the accu- 
mulation of a great many such records that I have 
become convinced that the visual orientation 
toward vertical objects plays an important role in 
the life of the Norway rat. Tactile, olfactory, and 
kinesthetic perception may enhance the point to 
point orientation under some circumstances, but 
where vision is possible, these other means of per- 
ception are certainly not requisite. 
C. The Wall Response. The attraction of rats 
toward the surface of traps or similar objects 
placed near their trails has already been mentioned. 
This may be considered as a special case of the 
response to vertical cues. Vertical cues are fre- 
quently encountered about human habitations in 
the form of board fences or the walls of buildings. 
Examples of this may be seen in any mapping of a 
residential area inhabited by rats (see fig. 2). 
Although the wall response is undoubtedly a real 
one, all trails adjacent to continuous vertical 
objects, such as fences or walls, should not be 
67 
