THE NATURE AND CONSEQUENCE OF SOCIAL 
BEHAVIOR AND SOCIAL ORGANIZATION 
Each rat in the course of its day-to-day activities 
comes into contact with other members of the pop- 
ulation. Such contacts may be random as when 
tw r o rats happen to arrive at the same point 
simultaneously. Where such a chance encounter 
results in an alteration in the behavior of one or 
both of the rats, this resultant behavior is considered 
as a social one. For example, the two rats may sniff 
each other or one may quite obviously turn and flee. 
On the other hand, some encounters embody an 
aura of purposeful intent as in the searching for 
estrous females by males or when a dominant male 
runs toward and attacks other males approaching 
his home burrow. From many such social behav- 
iors there results spacially localized aggregates 
among each of which there exists mutual attraction 
among members and intolerance of members of 
other aggregates. This state of relationships is 
designated as social organization. 
There can be little doubt that rats have some 
awareness of this social organization. However, 
I do not mean to imply that this awareness en- 
compasses the particular ways in which I have 
attempted to formulate social organization. My 
endeavour shall simply be to describe the relation- 
ships which developed and their consequences for 
the individual or the group. 
1 . General Account of the Changes Occurring 
Throughout the History of the Colony. 
A. Introduction and Adjustment. On February 4, 
1947, seven male and seven female rats caught on 
Parsons Island in the Chesapeake Bay (see Intro- 
duction) were released into the Food Pen. These 
rats were confined there by plugging Passages 5 to 8. 
Two tasks faced these rats, (a) They had to de- 
velop a social organization. Most of the rats had 
been trapped from different local colonies, therefore 
it was quite likely that they had few associations in 
common, (b) They had to learn a rather com- 
plexly structured environment. 
Stage 1: February 4 to 12, 1947. The rats were 
introduced into the Food Pen at 4 p.m. with all 
exits sealed. Their initial reaction was to run 
around the periphery of the pen, climb the fence to 
the glass-screen overhang and jump to the ground. 
This indicated an inability to get over the barrier. 
At 5 p.m. five of the boxes similar to those used for 
artificial harborages in the areas were placed in the 
Food Pen. The one placed in the center had a 
4-inch hole in one end and contained newspaper 
for nesting material. One each was placed halfway 
between the food box and the corners of the Food 
Pen with the entrance pointed toward the central- 
food box. By 6 p.m. only two rats had entered 
harborage boxes, while the rest still roamed about 
the periphery of the Food Pen. The boxes were 
then shifted to the edges of the pen and the rats 
herded in, after which the boxes were replaced in 
their former position. By 10 p.m. the rats were 
running between boxes. By that time the rats 
climbed no more than a foot up the fence. 
Number of rats in the 4 boxes in following days: 
February 5: 4, 2, 6, 0. 
February 6: 0, 1, 2, 11. 
February 9: 1, 0, 4, 4, 5 (in a newly dug 
burrow). 
February 10: 1, 1, 0, 6, 6 (in the newly dug 
burrow). 
February 12: 0, 0, 0, 6, 8 (in the newly dug 
burrow). 
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