4. July 12, 1948 
6:30 p.m. 
5. May 19, 1948 
6:15 to 7:12 p.m. 
6. October 7, 1948 
7 p.m. 
7. January 21, 1948 
10:30 to 11 p.m. 
The number of rats visible at any one time is greatly reduced from what it 
was an hour ago. 
Essentially no activity of young rats. There has been much more adult 
activity than I have been able to see or record. 
Although there is still considerable activity in the Food Pen, including 
eating and drinking, I believe, that there has been a shift in the past 15 
minutes to other types of activity, as evidenced by an increase in activity 
around the South Alley Burrow, and the amount of gnawing heard. 
Only a few rats are active. They exhibit a wandering about not in evidence 
earlier in the evening. The rats which do go into the Food Pen mostly 
ignore the garbage. 
8. June 1, 1948 
7:50 p.m. 
8:55 p.m. 
(7:55 to 8:55 p.m. — 
9:16 p.m. 
9:19 p.m. 
9:20 p.m. 
9:30 p.m. 
9:50 p.m. 
9. April 25, 1949 
2:40 a.m. 
Rats quite active. 
Only three to five rats were in Food Pen at a time. 
I was gone from observation tower.) 
Only one or two rats in Food Pen at a time. There were corresponding 
decreases in the other parts of the pen. 
Not a single rat to be seen. 
The lull began to break. Gradually rats began to emerge from the South 
Alley Burrow. Their caution parallels the usual late afternoon behavior. 
Rats fairly active. 
Rats nearly as active as at 7:50 p.m. 
Activity has nearly ceased. There has been considerable activity over the 
pen and in the Food Pen most of the prior part of the night. This must 
represent the characteristic slump of activity between midnight, and the 
predawn increase. I was out of the observation tower between 2:45 and 
3:55 a.m. By the time I returned rats had again become quite active and 
this continued until shortly after 5:10 a.m. 
A general summary of the situation is as follows: During the early dusk period rats gradually emerge 
with cautious hesitant behavior. Although rats frequently pass through the Food Pen in their intiial 
activity, they pay little attention to food, but rather engage in various investigatory and wandering 
behavior. There follows an intense period of activity related to the consumption and storage of food. 
This is again followed by a period of investigatory and other nonfood oriented behavior, although rats 
still pass through the Food Pen, before most of them again return to their burrows. Normally several 
additional such periods of activity and quiescence occur during the night with activity gradually ceasing 
shortly after dawn. 
Time, space, and social stratification of activity. 
1. May 18, 1948 
7 p.m. 
2. June 1, 1948 
3. June 28, 1948 
5:50 p.m. 
6:35 p.m. 
No rats active about the North Alley Burrow (although it contained at 
least female 42 and her seven 51 -day-old young), while many rats were 
active about the South Alley Burrow. 
Other than female 42 and two or three young the North Alley Burrow has 
been markedly deserted in comparison with the South Alley Burrow rats 
who have been quite active. 
The South Alley Burrow juveniles are quite active, as they have been since 
the rats first became active at 5:05 p.m. Most of the active rats are about 
the South Alley Burrow or over in the West Alley. No rats have been seen 
at the North Alley Burrow. 
Rats have been out 1 % hours, yet none have been seen at the North Alley 
Burrow, or in Areas II or III, except for one rat who came through Passage 
3 and up Path 3. 
133 
