of females is primarily associated with lactation. 
Presumably the habit of storing during lactation 
may become sufficiently fixed that transportation 
of food for storage will continue at an increased 
rate even after the termination of lactation. Other 
conditions being equivalent animals of lower social 
rank engage in more storage activity than do higher 
ranking individuals. Storage of food in harborages 
occurs at all seasons of the year. My notes are 
inadequate to indicate whether there is any effect 
of seasonal changes in the weather on storing. 
These statements summarize the general conclu- 
sions regarding factors affecting intensity of storage 
activity. The following are samples of the types of 
observations upon which these conclusions were 
based: 
Age and storage: 
1. June 1, 1948. The first Purina checkers in 
a week were available tonight. All ages of 
both sexes except the month-old young of 
female 37 have been seen to transport food. 
2. Although prior food deprivation no doubt 
affected the storage activity noted above, a 
subsequent checking of my notes showed that 
rats of all ages stored at other times as well. 
For 87 records the mean age was 259 days, 
when only those rats between the ages of 
100 and 500 days were included. Age and 
number of storage trips: 125, 6; 175, 12; 225, 
5; 275, 23; 325, 18; 375, 10; 425, 11; 475, 2. 
It must be noted that most of my notes on food 
transportation by recognized individuals came 
during the first (1947) breeding season. Once I 
had become satisfied that food transportation was 
a rather general phenomenon most of my notes 
concerned social interactions between individuals. 
Therefore, the data which I have on food transpor- 
tation is not nearly as adequate from a quantitative 
standpoint as it might have been. Nevertheless, 
the few records on recognized individuals provide 
a basis for a few general statements. Each record 
includes all the observed instances of storage by one 
rat on a particular date. 
Concerning males: 
1 . Low social rank definitely was associated with 
increased storing. Male sibs 57 and 59 of 
Litter 13 who had a very retarded growth rate 
(fig. 139) and who all during their lives were 
frequently subject to the punitive action of 
their associates stored food. Likewise one of 
the original males No. 8 exhibited storing. 
This rat waB particularly subject to punitive 
action from the more dominant original male 
12. However, the social status of male 12 
gradually shifted as he aged so that by the 
time he was approximately 600 days of age 
many other rats dominated him. For the 
final nearly 200 days of his life he was re- 
peatedly seen to transport food to distant 
harborages, although he was never noted to 
do so earlier. Sixteen of the 41 records of 
recognized individuals transporting food are 
encompassed by these 4 rats. 
2. Low social status, however, is not a prerequi- 
site for inducing storing behavior. Attain- 
ment of a high social status is correlated with 
the exhibiting of a rapid rate of growth to a 
relatively large mature size (pp. 203 to 236). 
Twenty-one of the remaining 25 records of 
storing by males were for those individuals 
having such favorable growth rates. 
Concerning females: 
1. Thirty-eight of the 55 records for recognized 
females refer to individuals for whom the age 
of their last litter was known (see table 20). 
It will be seen from this tabulation that 
storing practically ceases by the end of the 
fifth 10-day period of age of the young. This 
roughly coincides with the time at which 
young rats have been noted to begin their 
storing activity. 
Table 20 . — Storage of food by females in relation to the 
age of their last litter 
Age of last litter in days 
Number of rec- 
ords of storing 
behavior 
1-10 
9 
11-20 
9 
21-30 
3 
31—40 
3 
41-50 
9 
51-60 
1 
61-70 
1 
71-80 
2 
81-90 
1 
2. Eleven of the records refer to females, 7, 20, 
25, and 58; all of which have long histories of 
much punitive action from their associates. 
Most of the instances for storage included in 
the records for females 7 and 58 were of the 
nonharborage type discussed under the head- 
106 
