ing “The Syndrome of the Social Outcast” 
(pp. 195 to 196). 
3. Two records are for females aged 116 and 161 
days respectively both of which were in their 
first pregnancy. 
4. Four of the records concern individuals for 
which there is insufficient data to warrant any 
comment regarding associated factors. 
In all the above comments a record refers to all 
the storing activity engaged in by one individual 
during a single night, although in most cases each 
individual noted made several storing trips. Trans- 
portation of food occurred during all months of the 
year. Surveys of the harborage boxes during De- 
cember 1948 and February 1949 showed as wide a 
distribution of food as occurred at other seasons. 
During these winter months there was no repro- 
duction. 
E. The Position of Food Caches in the Harborages- 
The sunken harborage boxes provided were greater 
in volume (12 by 14 by 28 inches) than were the 
cavities (table 4) which the rats excavated in their 
burrows. Normally the nest covered not more 
than one-sixth of the floorspace and was located in 
one corner. Food brought into boxes containing 
nests was deposited in discrete piles, usually in an 
opposite corner of the box. Only rarely was food 
deposited on the edge of the nest or eaten in the 
nest. In the burrows piles of food were scattered 
along tunnels in small enough amounts so that the 
rats could get by them, or they were placed in 
separate terminal cavities in which there was no 
nesting material. 
F. An Extreme Development of Cache Formation. 
During the breeding season of 1948 female 43 had 
4 litters in Area III. This was the most litters had 
by any female during a similar period of time. 
While rearing these litters she formed larger food 
caches than were noted elsewhere in the pen. 
1. April 3, 1948. Box 20. The young of litter 8 
are 20 days old. There are several hundred 
Purina checkers and an apple in the box. 
2. April 16, 1948. Box 28. As I opened the 
box, female 43 ran back into the burrow 
which led through the wall of the box. One 
of her 33-day-old Litter 8 young ran with her. 
Her 10-day-old Litter 13 young are in the 
burrow. In the box are 140 Purina checkers 
carried from the Food Pen last night. Min- 
imum round trip distance of 120 feet between 
Food Pen and Box 28. Therefore, this 
female traveled at least 16,800 feet during 
this one night while transporting food. 
3. April 28, 1948. Box 21. Female 43 is 
nursing her Litter 13 young. She has trans- 
ported at least 100 Purina checkers to this 
box. 
4. June 2, 1948. Box 19. Nine to 12 Litter 18 
young born to Female 43 last night. Twelve 
Purina checkers in corner opposite nest. 
5. June 4, 1948. Box 19. There are now 40 
Purina checkers in cache. 
6. June 8, 1948. Box 19. Female 43 now has 
her 7-day-old Litter 18 young in the front 
nest. I counted 100 Purina checkers and 
estimated the remainder of the food cache at 
over 400. 
7. June 12, 1948. Box 19. Food cache now 
nearly completely covered by dirt excavated 
by female 43 from a tunnel system leading 
through side of box. 
During the fall of 1948 female 43 as well as 
many of her young remained in Area III. Twice 
two huge caches were observed. It was not known 
to what extent these were the work of female 43 or 
to what extent she was assisted by her young. 
1. October 6, 1948. Box 20. Over 2,000 Purina 
checkers in box. I removed all of these and 
replaced them in the Food Pen. 
2. December 10, 1948. Box 20. In this box 
there were 2,200 Purina checkers as well as 
several hundred pine shoots. These branches 
were scattered at random through the checkers 
as if they were food. This indicates that their 
cutting and storage was a food storage 
behavior pattern. However, I have never 
seen any evidence of rats eating these branches. 
Rats in burrow leading from box: Males 56, 
57, 59, 696, 657, and 669; females 58 and 370. 
Only two of these eight rats showed a more 
than average rapidity in rate of growth. This 
retardation of growth may have been a factor 
in the accentuation of the storage behavior. 
However, since six of these rats were the young 
of female 43 there exists the possibility that 
their storage behavior was enhanced through 
a cultural learning process from the association 
with their mother. 
G. The Nonrecognition of the Value of Food. Peri- 
odically the rats clean out their tunnels in conjunc- 
tion with the enlargement of the burrow system. 
At this time dirt, feces, food caches, and nesting 
material are thrown out on the mound. In most 
107 
