During this early adulthood before male 22’s death, 
male 690 harbored in the burrows in the south 
corner of Area IV or at the South Alley Burrow. 
At the time of male 22’s death there were residing 
in Area I in addition to the dominant female 28, 
five females and eight males who were born there 
as well as one male (No. 52, who was the dominant 
male 49’s brother) from Area II. It will be noted 
that male 22 was tolerating the presence of several 
rats which had grown up in his presence to adult- 
hood but who were sexually inactive (testes 
withdrawn into the abdominal cavity) because of 
the cold winter weather. Male 690 also tolerated 
these males through January and February 1949 
after he moved into Area I. During these months 
he lived solitarily and never joined in the harborage 
aggregations maintained during the winter of 
1948-49 by the rats which were born in Area I. 
However, with the advent of the breeding season 
in late March of 1949 all but one of the eight males 
were driven from Area I by male 690. This one 
male (No. 737) was an extremely small individual 
having a mean life span Maturity Index of 11.75, 
so that he certainly offered 690 no serious competi- 
tion over the control of the four of the six females 
who survived through the spring breeding season. 
The dispersal of these eight males as a result of 
male 690’s action is interesting. Five of them 
became members of the all-male colony, which in 
its physical position opposite Passage 1 was mar- 
ginal to the two highest ranking colonies, that of the 
South Alley Burrow and of Area I (see colony k in 
fig. 128). One joined colony c which inhabited 
the burrow in the South Alley by Passage 2, and 
one, No. 95, shifted to Area II. Thus these seven 
males (Nos. 732, 735, 736, 739, 760, 799, and 95) 
settled in localities immediately adjoining the 
place of their birth. The ninth excluded male, 
No. 52 who had originally joined the Area I winter 
aggregation from elsewhere (Area II) made the 
greatest shift in range to the senescing North Aliev 
Burrow which housed an extremely socially low- 
ranking, all-male aggregate (see colony i, fig. 128). 
Thus the assumption of dominance over Area 1 by 
male 690 illustrates how the establishment of ter- 
ritorial defense of an area influences the lives of 
other males. The typical interaction of male 690 
with the higher ranking male 49 of the South Alley 
Burrow was generally one of 690 avoiding or 
retreating from 49 in instances involving priority 
of action, although they frequently ate or drank 
amicably together in the Food Pen. 
Concerning the males of the colony in Area III 
in 1949, there were no behavioral records indicat- 
ing dominance despite extensive observations in 
this colony during April when filming by the U.S. 
Army Signal Corps was underway. The lack of 
observed fighting during a time when male 49 
consistently defended his territory of the South 
Alley Burrow and its environs at least indicates 
that there was less territorial defense. Further 
evidence of lack of fighting among the males of 
Area III is the fact that three of the only five males 
who had no wounds in May 1949 were members 
of this colony. A fourth male, No. 703, who had 
a fairly good growth (mean life span Maturity 
Index of 1.75 with a May 1949 weight of 510 grams) 
and who with the other three slightly smaller males 
was accepted in the burrow by the nine females, 
might have been the dominant male, although I 
doubt it. He had nine body wounds. The fifth 
male, No. 786, was more likely the dominant one. 
During May 1949 he was the heaviest male in the 
pen, 583 grams, despite the fact that he had a less 
favorable earlier growth than several of the other 
males. His 25 wounds in May 1949 (male 49 had 
26) certainly did indicate that he frequently en- 
gaged in combat and it is unlikely that he lost 
since he weighed from 40 to over 100 grams more 
than any other male with whom he had occasion 
to come in contact. During the 1949 breeding 
season he lived a solitary life residing in harborage 
boxes away from other rats. Assuming that he 
was the dominant male and that it was his activities 
which maintained the exclusion from Area III of 
the many males inhabiting the immediately adjoin- 
ing localities, his past history becomes particularly 
interesting. He was a member of the last litter 
born in 1948 at the North Alley Burrow and all of 
his three sibs were females. This reduced compe- 
tition. Furthermore, the lateness of his birth pre- 
cluded the possibility of his receiving aggressive 
action from lactating females following his own 
weaning. He remained at the North Alley Burrow 
until about the time in 1949 when the reproducing 
females in Area III began coming into estrous. 
Just preceding the breeding season there were 10 
males residing in Area III. Five of these (Nos. 74, 
82, 89, 657, and 909) were among the 15 males 
weighing over 525 grams. This formed quite a 
concentration of large males in Area III when 
one considers that there were 69 adult males at 
that time in the pen. Their being here also indi- 
cated that Area III had become a more favorable 
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