2 . Steiniger's Study of Group Behavior of 
Rats 
During approximately the same years I made mv 
studies of Norway rats in an enclosure near Balti- 
more, Steiniger ( 40 ) conducted quite similar 
studies. Since his study and mine are the only ones 
to date which have attempted observation of 
group behavior under simulated natural condi- 
tions, it will be well to mention those areas in which 
his observations corroborated mine, as well as those 
conclusions which are additional or contrary to 
mine. 
His enclosed pen was only one-sixteenth (i.e., 64 
square meters) of mine. This much smaller area 
must have accounted in part for the more marked 
antagonism he noted among his rats. Another 
contributing factor was that groups of strange rats 
were periodically added to the pens. Furthermore, 
the surface of the pen was unstructured by any 
barriers which would permit evasion and retreat 
of subordinate rats from their superiors. Except 
for occasional peculiarities due to size or wounds, 
individuals were not identified, and thus observa- 
tions relate only to those having obvious differences 
in size or sex. He presents much additional infor- 
mation concerning behavior of rats based upon 
his observations of feral colonies. 
When entire groups of new rats were introduced 
in the absence of prior residents marked fighting 
ensued. Usually only one male and one female 
survived this ordeal which might last 2 weeks. In 
this process males usually killed males, and females 
killed females. A much more stable group devel- 
oped from such a pair in which second and third 
generation members formed a closed group. 
Among these there was considerable tolerance. 
Younger members were permitted to take food 
from their elders with only mild, if any, rebuff. 
However, introduced alien rats were usually at- 
tacked and killed. At these times of heightened 
emotional state, members of the previously peaceful 
ingroup would attack each other. [I have noted 
the same phenomenon among house mice (76)]. 
However, these latter attacks usually terminated in 
more peaceful interactions such as mutual nuzzling. 
When a member of an ingroup (Rudle) was 
removed to the laboratory for several days it was 
usually attacked upon its replacement — just as if 
it were an alien rat. 
Steiniger cites two escape behaviors which I 
never observed in my larger pen. The rat being 
pursued either attempted scaling the wall or it 
would stop suddenly with its head against the earth 
and its posterior elevated with its tail trembling. 
I suspect that both of these behaviors are abnormal 
concomitants of confinement in a space too small 
to permit escape. 
The process whereby only a single pair survive 
from an original 10-15 introduced rats is designated 
as territory or precinct (Revier) formation. The 
concept of territoriality is hardly appropriate to 
these confined quarters (circa 26 by 26 feet), since 
exclusion of subordinates could only occur by their 
death. 
However, Steiniger’s concept of the development 
of a peaceful Rudle or ingroup is probably sound, 
even though outgroup members were only present 
in the sense of introduced aliens until they were 
killed off by the ingroup members. Amicability 
persisted between parents and progeny even 
through the time when the latter were in turn 
rearing young. Likewise, amicability usually per- 
sisted between adult sibs. The importance of these 
observations is that rats reared together are more 
tolerant of each other than they are toward intro- 
duced aliens, or than are rats unfamiliar to each 
other when introduced into a strange situation. 
Steiniger is quite vague as to the duration of his 
studies, number of rats in groups, their age, etc. 
Yet it is quite apparent that tolerance among 
ingroup adults did involve development and accept- 
ance of hierarchial roles. He cites an instance of 
a fight between two 7-month-old brothers which 
terminated in one receiving a deep laceration. 
The latter always avoided his brother in competitive 
situations. Sham battles, that is boxing followed 
first by one rat being forced over on its back and 
second by both rolling over and over while holding 
on to each other, was observed among both juve- 
niles and adults of the ingroups. Such interactions 
not involving gross wounds, as well as those in- 
volving the kicking of one rat by another, are 
classified as “play” by Steiniger. Had Steiniger 
marked his rats for visual identification I suspect 
that he would have found that one of two such 
interacting adults usually assumed the subordinate 
role. 
Steiniger’s account of sexual behavior duplicates 
in nearly every detail my own account, except that 
he makes no mention of the preliminary phase of 
sexual rolling and rubbing at female scent spots. 
He says that the male scratches the female’s back 
as he mounts. Perhaps this is so, but even in my 
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