Figure 121. — Routes followed during one of three similar 
chases of female 20 by female 1 0 on October 3, 1947. 
Chases frequently terminated as did this one with ihe 
subordinate rat escaping into an area, with the dominant 
rat paralleling it, but traveling along the alley side of the 
median barrier fence. 
chasing as soon as it reached or had just passed 
through the passage. In many such instances 
the pursuer would then engage in sexual rubs 
against the passage or pawings of the earth about 
it. This might happen whether or not the incep- 
tion of the chase appeared to have any relevance 
to sexual behavior. Similar sexual behavior also 
frequently followed other types of aggression not 
characterized by chases. The association of these 
behaviors suggests that aggression increases erotic 
responses. 
Chases which terminated at passages through the 
fences usually were initiated in the Food Pen or in 
the alleys and proceeded outward toward the 
areas. Less frequently rats in the areas chased 
other rats from one area into another or from an 
area into the alleys. Whereas most chases from 
areas appeared to have territorial implications, it 
was quite clear that as often as not, the outward 
chases from the alleys were merely expressions of 
dominance relationships. It might be added that, 
although chases might occur from the Food Pen 
or from the alleys through the Food Pen, they 
rarely terminated at the passages through the fence 
surrounding the Food Pen. Correlated with this 
was the fact that the territorial behavior of passage 
guarding (p. 187) rarely occurred at these Food 
Pen passages. It may be seen from these comments 
that chases were a potent factor in dividing the 
population into the more favored alley inhabiting 
rats versus the less favored area inhabiting rats. 
Certain conditions may now be listed which 
influence the occurrence of aggression in the form 
of chases. 
1. Territorial defense. 
2. The nonreceptivity of females. In the latter 
stages of estrous females were still attractive to 
males, but repelled their advances. 
3. Lactation. Laciating females were particu- 
larly aggressive in defending the vicinity of 
their burrow against alien rats. Such aggres- 
sion toward males was also expressed in the 
Food Pen to a lesser extent, but it is interesting 
that remarkably little aggression of any sort 
was exhibited between lactating females in the 
Food Pen, even though they inhabited 
different localities. 
4. Antagonism of adults toward subadults rang- 
ing between 80 to 115 days, which were just 
becoming sexually mature. This category was 
primarily confined to male-male relationships. 
5. The act of moving away by one rat may elicit 
the pursuit of it by another rat. This is a 
counterpart of fleeing by a previously sta- 
tionary rat upon its approach by another rat 
running toward it. Either the pursuing or the 
fleeing in these cases, initiated by another rat 
in motion, may be entirely dissociated from 
recognition of social rank by this responding 
rat. Frequently the rat which is pursued 
after it moves away from another rat initiates 
its retreat at such an angle from the approach- 
ing rat as to make visual recognition of the 
pursuer difficult. The pursuits which arise 
under these conditions are usually of short 
distance (2-5 feet). It is as if pursuit is a 
learned response triggered by the movement 
away by another rat, but that pursuit is 
shortly terminated when the actions of the rat 
moving away in some manner convey to the 
pursuer that this is not the fleeing of a socially 
low-ranking individual. The moving away 
(usually 2-5 feet) from a rapidly approaching 
rat has the functional significance of giving the 
rat which moves away an opportunity to turn 
and recognize the approaching rat. Both of 
these behaviors were most frequently observed 
in the Food Pen, although they were noted 
elsewhere. 
182 
