RANGE OF o' 8 MARCH 14 1947 TO MAY 22, 1948 
N AREA III AREA II E 
Figure 108. — Range of the introduced male 8. The num- 
bers refer to the chronological order of capture. It will 
be noted that he continually shifted his place of residence. 
Each underlined record indicates that he moved to some 
other locality in the pen. He held a very low social 
status. Other rats continually forced him to change his 
place of residence. Furthermore, he seemed particularly 
susceptible to shifting his residence as an immediate result 
of handling by the observer. 
2. Females tend to remain closer to their places 
of birth than do males. This is shown in 
figures 112 to 115. An exception to this is 
shown in figure 111. Here the females be- 
came as widely dispersed as the males: This 
resulted from the fact that both sexes were 
excluded from their place of birth by more 
dominant invading rats. See particularly the 
later discussion of the formation of Colony e in 
1949 in Area III (pp. 207 to 209). Further 
aspects of the differential shifts in place of 
residence with respect to social rank and sex 
have been previously treated in table 30 and 
the accompanying text. 
3. In their dispersion from their places of birth, 
which results in shifts in location of home 
range, young rats avoid neighboring areas 
occupied by socially high-ranking adults. 
The clearest situation pertains to the rats 
born at the South Alley Burrow during 1948 
(figs. 113, 114, 116) with respect to Area I. 
From the spring of 1948 until May 1949, 
Area I was dominated by male 22, female 28, 
and their progeny (figs. 109 to 111). In ex- 
tending the area or shifting the position of 
their home range, rats born at the South Alley 
had equal opportunity to invade Area I or 
Area IV. The latter area in contrast to Area 
I was not occupied by adults, which defended 
the area or were raising young, until late in 
the summer and fall of 1948. There were 
only 25 captures in Area I of rats born at the 
South Alley Burrow, whereas there were 129 
in Area IV. Furthermore, 24 of these 25 
records in Area I were for rats born at least a 
month before female 28 had her first litter in 
Area I. The degree of exclusion is further 
reflected by the fact that only 2 rats born at 
the South Alley Burrow occurred in Area I 
after sexual maturity, and these 2 rats, which 
were accepted into the local colony being 
developed there, accounted for 17 of these 
24 records. 
4. The condition of restriction of home range by 
each rat to only portions of the pen reduced 
the frequency of contact between individuals. 
Examples of this are shown in figures 109 and 
110. It is apparent from these that such 
individuals have essentially no contact with 
each other, except at the food source. It will 
be recalled from the earlier section on perio- 
dicity of activity that rats living in different 
portions of the pen tended to become active 
at different times, thus further decreasing the 
probability of rats living in different localities 
having associations. This role of restricted 
home range in limiting the frequency of paired 
associations is discussed in detail in the later 
section on “The Function of Group Structure 
in Altering the Frequency of Contact Between 
Rats” (pp. 172 to 175). 
This latter section will further emphasize that 
a home range is not an exclusive portion of the 
environment, but rather is one which is shared 
with a number of other associates. The territorial 
aspects of home range are discussed on pages 
184 to 188. 
A cursory examination of the figures (Nos. Ill 
to 116) on places of capture indicated that there 
was a decreasing frequency of captures after wean- 
ing at increasing distances from the place of birth. 
This distance may be considered in two ways: 
1. The shortest distance between the place of 
birth and the place of later capture irrespective 
164 
