8 John B. Calhoun 



III. Behavioral Origins of the Bivariate Normal Type of Home Range 



The fact that a particular equation happens to describe home range 

 enables derivation of several principles regarding the use of space by an 

 entire community. Discussion of these principles follows in Section VII. 

 However, as a background to this discussion it will be advantageous to 

 seek an understanding of the biological basis for the bivariate normal type 

 of home range. 



A. Activity in a One-Dimensional Habitat 



Admittedly, animals rarely live in essentially one-dimensional environ- 

 ments. However, I suspected that if animals were placed in such environ- 

 ments certain regularities of behavior might be revealed which would pro- 

 vide insight into their use of two-dimensional environments. To this end, 

 four 14-foot long alleys were constructed. Each had a channel 8 inches 

 wide. Each 8 X 12-inch segment of the floor was so suspended that when 

 a domesticated Norway rat, used as a subject, stood on such a segment a 

 microswitch closed. This closure initiated a signal such that the exact 

 position at every point in time was recorded on a recording oscillograph. A 

 partition between the first and second treadles formed a home compart- 

 ment. A 3 X 3-inch opening through this partition provided access to the 

 rest of the alley. Food and water placed in this compartment further en- 

 hanced the role of this compartment as a "home." A ground glass plate, 

 through which shone the light from a 100-watt lamp, formed the opposite 

 end of the alley. This light served to concentrate the activities of the rats 

 emanating from the home compartment. It was as if every foot of the alley 

 were several feet long. Details of the effect of varying light intensity at the 

 end of the alley on explorations will be presented elsewhere. This ap- 

 paratus is referred to as the Ferguson Activity Alley. 



Suffice it to consider the results from 73 rats, each run for 72 hours in 

 the alley. Each rat made from 10 to 30 excursions out into the alley each 

 night. Despite the presence of the bright light at the end of the alley, one- 

 fourth of the trips terminated at the end of the alley. In other words, the 

 end of the alley formed a barrier. Most of the trips thus terminated at the 

 end of the alley presumably would have represented trips of greater length 

 had the alley only been longer. Most of the time a rat would go out to some 

 intermediate distance, stop momentarily, and then turn around and go 

 directly back home. Occasionally, a rat would wander back and forth from 

 the point of initial termination. All trips with such vacillations and those 

 ending at the barrier were excluded from the initial analysis. 



