1. The Social Use of Space 47 



Fredericson (1951) that animals attempt to make their environment 

 predictable, and if we accept constancy of consequences as assuring greater 

 predictability, then it follows that where the members of a community 

 have their home range centers approximately 2.1 sigma apart, greatest 

 predictability with regard to contacting neighbors characterizes this 

 interval. 



H. Sign Field of AlljNeighbors 



Urination, defecation, and activities relating to the removal of materials 

 used for food or nests represent signs by which one individual might recog- 

 nize the presence of neighbors. Signs left by neighbors may be expected to 

 be proportional to the sum of the density functions of neighbors at points 

 considered. Unless home range centers are extremely close together, there 

 will arise a noticeable increase in signs of neighbors as the individual moves 

 away from its own home range center. Obviously, the closer home range 

 centers are to each other the relatively greater will be the sign of neighbors 

 at any particular radius from the individuals's own home range center. 

 We may then wonder what standard a particular individual may utilize 

 in judging the intensity of signs left by its neighbors. Any individual's 

 own sign is maximal near its own home range center. Therefore, an in- 

 dividual may resort to comparing the relative amount of sign of neighbors 

 at any point to that which it would leave in a similar area near its own home 

 range center. 



Dividing the sum of the density functions of all neighbors at a particular 

 point by the density function of a particular individual near its home range 

 center provides such an index of the relative intensity of sign of neighbors 

 (Fig. 21). The optimum interval between home range centers with regard 

 to the sign field should be that interval at which throughout the home range 

 of a particular individual the total sign left by neighbors nearest approxi- 

 mates that individual's own standard and in which there is greatest pre- 

 dictability with regard to sign, that is in which there is the least variation 

 in intensity of neighbors' signs from point to point. Judging from the three 

 curves presented in Fig. 21 an inter-home range center interval of some- 

 where near 2.1 sigma would lead to the development of an optimum sign 

 field. 



I. Signal Field of Neighbors 



Following the formulation presented in Section VII, C, it is assumed 

 that the signal emitted by one individual can be perceived by another in- 



