1. The Social Use of Space 55 



than on the preceding day. At this Alberta site, the inhibition of Clethri- 

 onomys home ranges by Peromyscus must have been less than the inhibition 

 of home ranges of Peromyscus by Clethrionomys in the Adirondacks. 



Despite the paucity of areas from which extensive comparable data are 

 available, it looks as though Clethrionomys has a slight advantage over 

 Peromyscus in gaining psychological ascendency. At this point one may 

 suspect that the characteristics of some environments will markedly favor 

 the reproduction and survival of one of these genera. Whichever genus 

 this happens to be will then become psychologically dominant to the other, 

 as evinced by the contraction of home range of the less numerous genus. 

 Consideration of other aspects of the relationship between these two 

 genera requires familiarity with the concept of the constellation dealt 

 with in the following sections. 



B. Removal Captures of Socially Dominant Species 



In several studies already presented (Figs. 9-13) we have seen that one 

 species tends to be caught in large numbers during the first few days, and 

 that the time of maximum input for the remaining species comes during a 

 successively later period. Very frequently a secondary increase in daily 

 catch starts near the 1 oth day of trapping for the species with initially the 

 greatest rate of capture. Such species will henceforth be designated as the 

 socially dominant or alpha species of the small mammal community. For 

 example, see Cleihrionoviys in Fig. 9 and Perotnyscus in Fig. 10. Where 

 there are several species taken, usually only one is characterized by this 

 secondary input. Four censuses examined included one such species and 

 a fifth included two with definite secondary inputs.^ 



Although several species are involved in this phenomenon, the assump- 

 tion is here made that they all so behave because of similar properties 

 leading to their alpha rank in the community. If this is so, we are justified 

 in pooling the data. A table of the total catch per day of trapping was 



^ The five censuses utilized in preparing Fig. 24: 



1. By Dr. J. E. Moore, Sept. 1959, Edmonton, Alberta: 128 Peromyscus maniculatus 

 borealis, 65% of 30-day total by day 14-15. 



2. By Dr. A. I. Roest, Oct.-Nov. 1959, San Luis Obispo, California: 75 Dipodomys 

 heermanni, 65% of 30-day total b}^ day 15-16. 



3. By Dr. William L. Webb, Fall 1952, Rich Lake Island, Newcomb, New York: 

 97 Clethrionomys g. gapperi, 65% of 30-day total by day 7. 



4. By Dr. Earl F. Patric, Fall 1953, Arbutus Area, Newcomb, New York: 86 

 Clethrionomys g. gapperi, 65% of 30-day total by day 12-13. 



5. By Dr. Kyle R. Barbehenn, Nov.-Dec. 1959, Chadwick Woods, Montgomery 

 County, Maryland: 57 Peromyscus leucopus, 65% of 30-day total by day 14; 

 116 Blarina brevicauda, 65% of 30-day total by day 20-21. 



