32 



John B. Calhoun 



Laboratory on Mt. Desert Island formed the trapping procedure in the 

 Alaine study. Four concentric circular traplines, each of a 75-feet greater 

 radius than the next innermost one, having one trap each 10 feet along the 

 lines, formed the trapping procedure in the Maryland study. During the 

 years these studies were conducted, I was still working under the assump- 

 tion (see Calhoun and Webb, 1953) that the large numbers of animals 

 taken shortly after the first 3 days of trapping resulted primarily from in- 

 vasion from beyond the periphery of the trapping area. These relatively 

 short-term removal studies are presented here (Fig. 13) since they provide 

 further insight into the differential rate of input for the several species 

 making up the small mammal community. Total lo-day catch by genus 



DAY OF TRAPPING 



5 10 15 



DAY OF TRAPPING 



Fig. 13. Two short-term removal studies. The more dominant a genus happens to 

 be the sooner will 50% of its members be trapped. In Fig. 13.\: B = Blarina; P = 

 Peromyscus. 



for the Maine study (Fig. loA) : Clethrionomys 80, Sorex 53, Peromyscus 

 75, and Blarina 132. Total 14-day catch by genus for the Maryland study 

 (Fig. 13B) : Peromyscus 45, Blarina 76, and Pitymys 62. The Maine study 

 was conducted by A. Dexter Hinckley under the author's direction, and 

 the Maryland study was conducted by the author. 



F. Comparative Catches of Peromyscus and Clethrionomys 



Relationships between these two genera, revealed by NACSM census 

 data, have been particularly helpful in developing insight concerning com- 

 munity organization. Census from three localities, where both genera 

 occur, are represented by a large number of traplines. Those run in each 



