Table 1 — Relative density, diversity, and other attributes of small mammal populations in a willow- 

 dominated beaver pond ecosystem and adjacent nonwillow riparian habitat, Summit Creek, ID, 

 1988-1989 







Relative density 







Foraging 



Number/100 trap nights 



Number trapped/ha 



wpvcios anu naniiai 



guiia 



1988 1989 



1988 



1989 



Sorex spp.^ 



INS 









Beaver pond 





7.0 3.7 



OA Q 



ion 



Adjacent 





.2 



.o 



u 



Sorex palustris 



INS 









Beaver pond 





.2 .2 



ft 



ft 



Adjacent 





.2 .3 



.o 



1 9 



1 ,£, 



Thomomys talpoides 



HER 









Beaver pond 









n 



w 



A 

 w 



Adjacent 





.2 



6 



n 



Perognathus parvus 



GRA 









Beaver pond 













n 

 \j 



Adjacent 





.2 



.6 





Peromyscus maniculatus 



OMN 









Beaver pond 





1.3 



A 7 



n 



Adjacent 





2.7 1.3 



9.5 



4.7 



Microtus longicaudus 



HER 









Beaver pond 





.2 .2 



.6 



.6 



Adjacent 

















Microtus montanus 



HER 









Beaver pond 





5.7 6.7 



20.1 



23.7 



Adjacent 





1.5 1.8 



5.3 



6.5 



Zapus princeps 



OMN 









Beaver pond 





.3 .2 



1.2 



.6 



Adjacent 

















Total trapped (n/ha) 











Beaver pond 







52.1 



38.5 



Adjacent 







17.2 



12.4 



Standing crop biomass (g/ha) 









Beaver pond 







819 



773 



Adjacent 







304 



283 



Species richness (n) 











Beaver pond 







6 



5 



Adjacent 







6 



3 



Species diversity^ (1/Ip/^) 

 Beaver pond 2.59 2.02 



Adjacent 2.47 2.33 



'After Martin and others (1951). INS = insectivore, HER = herbivore, GRA = granivore. OMN = omnivore. 

 ^Identification not confirmed; most appeared to be vagrant shrews (Sorex vagrans). 

 'After Hill (1973). Here p, is tfie proportional abundance of ttie n species in a sample. 



(Verts and Kirkland 1988), was caught at a single 

 location in the sagebrush/upland community type 

 where giant wildrye {Elymus cinereus) was codomi- 

 nant with scattered sagebrush and rabbitbrush 

 plants. Only a few individuals of the long-tailed 

 vole and western jumping mouse were trapped, and 

 those only in the beaver pond habitat. They were 

 caught in dense stands of grasses and sedges 

 beneath a willow overstory. Mounds of the northern 

 pocket gopher were evident throughout the area. 



but only one gopher was caught. Mink (Mustela 

 vison) and muskrats (Ondatra zibethicus) were 

 occasionally observed in or near the beaver pond. 



Four foraging guilds were represented among the 

 small mammals trapped at Summit Creek (table 1). 

 Together, herbivores and insectivores accounted for 

 almost 82 percent of the total small mammal com- 

 munity. The large majority of these — ^montane 

 voles, shrews, and long-tailed voles — were found in 

 the beaver pond ecosystem. Most of the omnivores 



3 



