18 



COMMON MAMMALS OK WKSTKHN MONTANA. 















'*9y? \ ^-_s 

















• 



Fi<;. 8. — "Surface set," made with "Jump" steel trap. 



Surface sots are made by sinking traps (lush with the surface of 

 (lie ground near squirrel burrows and sprinkling oats or other bail 



in a circle just outside of 

 the jaws. (Figs. 8 and 

 0). The advantages of 

 this method of setting 

 are that fewer traps are 

 required to cover a given 

 number of burrows and 

 that enemies of squirrels 

 using the burrows are 

 not endangered. The 

 disadvantages are that 

 the surface sets require 

 more time to make, that 

 they occasionally catch 

 meadow larks, quail, or 

 other valuable birds, and 

 that they are not always 

 cllVctive whein green vegetation is abundant. "Jump" traps with 

 their large pans are better suited to surface sets than are the 

 small-panned outside-spring traps, for the animals are likely to walk 

 around the latter sort 

 of traps instead of 

 stepping into them. 

 Sometimes clods of 

 earth placed on oppo- 

 site sides of the traps 

 serve to guide the 

 squirrels into them. 



The most effective 

 trapping can be done 

 by using a combina- 

 tion of hole and sur- 

 face sets made as cir- 

 cumstances suggest, 

 and with jump traps, 

 perhaps one-third of 

 which are Xo. 1 and 

 the rest No. 0. In this 

 case the No. 1 trap- 

 should be reserved for 

 the surface sets and the smaller size used in the holes. As a rule 

 waste land, where burrows are numerous, can be trapped to the best 

 advantage with surface sets, while hole sets are more effective in 



484 



Fig. 9.- 



-Two Columbian ground squirrels caught in 

 "surface-set" jump trap. 



