Loud echolocation is the norm among open-air insectivores; some bats emit calls above 120 decibels at the mouth. That works against most prey but alerts eared moths, which drop, loop or dive when they detect a call.
Corynorhinus townsendii belongs to a group informally called whispering bats. Its calls are of low intensity, which shortens detection range considerably but keeps the bat below the threshold at which a moth's tympanal organ triggers evasion. The very large pinnae compensate on the receiving side, gathering the weak returning echo, and probably help with passive listening for prey-generated sounds as well. Moths dominate the diet.
The more pressing conservation fact concerns roosting rather than hunting. This species is unusually intolerant of disturbance: hibernating and maternity colonies will abandon a cave or mine after repeated visits, and gates or closures at abandoned mines are a common management response. Several subspecies have been treated as at risk in parts of the range even though the species overall is assessed as Least Concern.