IDFG biologists collect various measurements on mule deer fawns such as; weight, chest girth, hind foot length, and body condition score. A radio collar is placed on the deer to provide animal locations and survival. Located within the radio collar is a mercury switch that causes the signal to speed up when the animal has been inactive for more than 4 hours, indicating that the deer has likely died. IDFG wildlife biologists then use the radio signal to locate the carcass and determine cause of mortality.