Spring Deer Surveys Completed

Fish and Game biologists recently finished surveying deer populations in several areas of the Salmon region. Parts of hunting units 21, 27, 29, 30, 30A, and 36B were surveyed by helicopter to get population estimates for deer herds in those units. In general, deer populations were found to be stable or slightly increasing. This was a bit of a surprise given the low numbers of fawns seen in December. However, the relatively mild winter weather coupled with snow-free range in many areas gave the deer the boost they needed to survive the winter. The exception was in Unit 36B where deer numbers are continuing to decline. Since deer in that unit had still not moved off winter range at the time of the surveys, biologists feel that they got accurate counts in this unit and that the low numbers were not due to factors such as weather or survey timing. Why are the Salmon region deer herds not increasing more quickly after two mild winters and no harvest of does? Biologists suspect the lack of deer population response is habitat-related. The first clue is in antler growth rates. At any given age, an average Salmon region buck has smaller antlers than bucks of the same age in other parts of southern Idaho. The most likely cause of small antlers is nutritional deficiency. The second and perhaps more important clue is fawn size which also indicates nutritional deficiency. December fawn weights from the Salmon region are typically the lightest in southern Idaho. Mule deer fawn weight entering the winter bears directly on the fawn's chances of surviving the winter. The lighter and smaller the fawn, the more likely it will die during any winter except the most mild. On the other hand, large robust fawns will typically survive all but the harshest winters. Fawn survival leads directly into changes in total deer numbers. Since the fawns produced in the Salmon region are small and have poor survivability, the deer herds become stagnant or begin to decline.