Mule Deer
Brad Griffith could be called the mule deer man. In 1980, this wildlife researcher began a three-year study of the mule deer herd that summers in the park. The immediate concern was that the deer, protected inside the park, might be overpopulating their range and endangering their habitat. Griffith set out to find out just how the deer use the area, what their population level is, and how certain factors—production, mortality, and distribution—affect their population dynamics. The mule deer use the park April through November only, because winter brings snows too deep for the deer to find food here. The most striking finding of Griffith’s research is that the mule deer at Craters of the Moon—unlike mule deer studied elsewhere—have a dual summer range. Put simply, the mule deer have had to undergo behavior modification to live here. The deer move back into the southern park in mid-April, living in the protected wilderness area there. While in the wilderness area, the park’s deer routinely live up to nearly 10 miles from open water, getting their water from food, dew, fog, and temporary puddles. This area has higher quality forage for these deer than any other part of their annual range. The trade-off is that the wilderness area has almost no open water. When the moisture content of their forage decreases in summer, usually in July, the deer move up to the northern part of the park where there is open water. Their habits in the northern part of the park are unusual, too, Griffith says, because there the deer live in much closer quarters than other herds are known to tolerate on summer ranges. They live in this wildlife equivalent of an apartment complex until the fall rains come. Then they move back down to the wilderness area. The deer make this unusual summer migration, Griffith suggests, to avail themselves of the high quality forage in the southern park. “The park serves as an island of high quality habitat for mule deer,” he wrote in his report. It is now known the deer will leave the wilderness area for the northern park after 12 days with daytime highs above 80°F and nighttime lows above 50°F in summer. “We can’t really predict this,” Park Ranger Neil King says, “but the deer know when this is.” What is happening is that the percentage of water in their forage plants falls below what is necessary to sustain the deer with increasingly hot weather. As you would expect, does nursing two fawns leave a couple days earlier than does with only one fawn. The rate at which their fawns survive to the fall of the year is astonishing. “This is an incredibly productive herd,” Griffith says, “right up there with the highest fawn survival rate of any western mule deer herd.” Park rangers continue Griffith’s studies by taking deer census counts.
The Northern Shoshone regularly passed through the Craters of the Moon area on their annual summer migration from the Snake River to the Camas Prairie, west of the park. They took this journey to get out of the hot desert and into the cooler mountains. There they could gather root crops and hunt marmots, jackrabbits, porcupines, and ground squirrels. As they passed through today’s park, they left behind arrowheads, choppers, and scrapers and built stone circles that may have been used for ceremonial purposes. These artifacts and structures are evidence the Indians were temporary visitors to this vast volcanic landscape.