“By late summer,” Griffith explains, “plants have matured and dried so that they no longer provide adequate moisture to sustain the deer in this landscape that offers them no free water. Following about 12 days of warm nights and hot days in late July, the deer migrate from 5 to 10 miles north to the Pioneer Mountains. There they find free-flowing creeks and the cool, moist shade of aspen and Douglas-fir groves and wait out summer’s worst heat and dryness. Early fall rains trigger the deer’s return to the park’s wilderness from this oasis in late September to feed on the nutritious bitterbrush until November snowfalls usher them back to their winter range.”
The pristine and high-quality forage of the Craters of the Moon Wilderness Area, historically nearly untouched by domestic livestock grazing, has inspired this migratory strategy for evading drought. In effect, the mule deer make use of a dual summer range, a behavioral modification unknown elsewhere for their species.
“Their late summer and fall adaptations simply complete the mule deer’s yearlong strategy for coping with the limits that this volcanic landscape imposes on them,” Griffith explains.
Taking a walk in the park on a mid-summer afternoon gives you a good opportunity to experience the influence of wind, heat, and lack of moisture. The park’s winds are particularly striking. The lava that has flowed out of the Great Rift has built up and raised the land surface in the park to a higher elevation than its surroundings so that it intercepts the prevailing southwesterly winds. Afternoon winds usually die down in the evening. As part of the dynamics of temperature and moisture that determine mule deer behavior, this daily wind cycle helps explain why they are more active at night than are mule deer elsewhere. These deer do not move around as much as mule deer in less ecologically trying areas. They have adapted behaviors to conserve energy and moisture in this environmentally stressful landscape.
Early mornings may find park rangers climbing up a cinder cone to count the deer, continuing the collection of data that Brad Griffith set in motion with his three-year study. The rangers still conduct spring and late summer censuses: over a recent three-year period the deer populations averaged about 420 animals. Another several years of collecting will give the National Park Service a body of data on the mule deer that is available nowhere else.
The uniqueness of this data about the park’s mule deer population would surely please the booster aspect of Robert Limbert’s personality. Likewise, the research challenges involved in obtaining it would appeal to his explorer self. History has justified Limbert on both counts. Publicity arising from his explorations led to creation of the national monument. Furthermore, that publicity put forth a rather heady claim that history has also unequivocally borne out: “Although almost totally unknown at present,” Limbert prophesied in 1924, “this section is destined some day to attract tourists from all America....”
Every year tens of thousands of travelers fulfill Robert Limbert’s prophecy of more than a half-century ago.
Part 2
From Moonscape to Landscape
