The past two blogs have explored winged migration--but throughout Idaho, it's also the season for a hoofed migration.
Each year, mule deer--and elk, moose and pronghorn--migrate from the mountains to the valleys to escape heavy snow. In the low-elevation sagebrush, they find better weather, and, at least in the past, better nutrition and less stressful living conditions.
Idaho is blessed with large tracts of public lands which support animals that need a lot of space to thrive, like mule deer and elk. But many of those public lands are not viable for the animals in the winter and early spring.
Yellowstone National Park, for instance, is known as a haven for wildlife--but its high elevations make it an inhospitable place in the winter. And so big game moves out. Five of the twelve longest large mammal migration routes on earth are located in the Greater Yellowstone area.
And what do wildlife need when they get to their winter range? Good nutrition, for one thing. Sagebrush is very important to the diets of deer and pronghorn, comprising as much as 90% of winter nutrition in some areas. Bitterbrush (pictured above) and similar shrubs complement this diet nicely. (Some ecologists call bitterbrush "deer candy").
Unfortunately, cheatgrass and other non-native weeds start a fire cycle that eventually eliminates these shrubs. Deer will eat green cheat grass, but it's not as nutritious and often provides very little cover. Some deer herds have disappeared when the sagebrush vanishes, as in the case of the foothills around Twin Falls.