As winter settles over Grand Teton National Park, the season brings both opportunities for outdoor recreation and challenges for the park's wildlife. Wildlife biologists urge visitors to be mindful of the animal’s need for space during this critical time of year. Please respect winter closures to minimize your disturbance, and visitors should maintain at least one hundred yards of distance from bears and wolves and twenty five yards from all other wildlife. By giving animals the space they need, visitors can safely enjoy observing wildlife while helping protect the creature's energy reserves during the harsh winter months.
● The bighorn sheep rutting season has begun. After putting on weight during summer grazing, these animals now face the challenge of winter survival, relying on fat reserves built during the warmer months. Last winter, biologists took body fat measurements on park bighorn and found that they entered the winter with high fat reserves. However, given that these sheep experience more severe winter conditions than most populations, it might be an essential adaptation for their survival.
● Fall-spawning mountain whitefish head to deeper water as their eggs incubate for the next several months. With colder water temperatures, fish activity slows, and their energy needs diminish, allowing them to conserve energy during the winter months.
● Adult bald eagles with nesting territories in the park and valley remain year-round. As fish become scarce beneath the ice, these eagles increase their predation on waterfowl to sustain themselves through the winter.
● Most black bears entered their winter dens by the end of October, while grizzly bears typically begin their hibernation in November. A small number of grizzly bears have learned how to put on additional fat during late fall/early winter and could remain out and about for another few weeks.
● Many of the mule deer that undertake long-distance migrations have left the park and are en route or settled into their winter ranges. Because of the relatively mild weather and low snow levels this fall, mule deer that migrate shorter distances have yet to begin their migrations.
● Chipmunks that were active in October have begun spending their time resting in their burrows. Chipmunks do not hibernate or put on excess fat in the fall. Instead, they survive the winter by entering torpor, a state of decreased physiological activity usually marked by a reduced body temperature and metabolic rate. They rest for long stretches of time, waking to eat food they cached in the burrow.
● Rough-legged hawks, often prominent on fence posts and power poles, have returned from their Arctic nesting grounds to winter in the valley.
● Trumpeter swans are the heaviest flying bird in North America, with adults often weighing over 20 pounds. Trumpeters migrate from around the region and habitats further north to spend their winters on open water in the valley in larger numbers than seen in summer.
● Elk have descended from the high country awaiting heavier snows to push them further south onto the National Elk Refuge where most will remain for the winter.
● Long-tailed weasels and snowshoe hares have shed their summer brown coats for a camouflaging winter white. The weasels maintain the distinctive black tip on their tail to help distract potential predators.
● Beaver activity is strongly influenced by ice conditions as they continue to store willow and other cuttings under the ice to ensure enough food supply for the long winter.
● Wolf pups largely confined to den and rendezvous sites since birth are now traveling with the rest of the pack, learning how to hunt and survive in the wild.