Spring poses significant challenges for wildlife as they contend with depleted winter fat reserves and limited availability of new plant growth, which is often in its earliest stages and sparsely distributed. Consequently, conserving energy remains a critical priority during this transitional period.
● As of Monday, March 25, the Snake River Headwaters is recording snow water equivalents at 100% of median, compared to 117% in 2023, 79% in 2022, and 93% in 2021 for the same day. There are seventeen days until the median peak date of April 11.
● The heavy wet snows that came during the first of March prompted bison to move south in the park for better forage opportunities. Traditionally bison move from Elk Ranch Flats to Antelope Flats as snow cover deepens and decreases their ability to sweep aside the snow to access food. They often use plowed road corridors as travel routes instead of expending energy wading through deep snow. This creates a substantial road hazard.
● The first grizzly bear in Grand Teton/John D. Rockefeller, Jr. Memorial Parkway was observed on March 26th. Park scientists believe that the late season snows contributed to the later than usual first sighting. The first grizzly observed in Yellowstone was on March 3 this year. Adult male bears are the first out of their dens, with more than half out and about by the end of March. Bears with new cubs are usually the last ones to emerge from their dens in late April or early May.
● As the snowpack recedes on the valley floor and rivers start to open up, some bald eagles are already sitting on their nests. Many other wildlife species including ravens, river otters, golden eagles, great-horned owls, and Canada geese have begun their courtship and breeding activities.
● The first migrating birds of the season are beginning to arrive including western bluebirds, red wing blackbirds, red-tailed hawks, northern flickers, and robins. Soon to follow will be sandhill cranes, osprey, and other migratory birds.
● In the weeks ahead, snowshoe hares and long-tailed weasels will start shedding their white winter fur, preparing to blend in with the varied hues of the seasons ahead.
● Elk have wintered in typical areas this year, but elk on the refuge will start to drift north as they follow the receding snow and vegetation green-up. Bull (male) elk grow a new set of antlers annually. Decreased daylight lowers testosterone, which causes the connection between antler and skull to weaken and the antlers to fall off. Elk generally shed their antlers between March and April and begin growing a new set shortly thereafter. Larger bulls drop their antlers earlier than smaller bulls, especially spikes (yearling bulls) who may retain their antlers into May. Antler collection in the park is illegal as the shed antlers are an important source of nutrients for rodents like mice, chipmunks, and squirrels, as well as porcupines and other animals that gnaw on shed antlers.
● Wolverines produce 1-2 kits that are born from mid-February through March. Females dig dens in high, remote alpine basins where the snowpack persists late into the spring. She raises the kits alone and stashes them when she goes out on forays for food. If undisturbed, the female and kits may use the natal den until May. Wolverines are primarily scavengers depending almost exclusively on carrion in winter and early spring. They possess an upper molar in the back of the mouth that is rotated 90 degrees towards the inside of the mouth. The molar allows wolverines to tear off meat from prey or carrion frozen solid.
● Male greater sage-grouse will begin strutting on open areas of the sagebrush called leks to attract a mate in late March or early April. Each spring, at dawn, the males puff their chests and fan their starburst tails to strut. They inflate bulbous yellow air sacs and thrust with their heads to produce weird pops and whistles. In preparation for this display, male greater sage-grouse can gulp and hold a gallon of air in a pouch of their esophagus. By squeezing it out with force, they begin their display. Over the harsh winter, sage-grouse actually manage to gain weight and strength in preparation for the breeding season by feeding on the leaves of sagebrush. They get water from feeding on snow.
