Like a bison shaking off a dust bath, Yellowstone is suddenly, energetically shedding the long winter. Days are longer, roads are opening, white spring beauty flowers will soon be blooming park-wide, and migrating birds-mountain bluebirds, red-winged blackbirds, sandhill cranes, and ospreys-are returning. Grizzly bear tracks have been spotted on Mary Mountain. Closures are in effect at key Bear Management Areas including Blacktail, Firehole, Gneiss Creek, Antelope, and Mary Mountain trails. And bison, which have wandered widely both inside and outside the park, are regrouping in the Lamar and Hayden valleys in preparation for birthing season at April's end.
 
Human activity is picking up, too. Through April 15, Yellowstone hosts spring cycling days. The road from West Yellowstone to Mammoth Hot Springs is open only to bicyclists, roller-bladers, and joggers as crews work to clear roadways. But the two-wheeling adventurers are advised to be ready for any kind of weather and road condition (including ice and debris), and watch out for road crews and plows. They should also carry their own food, water, and bear spray as no park services are open yet. Full details on cycling season are at www.nps.gov/yell/planyourvisit/springbike.htm.
 
On April 15, the West Entrance opens to motorized traffic, along with roadways between Madison and Old Faithful, Madison and Mammoth Hot Springs, and Norris and Canyon. The Old Faithful Visitor Education Center, which marked its grand opening last August, also opens that day. The next day, the National Park Service celebrates National Parks Week with free admission through April 24. Updated Yellowstone road information is available 24 hours a day by calling 307-344-2117.