Spring is a busy time at the refuge. Wildlife, dormant for the winter, begins to wake. Black bears rouse and their cubs, which were born over the winter, venture out of the den for the first time. The lively, little chipmunks began their never ending search for food. Virtually frogcicles during the winter, wood frogs and spring peepers thaw and begin their mating songs. Old friends, like Canada geese, common loons, and trumpeter swans return from their wintering grounds to raise their families, filling the air with their calls. Visitors at this time may be lucky enough to see the mating dance of the sandhill cranes or sharp-tailed grouse. Late May is a great time for birders to enjoy spotting warblers and listen for the calls of rails.