In the spring, the Refuge’s woodlands are visited by Bullock’s orioles, warblers, finches, and other migrating songbirds. Among the open grasslands, western meadowlarks and kingbirds are plentiful, and mountain bluebirds race through on their way to the foothills west of Denver. Cinnamon-colored bison calves frolic around their mothers. Great blue herons, American avocets, and snowy egrets wade in the shallows around ponds and lakes. Swainson’s hawks, lark buntings, and yellow-headed blackbirds make their annual appearance. Prairie dog pups venture out of their burrows, fawns emerge from locust thickets, and loud begging calls of black-billed magpie chicks come from their enormous stick nests.