When Millie the marmot goes into hibernation, her best friend Sunny the squirrel gets very sad. In the autumn, young squirrel Sunny rushes outside to play in the burnished leaves with her best friend Millie. When Millie explains that soon she’ll go away until spring, Sunny is heartbroken; Mama tries to comfort her but isn’t much help. Lonely Sunny fills an empty winter day making a snowman, and it delights her by coming to life. “My name is Fred,” he says. They make up songs and rhymes and jokes together all winter long. When Fred melts, Sunny is sad again, but with the spring her beloved Millie returns. The duo makes plans for fun in spring and summer and autumn. Devos adds an extra layer of humor with cute outfits for the animal heroines. Her clean watercolor illustrations match Elschner’s straightforward story about childhood feelings and the passing of the seasons. (Picture book. 3-6)