Small songbirds face big challenges in winter—most of all, keeping warm. Consider the black-capped chickadee, one of the most common North American wintering birds. These lilliputians lose heat quickly because their surface area is large for their mass; they weigh about as much as a dozen paperclips (a third of an ounce) but stretch 5.5 inches long. Meeting that challenge means ramping up the number of hours they devote to feeding and seeking out foods rich in antioxidants and fats. At night chickadees cram themselves into tiny cavities and shiver, burning the day’s fuel to keep from freezing. You can help chickadees and many other birds by planting native shrubs and trees yielding the right berries. Choose plants that are native to your region (see plant list) because birds (like the Bohemian waxwing, above) recognize them, and thus spend less energy foraging. Make sure to pick types that will thrive in your particular microclimate—a yard’s soil and environment. A plant...