Many mammals shed summer coats and develop winter ones; birds (like cardinals) also develop winter feathers. There are places (like caves) animals can go to in cold weather. Animals also hibernate, or sleep until spring. Speaking of seasonal changes, in the Northern Hemisphere, there is a "Northern" winter (Earth is "tipped away" from the Sun). In the Northern Hemisphere there is also a "Northern" summer (Earth is "tipped towards" the Sun).
Northern places get more hours of sunlight in summer, as well as fewer hours of nighttime (there are only 9 hours of sunlight in winter). Not all days of sunlight are the same (they don't have the same amount of daylight). Certain seasons have more (or less) sunlight than others.