December is the twelfth and last month of the year according to the Gregorian calendar. This is used used in almost all the world today. It was the tenth month in the early Roman calendar. It became the twelfth month in a later Roman calendar. Until 46 B.C., December only had 29 days. But the Roman statesman Julius Caesar added two days to December, which made it 31 days. In the northern half of the world, Winter begins in December. Winter does not begin until December 21 or 22, and most of December is usually warmer than other winter months. The latter part of December has long been a holiday season. Christians celebrate Christmas Day, as the birthday of Jesus Christ. In the Northern Hemisphere, most birds have gone to warmer climates. But many animals are active. Mink, ermine, beavers, and foxes grow beautiful coats of fur. Nature finishes preparing for the long winter ahead. Many people make feeding places for birds and squirrels.