In the picture above is a whitetail doe, Odocoileus virginianus, in a woodland clearing. This picture was taken in mid-September and shows the light brown pelage of spring and summer.
In the second picture, you see another whitetail doe whose pelage has transitioned to the greyish winter coloration. This picture was taken in early November of the same year and same locality. The deer, however, were different individuals.
Aside from the beauty of the scenes and the subjects, what can be learned here is that color transition in whitetails seems to happen within a fairly short time.