Many birds have different colors for winter than for summer as this helps them hide better in those months - adopting the colors fairly close to their winter or summer garb.
My favorites are the Wild Canaries or American Goldfinches. Seeing these in the country side - usually in large flocks are absolutely beautiful. I can't help but imaginethe settlers on a beautiful spring day watching these gorgeous birds flying through the countryside.
It's fun to watch birds change from their drab winter garb to their summertime bright colors, and even more fun to watch it happen in one sitting (with different birds - - hopefully). In south Texas, they are turning in March.