Great pics RayneForhest! It's amazing how dramatic the change is! My young black females will go from cellophane to coal black within seconds, it makes me wonder lol.
All animals will change behavior (and therefore color depending on the species) throughout the year... from what I've read it has to do with barometric/atmospheric pressure (lower during the winter=winter blues and higher during the summer=more active). During the summer, when they are feeling better, they are likely to show their true colors.