In comparing photos of American Goldfinches and Common Loons taken in summer and winter, I am struck with the vibrancy of their colors in summer and the almost "dressed down" look in winter.
The rich yellow hue dominates the Goldfinch's breast and back in summer, along with a black cap. The black and white wings and tail offer a sharp contrast to the yellow. In winter, the black cap is missing and the yellow is faded to a dull brown on the back with a faded whitened yellow and/or brown tones on the breast. Wings and tail feathers look similar in both seasons.
In summer, the Common Loon looks dapper with its black and white pinstripes separated by an emerald green band. The throat has a black and white curve. The red eye is striking. In winter, dulled browns and white dominate and the eye doesn't seem to be as striking in color.
What surprised me was that photos of the winter Loon did not identify sex, usually indicating "Unknown."