Many birds molt in the summer after their breeding season is over. New feathers grow in and it helps them when they migrate the many miles to their wintering grounds.
Some birds change so much they are hard to identify. Like the sparrow in the above photo.
The Chipping Sparrow is a common backyard bird. In the fall they lose the rufous cap, but they do retain the dark line that runs through their eye.
In this photo, the bird on the right is the ubiquitous bird that occurs in our forests of Voyageur country, the White-throated Sparrow. The White-throated Sparrow does not change much when going into winter, but the juveniles are different and hard to i.d.
The bird on the left is a White-crowned Sparrow, and it’s a juvenile or first winter bird. It is very different than the adult. The White-crowned Sparrow breeds further north in Canada and only migrates through our area.