I took these pictures along Lands End Trail in San Francisco on May 2. White-crowned Sparrows were easily the most numerous sparrow along the trail. The one in the pictures above was building a nest in the tall grass very near the trail. I watched as it would fly a short distance away to find some dried grass, sometimes yanking and shaking it to free it from the ground or untangle it from the brush.
I thought I may have found a new life bird. The mixture of brown and black on its crown was not something that I had seen before, but when I took a closer look on my computer I am pretty confident that this is a young White-crowned that is transitioning from the brown striped crown of a juvenile to the black and white crown of an adult.