This image was taken through many branches and foliage. Light was dim (you can't tell in this photo) so I used flash and shot it in Manual Mode (usually do when light is low).

According to someone going by the username of Brushyrun at birdforum.net: "They start out this predominantly grey and white coloration, with just the hint of yellow edging on wing feathers. Coloring will change a bit over the next month or two, to include slightly more yellow--but Yellow Warbler immatures will continue to carry much of that brownish grey plummage for the first year."