The Northern Parula is one of the smallest of the warblers. It's head and back are bluish gray, and it's chin and chest are yellow. The eyes have a partial white ring. The male Northern Parula has an orange patch at the top of the chest and a darkish band between chest and chin.
The male Northern Parula in this photo was difficult to photograph. It mostly stayed in the foliage of the trees, hopping from branch to branch, likely looking for insects. It didn't stick around long, giving me the opportunity to take only a few photos, most in which the bird is obscured or blurred.