The Palm Warbler is our earliest arriving warbler in most years. It song is a musical trill much like Chipping Sparrow and Dark-eyed Junco. I often confuse the songs early in the year so when I first hear one I check it out with my binoculars.
The breeding plumage of the male is stunning. Interestingly in my experience although I hear it singing early in the season it abruptly goes silent as it begins nesting in May.