The species comprises two distinct subspecies that may merit specific status.
"Yellow palm warbler" or "eastern palm warbler" (S. p. hypochrysea) of the eastern third of the breeding range has brownish-olive upper parts and thoroughly yellow underparts with bold rufous breast and flank streaking. It migrates later in the fall than its western counterpart.
"Brown palm warbler" or "western palm warbler" (S. p. palmarum) inhabits the remaining western two-thirds of the breeding range. It has much less yellow below, with less colorful streaking, and cold grayish-brown upper parts.
These birds migrate to the southeastern United States, the Yucatán Peninsula, islands of the Caribbean, and eastern Nicaragua south to Panama to winter. They are one of the earlier migrants to return to their breeding grounds in the spring, often completing their migration almost two months before most other warblers.
Palm warbler has been recorded as a vagrant to Iceland.
Palm warbler nests take the form of an open cup, usually situated on or near the ground in an open area.
Palm warblers forage on the ground much more than other warblers, sometimes flying to catch insects. These birds mainly eat insects and berries. Their constant tail bobbing is an identifying characteristic. Kirtland's, prairie, and palm warblers are the only Setophaga species that incessantly bob their tails.
The song of this bird is a monotonous buzzy trill. The call is a sharp chek.
- BirdLife International (2012). "Dendroica palmarum". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- "Palm Warbler". All About Birds. Cornell Laboratory of Ornithology. Retrieved 2008-10-12.
- Þráinsson, Gunnlaugur (1997) Palm Warbler and Cerulean Warbler in Iceland - new to the Western Palearctic Birding World 10(10): 392-393
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