Palm Warbler

Bird of the Month: Palm Warbler

By Andy McCormick

PC: Constance Parry/Audubon Photography Awards (Palm Warbler)

PC: Constance Parry/Audubon Photography Awards (Palm Warbler)

Scientific Name: Setophaga palmarum

Length 5.5 in

Wingspan 8 in

Weight 0.36 oz

AOU Band code WPWA

The Palm Warbler is one of Washington’s “Winter Warblers.” In late fall and winter, with numbers varying considerably each year, Palm Warblers migrate south along the Pacific Coast through Washington, Oregon and California. In recent years Palm Warblers have been seen in Ocean Shores and on the Seattle campus of the University of Washington. They are an early spring and late fall migrant primarily because they are one of the two most northerly breeding warblers. The other is the Blackpoll Warbler. 

Our Western Subspecies
There are two distinguishable subspecies of Palm Warbler, which have separate migration routes and breeding grounds. The subspecies seen most often in Washington is the “Western” Palm Warbler (WPWA). The “Yellow” Palm Warbler (YPWA) is the eastern subspecies. This article will focus on the “Western” Palm Warbler.  

The “Western” subspecies must have been named from an eastern perspective. Despite its name, the “Western” Pine Warbler is rarely seen in the western United States. Nevertheless, it is the more wide-ranging of the two subspecies. In spring it migrates through the Central Flyway west of the Appalachian Mountains. It breeds from the Hudson Bay area west to the Yukon Territory. The Palm Warbler winters in the Southeastern United States and can be found around palm trees for which it was named (Holloway), but it almost never goes into a palm tree (Dunn and Garrett). It is only during fall migration that a few of these birds are seen in the Western United States.

In sphagnum bogs with scattered cedar, tamarack, and spruce trees, or in dry pine barrens of the boreal forest, the Palm Warbler builds a cup nest on the ground in grass or sphagnum moss (Kaufman).  Usually four to five brown-spotted, creamy white eggs are deposited. Incubation lasts about 12 days. The young are fed by both parents are fledge in another 12 days. After two more days the young are flying. Many breeding pairs have two broods per year (Kaufman). 

Telltale Tail Pumper
The Palm Warbler is generally easily identifiable. It stands out for its habit of continuous up and down tail pumping. The movement also attracts the eye to its bright yellow undertail coverts, which always contrast with its white or pale yellow belly (Dunn and Garrett). It is a rather plain, brownish streaked bird with a long white supercilium stripe over a black eyeline. Its “ground foraging habits and drab streaked plumage may recall sparrows or pipits” (Sibley).  

The population of Palm Warblers seems to be stable with some increased numbers in Christmas Bird Count data in Florida where many Palm Warblers winter. There are no specific conservation measures in place. However, there is some concern for the population as more of the peat bogs in the boreal forest are mined for fossil fuels.