New Hampshire

Help Us Learn More About Palm Warbler Migration, by Hector Galbraith

Two sub-species of Palm Warbler are known to occur on migration in New England, the Yellow or Eastern Palm, and the Western or gray palm. In the spring most earlier Palm Warblers are Yellow, while Westerns seem to pass through the west of the region later and in smaller numbers.

Right now, for example, in the Connecticut River Valley in Western New Hampshire many Yellow have already passed through and there are now mixed parties of both sub-species. On the coast, most birds seem to be Yellow, and Westerns may be rare. In the fall, the situation seems to flip with Westerns being the normal coastal race and Yellows occurring further inland.

There is a lot that we do not yet understand about the migration of the sub-species of Palm Warbler through our region. This is partly because birders do not typically report the sub-species of birds that they find, calling them simply Palm Warblers. Nevertheless, separation of the sub-species is usually not too difficult; both Sibley and National Geographic guide have good illustrations.

So, a plea: please record your sub-species in eBird. The initial list of species that you see will not show the two sub-species. To find them, simply click the “add a species” option and type in Palm Warbler. You will then be offered the option of Palm Warbler with no sub-species, the Yellow (eastern) sub-species, or the Western sub-species and you can record your birds accordingly. Simple!