Pine Warblers nest across most of the eastern United States, as well as parts of southeastern Canada, almost exclusively in forests dominated by pines.  They’re fairly picky about their habitat – not only do they require pines, they strongly prefer certain types of pines.  In Pennsylvania, they like red pine, pitch pine, and Virginia pine.  You don’t usually find them using the more common eastern white pine.  The Pine Warbler nesting range in Pennsylvania is mostly in the Appalachian Mountains.  Their breeding population in the state is relatively small, with only about 90,000 birds.  For comparison, five species of warblers in the state have breeding populations of over one million birds each (Ovenbird, Common Yellowthroat, American Redstart, Yellow Warbler, and Chestnut-sided Warbler).

Unlike most of North America’s wood warblers, Pine Warblers don’t migrate to the Tropics during the winter.  In winter, they live across the southeastern United States, as far north as southeastern Virginia and southern Delaware.  A very small number are observed in Pennsylvania each winter.

Another Pine Warbler oddity, as compared to other warblers, is their ability to digest seeds.  Almost all warblers eat mostly insects and spiders, often supplemented by fruit during migration.  Pine Warblers are primarily insectivorous during the summer, but as winter approaches their digestive system changes to allow them to eat seeds.  That trait likely evolved to allow them to eat pine seeds, but it also means that Pine Warblers are the most likely warbler to visit your bird feeders.  They’ll eat sunflower seeds, white proso millet, peanuts, and suet.  Their favorite is Bark Butter.