This beautiful little warbler is 4-5” in length and has a yellow face, breast and belly. The back and tail are olive green; the wings are a darker olive color. The male has a distinctive black cap which is reduced or absent in the female. Wilson’s warblers nest in brushy forest edges and mountain meadows, typically in alder or willow thickets near streams. The breeding range extends across Canada and up through Alaska and down into the northwestern Cascades, Sierras, and Rocky mountains of Colorado. They winter in Mexico and Central America, and in the U.S. along the Gulf Coast.
But during spring and fall migration, these warblers may be seen in New Mexico and other states, foraging among sunflower patches and other brushy areas and forest edges, and even in drier scrubland habitats, actively hopping from the ground to low vegetation. They eat insects and other invertebrates, sometimes snatching them out of the air. They seldom remain in place for long, constantly flitting about as they hunt.
Nests are built on the ground or at the base of shrubs, being made of dead leaves, moss, and grass. Chicks hatch after about two weeks and are altricial, or naked and not fully feathered. They will grow quickly and fledge after another two weeks. Adults will continue to feed fledged young for several weeks after they leave the nest. Brown-headed cowbirds sometimes lay eggs in Wilson’s warblers’ nests and the adult warblers unknowingly raise the cowbird young as their own, an example of nest parasitism, which often has negative outcomes for the host bird’s brood.
The Audubon Society reports that the Wilson’s warbler population is stable at this time. They predict that continued global warming will result in a range shift upwards farther into Canada and Alaska with habitat losses across central Canada and down into the U.S. rockies and western mountains. The birds photographed here were seen in September during their fall migration in the Cibola National Forest and along old Highway 41 in Moriarty.