Post a Question

These birds do appear (heavily streaked below and no real color on the head or throat) to be hatch-year Yellow-rumped Warblers. According to Dunn and Garrett's "Warblers" (Peterson Field Guide series), juveniles of both Yellow-rumped Warbler subspecies do not show yellow on their rumps until they go through their first prebasic molt. They describe the rump on juvs. as being "dull whitish with dusky streaks." At least one of these birds (the one with yellow down the middle of its throat) has already commenced its prebasic molt, which will result in a "first winter" plumage. Most Passerines (songbirds) will molt out of their juvenile plumage (first complete feather set) before they migrate in the Fall. Yellow-rumpeds are pretty hardy as warblers go, with many wintering in the mid-latitudes. They tend to migrate later than most other warblers, with the most noticeable push typically occurring no earlier than late September. Interestingly, most of the local breeders (subspecies "auduboni" or Audubon's Warbler) move out in Fall and during the winter season they are replaced by the more northerly and easterly breeding subspecies ("coronata" or "Myrtle Warbler), which predominates Nov-March. Great question Dawn, as it provided me with the opportunity to learn something new.