2ISSF, Western and Yellow (and yellow is really, really yellow). Some overlap, but yellow mostly eastern third of US and western is widespread. Plumage varies, with breeding (MAR-AUG) yellower on breast and browner on cap while non-breeding (SEP-FEB) is often duller. Yellow rump persists in both. Yellow subspecies is yellower in breeding and duller in non-breeding. M/F similar.