Something New?

Here's a fascinating photograph taken here, by BirdCam in recent days.  I have two images from different angles, but neither is a very good photo.  My immediate reaction was: maybe this is something new.  The head and tail are arrestingly yellow.  Time to pull out the field guides and puzzle it out.  The bill is definitely in the warbler class, as is the basic color.  This bird is not at all colored like our winter Yellow Rumped Warblers, nor is its coloration typical of perennial Pine Warblers.  So what does that mean?  I live in the world of plausible species...so I am ruling out the other warblers.  Something else?  Very possibly: But I don't have near enough information and don't want to get caught up in speculation.  I'm not calling this yet, but I will definitely be scrutinizing my photos.  But what a score a new species would be!