This is an interesting thread. Brandon is correct in answering David Leatherman's question, of "what's next?"
with the reply, "pretty much anything."
And there are specific, evidence-based answers to David's intriguing question:
First, Pine Warbler is not our only "winter warbler."
That status also applies to Cape May Warbler, with multiple "after Halloween" records.
It has been found at bird feeders in winter and visited both Jane Axtell's and Alex Cruz's feeders daily for a week or more.
(Keep that suet feeder filled, and find a source for overnight Fed-Ex delivery of meal worms).
Another winter warbler is Painted Redstart. Two of Colorado's first four Painted Redstart records were
from late fall:
Oct 25 through November 8 in El Paso County and
November 16 through 22, Larimer County.
And I recall, possibly correctly, that Peter Gent explored a southeast Colorado woodlot
in December, a long time ago, and the only bird present was a hardy Connecticut Warbler.
This ancient information is from "Bob and Bob," where else?
Joe Roller,
Denver