Found by Tom Perlman in the Wildflower Meadow of Central Park on 23 September 2017. Very actively feeding. No tail-pumping observed.
Two sets of photos, taken ~1hr 15min apart, under different lighting conditions. No color correction applied.

I created an ID poll for this bird on my Twitter page, if you'd like to participate. You can only vote once, and you cannot change your vote. Click the Twitter link on this site to reach the poll and related discussions.
Your vote remains anonymous. I cannot tell who voted, or how you voted, unless you choose to tell me ;-)

Update: The poll is closed, and the correct answer can be found on my Twitter page. You can also access my eBird checklist to see the answer:
http://ebird.org/ebird/view/checklist/S39396644