First, Michael, please tell me that pix #1554, 1557, etc. is not Mendenhall
The mystery gull looks good to me for Thayer's, particularly the wingtip
pattern and extended white on P1.
The amazing bird here is the mystery Alcidae spp. This does not look like
an Alcid to me at all. The head shape is almost petrel-like, and the bill
is startling as to both color and shape, almost like a tubenose. I would
love to hear someone else's comments.