HI:
I saw this article in the latest WESTERN BIRDS:

Specimen record of a Long-billed Murrelet from Eastern Washington, with
notes on plumage and morphometric differences between long-billed and
marbled murrelets. Christopher Thompson, Kevin J. Pullen, Richard E.
Johnson, and Eric Cummins. Page 157-168.

The main identification point: "Contrary to many recent publications
stating that long-billed and marbled murrelets have white and brown under
wing coverts, respectively, we confirmed that both species typically have
white under wing coverts prior to definitive prebasic molt and brown under
wing coverts after this molt."

--
Ian Paulsen
Bainbridge Island, WA, USA
A.K.A.: "Birdbooker"
"Rallidae all the way!"