I also did NOT see the Sabine's Gull from the boat launch off of East Lake Sammamish Parkway.
I was there on Sunday, 9/21/14, from 11am to 12:30pm, then after a lunch break I returned to the boat launch for another session of not seeing the Sabine's from 1pm to 2:15pm.

Joe Sweeney
NE Seattle
sweeneyfit at mac dot com