American Herring Gull (smithsonianus)
(last update: October 30, 2015)
American Herring Gull (smithsonianus) 3cy, February 07 2005, St. John's, Newfoundland, Canada. Picture: Jeff Poklen.
See this website by Jeff, showing West coast birds mostly.
East coast 3cy bird, showing bold 'smoky' winter streaking concentrated in the hindneck, but also on flanks and underparts. Obvious greater covert bar. Note replaced upper tertials and greater covert #2(from partrial autumn moult in 2cy), and note pale iris.
From a European point of view: illustrative example of probably 'the most rewarding' type of bird to look for!