Cagwell 1949 Larus delawarensis Aug 13,16,17 - Big Lagoon, Humboldt Co., Calif. Several of the immature gulls on the lagoon (up to 10 or so in total number) were probably of this species. One collected (but not saved) on Aug. 13 definitely was this species -- a bird going into 2nd year plumage, minus a tail except for pin feathers.