I just happened to click when these two gulls took off from the top of the dam to the spillway. The bird with more brown on its wings is a First Winter Ring-billed gull. The other gull is a 2nd Winter Ring-billed gull.
First Winter and Second Winter Ring-billed Gull (Larus delawarensis)
First Winter Ringbilled Gullfirst winterlarus delawarensisgullwhite rock lakedallas texasringbilled gullringbilledaquatic birdaquaticwater fowlwinter plumagespillwayupper spillwayflood watersrushing waterwaterfallflyingwingssparklestop of damdamsecond year ring billed gullsecond winter Ringbilled gullKala, from