There was a second-cycle LESSER BLACK-BACKED GULL at the Yolo County Central Landfill Pond late this morning.
You'll notice the very slender build (long wings), dark tail, dark upperwing, pale head with a mostly-black bill with a yellow tip, and yellowish legs.
Here are some bleached-out photos I took with my phone through my scope:
Although 2 LBBGs were seen at this pond this past winter, it's already April and getting on the late side. According to eBird, this is the latest LBBG record for this part of the Central Valley. Personally, this is the third LBBG I've seen in California and they've all been at the exact same pond. In fact, this species has been annual at this pond since 2009.