The Yolo Central Landfill and associated ponds have been productive lately and birders have found several interesting birds there in the past week. 

The gulls can be viewed while they are resting in flocks on and around the ponds surrounding the landfill. The most productive of these have been the three ponds west of County Road 104 (38.5978227, -121.6937934), two of which are viewable from the shoulder of that dirt road and one of which requires walking out a bit from the gap in the fence. The gulls shift between these ponds at different times of the day, but in my couple of visits I found that the western one has had consistent numbers in the mid-morning and the northern one getting lots by early afternoon. The main landfill pond is viewable from a gravel topped levee (38.5904584, -121.6802362) and gets very large flocks on the water and on the steep dirt berm on the NE part of the pond. I have noticed this area getting large numbers by early afternoon but fewer in the morning. There is also the nearby Davis WTP pond (38.5907396, -121.6696572) which has had large numbers of gulls occasionally but has been pretty overwhelmingly California Gulls every time I check. 

To watch the gulls here, a spotting scope is essential and even with one many of them are too far to identify. On warmer days, heat shimmer makes them very hard to observe past noon. 

Two Lesser Black-backed Gulls have been seen in the CR 104 ponds, an adult was found by Ethan Monk on 02/24/2022 (https://ebird.org/checklist/S103724872) and a second cycle bird was found by me, Lynette Williams, and Jasen Liu yesterday, 2/27/2022 (https://ebird.org/checklist/S103857399). 

At least two Glaucous Gulls have been seen in the main landfill pond and in the CR 104 ponds. A bright white bleached first cycle bird which I noticed in the main landfill pond on 2/18 was observed again there on 2/26 by Qiao Wei and  has been  observed almost daily in the CR 104 ponds from 2/21 to 2/27. On 2/25 I observed this bird in close proximity to an adult Glaucous Gull in the CR 104 west pond (https://ebird.org/checklist/S103721009). I believe that there are multiple first cycle birds as well because on 2/25 Michael Perrone and I watched one of them fly away from the CR 104 ponds toward the dump, but Ethan found another one in the ponds just a bit afterwards. Given the huge number of gulls present and the very low chances of re-finding singular rarities here, it certainly seems like there are multiple first cycle birds involved. 

There are many sun-bleached gulls present lately with countless birds showing pale wingtips and evenly pale backs. In addition to some pure Glaucous-winged, I think these represent a mess of hybrids containing Glaucous-winged and occasionally Glaucous. The bleaching also makes the large number of Thayer's Gulls interesting to look through, and a few apparent Kumlien's/Iceland types have been observed too.

Visiting these ponds and studying the gulls there is almost infinitely entertaining, and I would encourage anyone to go out and try. I think there is a fair chance of finding additional rare gulls here before they head back north in the next month, and I hope that additional coverage may turn up some. Happy Birding!

Best,

Konshau Duman

Davis