Jim Gain is one of the Valley’s most accomplished birders. He’s an even better bird photographer. Last year, Gain found Black Skimmers in Stanislaus County, the first-ever documented record of this species for the county. April 27, Jim found another, even less likely bird, the first documented sighting for the entire Central Valley. Here’s Jim’s account of seeing and photographing one of the rarest birds to ever visit the Valley. ed
The Modesto Water Treatment Plant is the single biggest magnet for unusual bird species in Stanislaus County. Last April 27 was one of the last public access days so far this year. Since then, ongoing construction projects have resulted in no access until further notice.
Late April is the midst of shorebird migration and I needed several more species photographs for my Stanislaus County Big Year Photography Challenge. On April 27, the weather was optimal for photography, cool with a gentle southeast breeze, thin cloud cover, and intermittent light rain showers.
Jim Ross and I were hoping to add some missing shorebirds to our year list but we had also missed on Western Gull at the Recology dump in the northwestern portion of the county, so we were hoping to find this uncommon to rare species at the treatment plant.
Our clockwise circuit around the lower ponds was pleasantly delayed by a flock of Yellow-headed Blackbirds — uncommon in Stanislaus County. Swallows and pipits were everywhere, as were many Eared Grebes sporting stunning “ear” plumes.
As our slow cruise turned south between ponds 2 and 3, I saw a large, dark- mantled gull resting on a tree stump in the middle of a pond full of Northern Shovelers. I immediately thought it could be our Western Gull target bird.
It was at this point that I made a critical mistake. I quickly calculated that the gull was a good way from the road and wasn’t likely to flush at our approach. So I decided NOT to get a scope on it and instead to get closer. I might have been right about the gull not flying off had it not been for the 900 Northern Shovelers that did!
As the ducks fIew off, I lost the gull amongst the cloud of waterfowl. My brief look seemed to fit the size, shape and color of a Western Gull, but at that distance, a positive ID was impossible. As we began to drive on, Jim Ross’ optimistic view was that the bird would land at the far end of the pond. And, as we turned east at the end of the levee, there it was.
I’m familiar with our local gull species and as I began to go through my mental checklist of features to focus on, things just weren’t adding up. The body shape and color, as well as the large bill, seemed to point to a Western Gull, but a Western Gull should have pink legs and these legs weren’t pink, they were peachy yellow.
I then went down checklist of features that might point to rarer species. What dark-mantled gull had yellow legs? Based on my experience with other gull species, I knew I had to get flight shots for a definitive identification. When the bird finally took off, it made two lazy circles overhead, seemingly unbothered by the whole encounter.
Eventually. the bird flew off to the south, where we lost it in the clouds and were left with quite the conundrum: WHAT SPECIES WAS IT? At the time, trying to confirm details by looking at the LCD panel on the back of my camera wasn’t getting us anywhere. I felt like I was trying to force a round peg into a square hole. The pieces just didn’t fit. We left the ID to be determined after I could take a careful look at my photos.
Once home and with time to study my photos closely, I was able to determine this large gull had crisp, clean, body and head feathers, but the flight and tail feathers were ragged and worn. The head was bright white with no streaking or smudging. The bill was large, thick and yellow, with a large red spot on the lower half. The eye was very pale yellow with a yellow ring around it. The back and upper wings were dark, slaty gray. The legs were yellow.
These features suggested the bird was a near-adult in breeding plumage. A black band across the taiI also suggested a breeding-plumaged adult. Western Gulls in breeding plumage would never have yellow legs. The only gull that fit these features was the Yellow-footed Gull. Problem was, there had never been a confirmed sighting of this species in the entire Central Valley.
About the Yellow-footed Gull
Arguably the Gulf of California’s only endemic seabird species, the Yellow-footed Gull (Larus livens) resembles the Western Gull (L. occidentalis) with its bulboous bill and dark gray mantle. Its total population is smaller than than of any other North American gull.
Typically breeding in the Gulf of California, Yellow-footed Gulls migrate to California’s Salton Sea after the breeding season. They arrive there primarily in late June, with peak numbers in August.
Our April 27 sighting was the first documented occurrence of this species in the Central Valley. Prior to 2022, there were no recorded observations of Yellow-footed Gull in California north of Los Angeles County. Since 2022, there have only been three other records, with one in the desert (Inyo County) and two in the Monterey Bay region.
Due to increased salinity, the Salton Sea cannot sustain the prey items Yellow-footed Gulls need to survive. Climate change is increasing ocean temperatures in the Gulf of California and evapotranspiration rates in the Salton Sea. The direct result is the depletion of primary food sources for the Yellow-footed Gull and will likely result in the dispersal of starving gulls in many directions, including northward to the San Joaquin Valley, and locations like Stanislaus County.
Valley birders take notice! There might be more on the way.
