Date: 5/30/26 7:17 pm From: Ethan Monk via groups.io <z.querula...> Subject: [EBB-Sightings] Some possible breeding
I spent most of my day trying to do cleanup work for the California Breeding Bird Atlas. A couple of highlights to keep any eye on:
One male Black-throated Gray Warbler was singing vigorously in Redwood Regional Park, apparently on territory, at the intersection of the Prince and East Ridge Trails. This is very late for a spring migrant of this species. Late singing birds are found every couple of years in Contra Costa, but confirmed breeding records are few and far between. I am not sure breeding has been confirmed for this species since Kevin Hintsa confirmed them feeding young at Pine Canyon in the 90s. A number of singing birds have been found over the years close by at Upper San Leandro Reservoir, and I'd guess the species is nesting regularly in this part of the county albeit in very low numbers.
One pair of Black Skimmer spent almost an hour this afternoon chasing around a third, lone Black Skimmer on Brooks Island. The only place this species has been found nesting in Contra Costa County is here (and I think only once, in 2004, although a pair was present through the summer of 2017...), and these birds should be watched. Interestingly though, the pair kept landing in the same spot... in the California Gull colony? I would have expected they would prefer the terns. Skimmers first nested in the Bay Area in 1994, and this very robust Caspian Tern breeding colony has long seemed a natural place for them to nest, but they just won't do it.
Speaking of Brooks, the Elegant numbers are way down here, but it looks like maybe 50-60 are still sitting on scrapes and attending nests. We will see if there are young soon. But the Caspian Terns seem to be doing fine, with over 300 counted today (and no downy young yet).
I have been scanning the scoters that summer on Brooks Island recently, like I do every summer looking for something unusual. Nothing last week, when I counted 72 Surf and 1 Ruddy Duck, but today I counted 73 Surf, 3 Ruddies, and 4 Red-breasted Mergansers!
Lastly, I counted 8 Pacific Wrens on ~1 mile of Pinehurst Rd. this morning, including one calling bird with a small tuft of down and a big yellow gape!
