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4 Thrasher Day and plenty of warblers + huge flock of Bonaparte’s Gulls on Lake Cuyamaca

4 Thrasher Day and plenty of warblers + huge flock of Bonaparte’s Gulls on Lake Cuyamaca
By – 11:52 am
Yesterday, Friday April 15th, Josh Beck and I spent the day birding the Cuyamacas and Anza Borrego State Park. Our target for the day was the continuing Bendire’s Thrasher at Clark’s Dry Lake, but we got distracted early on in the mountains with good numbers of migrants.

Starting up Route 79 early in the morning, we stopped at Paso Picacho Campground as well as a pullout about a mile or two further north in Cuyamaca Rancho State Park and found some nice birds including 3 fresh male HERMIT WARBLERs, a flyover PURPLE MARTIN, and a few heard-only MOUNTAIN QUAIL. TOWNSEND’S, BLACK-THROATED GRAY, NASHVILLE, WILSON’S, and ORANGE-CROWNED were all present in good numbers, making for an especially birdy morning at nearly every stop.

Heading to Anza Borrego proper, we stopped at Yaqui Wells but couldn’t find a Ladder-backed Woodpecker (will keep trying). Birding across the street was very fruitful in terms of migrants, and at the Tamarisk Grove Campground we found a migrating BELTED KINGFISHER which headed off quickly into the desert (an odd sight).

Continuing to Clark’s Dry Lake, we eventually found the BENDIRE’S THRASHER continuing in its preferred location in the first large clump of Mesquite (pins on eBird). Here we also found some BREWER’S SPARROWS, as well as a PACIFIC-SLOPE FLYCATCHER and loads of warblers (namely WILSON’S, ORANGE-CROWNED, and NASHVILLE).

Testing our luck for the day, we headed across the small section of dry lake further in and got lucky finding a pair of somewhat confiding LECONTE’s THRASHERs. We were quite pleased with our luck, so we pushed on to the Mesquite Bosque afterwards and soon after located both a singing male LUCY’S WARBLER, and a pair of fighty CRISSAL THRASHERs (making this our third thrasher species of the day).

We broke for lunch, eating in Borrego Springs, before heading back to San Diego proper for an “early” return from the field. After a quick stop in Julian, we passed Lake Cuyamaca where I noticed a large raft of white birds on the lake. Pulling over, we quickly realized it was a flock of almost entirely alternate plumaged BONAPARTE’S GULLS – about 175-200 birds! Quite a sight, I’ll count the birds in my photos for a true total – it sounded as though there was a movement of Bonaparte’s Gulls in the county yesterday as seen in Nick Barber’s eBird list here: https://ebird.org/checklist/S107114038

The lake also had a flock of ~20 peeps (likely Western Sandpipers) trying to land within the flock of Bonaparte’s Gulls, as well as a flock of WILSON’S SNIPE. Checking the waterfowl, we located a pair of CANVASBACK, a RING-NECKED DUCK, some RUDDY DUCKs, and an AMERICAN WHITE PELICAN.

Wrapping up the day, I pushed us to find a fourth species of thrasher for the day – and we eventually located a CALIFORNIA THRASHER off of Route 79 along Wildwood Glen Lane (just north of the junction of 79 and I-8).

We totaled nearly 80 species for the day, with a bulk of it spent in the desert, but with a few very high-quality species rounding out the list.

I did wonder if anyone’s done a 4 thrasher day before in the world, especially in one county. If anyone has, I’d love to hear how you did it and what the 4 thrashers were!

Good Birding,

Nathan Goldberg
San Diego, CA