Below is a belated summary of a Sunday 4/21/2024 Big Day that Richard Jeffers and I (Mike Rogers) did.

We started out at 3:05am at the Mountain View Forebay, hoping to get our list started with birds that are vocal at night. We did hear 2 VIRGINIA RAILS and a SEMIPALMATED PLOVER, but not much else of note. Likewise, a stop at the Palo Alto estuary added a BARN OWL and the day's only LONG-BILLED CURLEW, but not the hoped for Short-billed Dowitcher or Ridgway's Rail. A check of Alviso turned up the day's only NORTHERN PINTAIL and a pair of CINNAMON TEAL, as well as a few expected shorebirds.

Heading over Quimby Road to Grant Ranch, we added WESTERN SCREECH-OWL and several GREAT HORNED OWLS as well as a few early vocalizing songbirds. A stop at the pullout at mile 13.9 above Grant Lake just before 6am added more species, including a heard-only COMMON POORWILL. A stop at milepost 15.5 added one of only two HERMIT THRUSHES on the day, as well as more morning bird song.

Day birding began in earnest at Smith Creek at 6:14am. A very vocal RED-BREASTED NUTHATCH upslope of the fire station was a surprise and our only one of the day. Otherwise, migration was modest and we worked for over 2.5 hours to find many of the expected less common migrants, including 2 HAMMOND'S FLYCATCHERS (both found by their calls), 1 WESTERN FLYCATCHER, 4 WARBLING and 1 CASSIN'S VIREOs, 8 ORANGE-CROWNED WARBLERS, 2 singing NASHVILLE WARBLERS, 14 YELLOW-RUMPED WARBLERS, 1 singing BLACK-THROATED GRAY WARBLER, 4 TOWNSEND'S WARBLERS, 2+ singing HERMIT WARBLERS, 3 WILSON'S WARBLERS, 3 WESTERN TANAGERS, and 4 LAZULI BUNTINGS. Other notable birds included a singing CHIPPING SPARROW, a female PHAINOPEPLA, and a male HOODED ORIOLE.

Grant Lake had limited diversity and no eagles, but PIED-BILLED GREBES and AMERICAN COOTS already had precocial young. We found no wigeon, a species we missed the whole day for the first time in over two decades of spring big days! The ranch house area was also pretty quiet, but added 2 more WESTERN FLYCATCHERS, our first WESTERN KINGBIRDS, and a SELASPHORUS HUMMINGBIRD, but no Vermilion Flycatcher like last year. A goldfinch flock near the wishing well sounded like it held a Lawrence's Goldfinch, but we could only find 6 AMERICAN GOLDFINCHES and 5 PINE SISKINS among the LESSER GOLDFINCHES.

Lake Cunningham added 4 GREEN HERONS, 3 GREATER YELLOWLEGS, at least 10 GREAT-TAILED GRACKLES, and an EARED GREBE, but we found all these species again later in the day. A quick stop at the Rosicrucian Museum on the way to the bay turned up a male BLACK-CHINNED HUMMINGBIRD perched on the telephone wires and a flock of 40 CEDAR WAXWINGS (we had seen a single waxwing earlier at Smith Creek).

Arriving at the bay, the Gold Street ponds provided the only SPOTTED SANDPIPER for our day. Alviso Slough behind the cannery had 6 LESSER SCAUP. Precocial young BLACK-NECKED STILTS were already in evidence along the EEC entrance road. Scoping ponds A16 and A18 from the EEC didn't turn up much besides impenetrable heat haze. We ended up with only Ring-billed and California Gulls on the day (combined with no lingering wintering geese, this significantly impacted our species total).

The Sunnyvale Water Pollution Control Plant/Pond A4 turned up 2 WESTERN KINGBIRDS (no Tropical) and 2 COMMON GALLINULES but again a low diversity of wintering waterfowl. A flock of 20 all-white pigeons looked out of place flying over Pond A4. Things got better when we circled the Mountain View Forebay and we added a pair of SURF SCOTERS and 13 BLACK SKIMMERS on Shoreline Lake, 5 CANVASBACKS, 2 GREATER SCAUP, and a BUFFLEHEAD on Pond A1, and a MARBLED GODWIT and 2 DUNLIN on Charleston Slough.

A stop at the Emily Renzel wetlands on the way to the Palo Alto Baylands added the continuing HARRIS'S SPARROW. Shorebirds were already pretty far out at the boat launch at the estuary mouth, but we added our first BLACK-BELLIED PLOVERS (4) and a WHIMBREL for the day. And at 4:30pm, we were both scoping the bay edge when a RED-THROATED LOON flew by heading north just outside the yacht harbor mouth. A completely unexpected bird and the latest I've ever seen on an SCL county spring big day (the other April record being from 19 Apr 2008)!

After this, we headed to the south county, stopping along Hellyer Avenue to add SAY'S PHOEBE. Ogier Ponds did produce the SOLITARY SANDPIPER, but not the hoped for kingfisher, Wood Duck, or Osprey. A flock of 13 BUFFLEHEADS was a surprise though! Palm Avenue added 2 YELLOW-BILLED MAGPIES and a KESTREL; both species were also along West Laguna Ave as well. At 7:11pm, we arrived at the Calero boat launch and soon added 5 PURPLE MARTINS (2 males), our first CLARK'S GREBES, but no Osprey or eagles.

We finished our day at the Stile Ranch trailhead, finally catching up with RUFOUS-CROWNED SPARROWS and hearing two singing HORNED LARKS as a bonus! Heading back home we were treated to another BARN OWL at 8:14pm.

All-in-all we had lots of misses, but ended up with 148 species, 4 of which I have not found on previous Santa Clara County April Big Days (Solitary Sandpiper, Purple Martin, Phainopepla, and Harris's Sparrow). As noted above, American Wigeon was missed for the first time ever. Hutton's Vireo I've only missed once before, but was presumably missed this year largely because we spent the morning in the Diablo Range instead of along Skyline and at Stevens Creek County Park, as in most past years. Conversely, I've missed Ruby-crowned Kinglet the last 11 years, but the odds should have been better at Smith Creek, where I can normally find one at this time of year. And definitely we need to find a better/more accessible place for lingering gulls!