Thursday, September 26, 2013

Eureka! Birds of San Luis Obispo County - August 2013

Identification of similar looking species can be tricky. Locally, Lesser and Greater Scaup, Sooty and Short-tailed Shearwaters, Lesser and Greater Yellowlegs, the Empidonax flycatchers, and Hutton’s Vireo vs. Ruby-crowned Kinglet are a few local identification challenges. One challenging pair that is underappreciated, or just not known to some observers, is Rufous vs. Allen’s Hummingbirds. Allen’s, which breed in SLO County, arrive in January (sometimes late December) and are present on breeding grounds (think coastal riparian areas like Oso Flaco Lake) to mid-July. In spring, the bulk of Rufous pass through the county from mid-February to the end of April, and the bulk of fall migrants are present mid-July through August. Male Allen’s have mostly green backs while male Rufous show mostly or all rufous backs, though some are mostly green. In fall, females and juveniles of both species are very similar in appearance and are best separated by tail feather shape and markings. These features are not easily observed in the fi eld and photos of spread tails are generally the best way to separate these species. An adult male with no green in the back can safely be identified as a rufous, but birds with both green and rufous in their back are best separated by the shape of the R2 tail feather shape. Sheri Williamson, author of Hummingbirds of North America, recently posted a great Rufous/Allen’s discussion on her blog that includes photos and drawings that emphasize these points. Check it out at http://fieldguidetohummingbirds.wordpress.com/2010/09/06/rufous-vs-allens. It’ll make you reach for your camera next time one of these species shows up at your feeder.

According to eBird, 179 species were recorded in SLO County in August and a total of 307 species have been recorded in 2013. Abbreviations: MDOSP = Montana de Oro State Park; OFL = Oso Flaco Lake; PSBOC = Pismo State Beach Oceano Campground; WRR = Whale Rock Reservoir.

WATERFOWL: The SNOW GEESE at Oceano County Park and Laguna Lake continued through the period (mob) and will likely be present through winter. A few BRANT continued along the coast with six at the mouth of Arroyo Laguna on 12 Aug (TME) and nine at Morro Bay on 17 Aug (TME). As is typical in Aug a few WOOD DUCKS were at Whale Rock Reservoir where the high count was 12 on 2 Aug (MLS), but the highest number recorded was at the Atascadero Wastewater Ponds where 68 were present on 18 Aug (TME). A lone GREEN-WINGED TEAL seen at Morro Bay on 17 Aug (TME) probably summered on the bay. Both the male RING-NECKED DUCK and GREATER SCAUP continued through the month at Whale Rock Reservoir (TME,MLS,KLP) where a female RING-NECKED DUCK joined them 29-31 Aug (TME). The eclipse-plumaged male HARLEQUIN DUCK remained at Estero Bluffs State Park through at least 23 Aug (MLS).

CONDOR THRU RAIL: CALIFORNIA CONDOR is rarely seen in the county and always generates a lot of interest, so it wasn’t surprising when one photographed near Pismo Beach on 19 Aug (MT) led to several requests for the photo. It was determined that this was bird #470, which was most recently sighted along the Big Sur coastline nine days earlier. Rare in the dry interior, a RED-SHOULDERED HAWK was at a ranch in the southern Carrizo Plain National Monument on 21 Aug (KS). The source of a juvenile BALD EAGLE at Whale Rock Reservoir on 8 Aug (KLP) was unknown; it was not reported again at this regularly birded location. Early rail arrival dates at OFL were 3 Aug for VIRGINIA RAIL (CDL) and 13 Aug for SORA (MLS).

SHOREBIRDS THRU SWIFT: A count of 300 SEMIPALMATED PLOVERS along the Morro Bay Sandspit on 11 Aug (JSR) provided a new high count for the county. Two SOLITARY SANDPIPERS were found, one at a small ag pond along Hwy 33in the southeastern corner of the county on 13 Aug (PAG) and the other, a juveni├╗─▒, at the Atascadero Wastewater Ponds on 18 Aug (TME). The lone LESSER YELLOWLEGS report involved two juveniles at OFL on 30 Aug (DML). A SEMIPALMATED SANDPIPER at Morro Bay on 22 Aug (JSR) was only the second this fall. The lone BAIRD’S SANDPIPER report this fall was of two juveniles at Cayucos 14-22 Aug (TME). Nine MARBLED MURRELETS at three locations along the north coast on 20 Aug (MLS,KLP) had been scarce up to that date. A WHITE-WINGED DOVE in Cayucos 27 Aug-2 Sep (KLP,MLS) was within the expected fall period of mid-Aug to early Oct. Ten VAUX’S SWIFTS at the Atascadero Wastewater Ponds on 20 Aug (WK) were either the fi rst fall migrants or lingering family groups that bred in the area.

FLYCATCHER THRU BLACKBIRD: A pulse of migrant WILLOW FLYCATCHERS was evident on 31 Aug when individuals were at Islay Creek mouth, MDOSP (TME,MLS), the Pismo North Beach Campground (TM), and the Pismo State Beach Oceano Campground (MLS). A slightly early fi rst-of-season RUBY-CROWNED KINGLET was at the Islay Creek Campground, MDOSP, on 31 Aug (TME). The fi rst fall “eastern warbler” was an AMERICAN REDSTART at PSBOC on 21 Aug (MLS). Early dates for two “western” warblers were 20 Aug for a NASHVILLE WARBLER at Atascadero (WK) and 17 Aug for two TOWNSEND’S WARBLERS at PSBOC (JMC). A GRASSHOPPER SPARROW at the Fiscalini Ranch Preserve on 25 Aug was either a lingering breeder or a fall migrant (JSR). A WESTERN TANAGER along Estero Ave in Morro Bay on 1 Aug (KLP) arrived at the beginning of the expected fall migration period. Another fall migrant, and one that is rare in fall, was a female INDIGO BUNTING found at PSBOC on 31 Aug (TM). Two YELLOW-HEADED BLACKBIRDS were in a mixed fl ock of blackbirds along Dana Foothill Road in Nipomo on 21 Aug (MM).

OBSERVERS: Thanks to everyone that reports their sightings, primarily via the yahoo “slocobirding” listserv and eBird, including those cited above: Jamie M. Chavez, Tom M. Edell, Peter A. Gaede, Will Knowlton, Dave M. Lawrence, Cheryl D. Lish, Michelle Maani, Tristan McKee, Kaaren L. Perry, Jim S. Royer, Brad K. Schram, Kathy Sharum, Maggie L. Smith, Monte Taylor, and many observers (mob). For seasonal status information about birds mentioned in this report, consult the Morro Coast Audubon publication “The Birds of San Luis Obispo County, California” or contact Tom Edell at (805) 995-1691 or tedell@aol.com....Tom Edell