North American Birds

VOLUME 70 NO1 2017

A Quarterly Journal of Ornithological Record Published by the American Birding Association. The mission of the journal is to provide a complete overview of the changing panorama of our continent’s birdlife.

Issue link: http://nab.aba.org/i/936087

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V O L U M E 7 0 ( 2 0 1 7 ) • N U M B E R 1 113 N O R T H E R N C A L I F O R N I A BITTERNS THROUGH CRANES A Least Bittern attended 2 young at Las Gal- linas, Marin 3 Aug (ph. STu, Jen Sanford), where one or 2 birds were seen through 17 Sep (ph. mob.). An ad. accompanied by a juv. was photographed at Bridgeway Island Pond, Yolo 9 Aug (ph. KSw), following the sighting of a single bird there 7 Aug (GEw). Another was seen at Thermalito Afterbay, Butte 1 Aug (MtF). Very rare in Alpine, a Green Heron was found in Markleeville 10 Sep (EP). An ad. Glossy Ibis in basic plumage at the Yolo Bypass W.A. 18 Sep was Yolo's fifth (p.a.; ph. JCS, TEa, JSL). Marin's Black Vulture was seen again near the Fish Docks at P.R.N.S. on three days dur - ing 21-28 Aug (ph. DSg et al.). Coastally mi- grating Northern Goshawks consisted of juvs. heading s. past Jenner Headland Preserve, Sonoma 5 Nov (Larry Broderick) and banded at Hawk Hill in the Marin headlands 25 Nov (the sixth banded in 30 years of banding ac - tivity; fide Rich Cimino). As usual, south- bound Broad-winged Hawks were reported in numbers at Sonoma, Marin, and S.F. hawk - watches 18 Sep–10 Oct (ph. m.ob.); a total of 8 birds (all juvs.) in San Mateo, Santa Clara, Santa Cruz, and Monterey 19 Sep–29 Oct (ph. m.ob.) was only half last year's record showing in these same counties, but still above aver - age and much greater than historical levels. Swainson's Hawks were likewise reported in good numbers in central coast locales from So - noma to Monterey, with 5 juvs. detected over outer Point Reyes, Marin 19 Sep–9 Oct (ph. m.ob.) alone. Also notable were 3 birds in Humboldt 1 Sep–13 Nov (TWL, RHw, CDu). A juv. attended by an ad. along Lone Tree Rd., San Benito 4 Aug (DLSh) confirmed breeding at that location for the third year in a row. Lin - gering birds away from known wintering areas included one in n. Dublin, Alameda 19 Nov (MST), an ad. in Coyote Valley, Santa Clara 17 Nov (ph. PDu, Joyce Wong), and a juv. there 27 Nov (ph. Douglas Joo et al. fide Lisa My - ers). Harlan's Red-tailed Hawks were reported from five locations 5 Nov+ and included an ad. returning for its 13th year near Bayside, Humboldt 5 Nov+ (SWH, ph. EE et al.). Mendocino's second Yellow Rail was seen at MacKerricher S.P. 8 Nov (†TEa, FS). A pair of Black Rails with 3-4 chicks at the Alviso Marina 26-27 Aug (v.t. Stephen Peterson, Maya Gokla - ny, WGB) provided the first confirmed breed- ing in Santa Clara in over 100 years. Following last season's two Jul reports, a Sandhill Crane was seen again in Del Norte, at Lake Earl W.A. 4 Aug (GrH). Also notable for date and location was a Sandhill Crane flying n. in San Mateo 6 Sep over Pilarcitos Creek mouth (Tom Johnson et al.), El Granada (†Keith Gress), and Pacifica (Murray Cherkas). Mendocino recorded its first Black Storm-Pe - trels, with 8 off Fort Bragg 27 Sep (TEa, RJK, †KHv, m.ob.). Least Storm-Petrels tend to be more frequently reported in the Region in warm-water years. This season, only a handful were reported, and no convincing documenta - tion reached the Regional Editors; birders are encouraged to document this species' occur - rences well to help determine its true status and abundance. An ad. Blue-footed Booby continued at F.I. to 28 Oct (ph. Point Blue) and what may have been a different bird was there 13 Nov (Robert Snowden). We seem to break our Brown Booby record each fall as this species' normal range expands to include northern California. At F.I., Brown Boobies were seen daily throughout the period, with average daily counts of 6 in Aug, 14 in Sep, 19 in Oct, and 12 in Nov; the high count was 30 on 23-25 Oct (Point Blue). Eigh - teen were seen elsewhere, in all coastal counties north to Humboldt, where one was on the n. jetty of Humboldt Bay 16 Oct (Samantha Ba - con, Brad Elvert, †TMcK, ph. CDu). One riding a ship near Alcatraz, S.F. 30 Oct (fide LKh) was rare inside S.F. Bay. The long-staying Northern Gannet continued to be highly mobile and conspicuous, being recorded on F.I. most days (Point Blue) but also being seen at Chimney Rock, Marin and Moss Beach and Pillar Point, San Mateo on multiple days (m.ob.). resentative high counts were 24,100 at Wilder Ranch S.P., Santa Cruz 22 Oct (AMR), 12,800 in one hour at Point Pinos, Monterey 30 Sep (BLS), 11,600 at Moss Beach, San Mateo 5 Oct (RSTh), and up to 10,000 off Fort Bragg, Mendocino 7 Nov (CEV et al.). Larger numbers pushed farther n. than have ever been previ - ously recorded, with a Humboldt high of 3,500 off Humboldt Bay 7 Oct (Brad Elvert, Samantha Bacon, EE) and a Del Norte count of 60 off the Wilson Creek mouth the same day (RbF, TKz); neither county had ever had counts exceeding single digits! Black-vented Shearwaters were also more abundant than usual further offshore; 4,000 were at F.I. 12 Oct (Point Blue), where the seasonal total of 17,672 nearly equaled the cumulative sum from the previous 45 years, and 25 were 46 km off Fort Bragg, Mendocino 1 Oct (JM). The excitement of such events is tempered by the realization that severe short - ages of food within the species' normal range must have been responsible for forcing so many individuals so far afield. Six Ashy Storm-Petrels at the Eel River Can - yon off Humboldt Bay, Humboldt 29 Aug (RbF, SMcA, Mark Colwell, m.ob.) provided a good count so far n. A Wedge-rumped Storm-Petrel at Cordell Bank 22-23 Aug (ph. SNGH et al.) provided Marin's first record and the northern - most of the Region's six records. Continuing the theme of northerly occurring storm-petrels, SA Although seawatching from coastal promontories is a popular pastime, there have been no standardized, high-intensity seawatching efforts in the Region (away from F.I.). To address this lack of data, Tony Leukering, with help from several Monterey-area bird - ers (primarily PFw, JGa, BTM, DR, BLS, CSc, and Robert Shields) and sponsorship by the Mon- terey Audubon Society, began a six-week survey this fall from one of the Region's premier seawatching locations, Point Pinos, Monterey. Surveys were conducted dawn-to-dusk each day 1 Nov–15 Dec, with data being entered into eBird in hourly bins. The survey was timed to catch peak southbound migration of Pacific Loons, tallying 148,956 through 30 Nov, but all migrant seabirds flying s. past Point Pinos, as well as all rarities, were also tallied. Though the survey provides only a brief snapshot of seabird migration, the intensity of the effort and stan - dardization of the methods (e.g., with one primary observer) produced robust data on seabird occurrence here, as well as a useful comparison for future efforts at Point Pinos and elsewhere. Interesting Nov totals from this effort include counts of only 995 Red-throated and 169 Common Loons (indicating the later migration of these species compared to Pacific Loon), 15 Red-necked Grebes (higher than expected), 46 fly-by Ring-billed Gulls (this species is rare along our rocky shorelines, but obviously more migrate along the coast, without stopping, than was previously known), and 127 Short-tailed Shearwaters (vs. 42 Sooties and 84 Short- tailed/Sooty Shearwaters, suggesting the relative inshore abundance of these two species in Nov in years when Sooties depart early, as they did in 2015). An incredible total of 57,062 Black-vented Shearwaters likely included some repeat birds due to this species' movements along the coastline, but this was the second most abundant species recorded and this tally represents perhaps 20-25 percent of the global population (Birdlife International, http:// www.birdlife.org/datazone/species/factsheet/22698246). The tally of 6 Royal Terns, with 4 on 6 Nov (likely related to warm-water conditions) was also an interesting report. Other notable records from this survey appear in the main text.

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