California Gull californicus

(last update: 22-12-2016 )

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John Cant
Mars Muusse

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The Peterson Reference Guides

GULLS OF THE AMERICAS

- Steve N.G. Howell / Jon Dunn -

Below is a copy of chapter 24 about California Gull, illustrated with images from this website. "we" in the text below refers to the original authors. If any errors occur in this text, please let me know and mail to marsmuusseatgmaildotcom.

CALIFORNIA GULL (Larus californicus)

LENGTH 18-23 IN. (45.5-58 CM

IDENTIFICATION SUMMARY

A medium-sized to medium-large, relatively long-winged, yellow-legged gull of W. N. America. Breeds mainly in the interior, winters mainly on the Pacific Coast. Bill medium sized (relatively slender on some females, especially first-cycle birds) and overall parallel edged with a slight gonydeal expansion. At rest, tail tip falls at or slightly beyond tip of P6, so wing projection is relatively long. Adult has pale gray to medium gray upperparts (Kodak 5-7.5; see taxonomy) with black wingtips (white mirrors on outer 2 primaries) and, in basic plumage, fairly extensive dusky head and neck streaking. Juvenile brownish overall with mostly blackish tail. PA1 variable, starting Aug.-Jan. Subsequent ages variable in appearance. All ages have dark brown eyes; first cycle has pinkish legs becoming yellowish by adult cycle; adult orbital ring red.

Medium size, pale gray to medium gray back, dark brown eyes, yellowish legs, and black bill ring with a red gonydeal spot are a distinctive combination among adults of regularly occurring New World gulls. Mostly dark brown and black-tailed first cycle told from Western Gull, Herring Gull, and Thayer’s Gull by more slender and narrow-winged build, flesh pink bill with clean-cut black tip, and from the last two also by lack of a pale inner primary panel and by dark-based greater coverts.
See Similar Species and Rarer Species sections for fuller identification criteria.

TAXONOMY

Two subspecies recognized (note: Jehl 1987): nominate californicus, breeding mainly in Great Basin from cen. Calif. east and northeast to Colo. and s. Mont.;
and albertaensis, breeding in n. Great Plains from ne. Mont. north to Northwest Territories, east to N.D.

Nonbreeding distributions of the subspecies not well known. Nominate birds average smaller (adults 19-21.7 in.; 48-55 cm) and darker gray above (Kodak 6-7.5), albertaensis averages larger (adults 20-23 in.; 51-58 cm) and paler gray above (Kodak 5-6).

STATUS AND DISTRIBUTION

Breeds w. N. America, winters w. U.S. and nw. Mex. Vagrant to Hawaii.

Breeding. Breeds (mid-Apr. - mid-July/Aug; nominate californicus) locally from s.-cen. BC. (Okanagan Lake), e. Wash., e. and cen. Ore., and e. Calif. (south to Mono Lake) e. to n. Utah, se. Wyo., and cen. Colo. Isolated colonies in w.-cen. Calif. (s. San Francisco Bay since 1980s (note: Shuford and Ryan 2000) and se. Calif. (Salton Sea since 1990s (note: Shuford and Ryan 2000)). L. c. albertaensis breeds (May-Aug.) from Great Slave Lake in the N.T., e. Alb., and Sask. south to sw. Man. and ne. S.D.

Intergradation between subspecies probably occurs in Mont. (note: Jehl 1987)

Nonbreeding. Both subspecies occur throughout main nonbreeding range, from se. Alaska to nw. Mex. (perhaps with albertaensis averaging a more southerly winter distribution), but data are insufficient to determine details of subspecies’ relative abundance or distribution. In fall, birds head west and northwest to the Pacific Coast and then drift south through the winter before heading north in spring along the coast and overland. (note: Dunn and Howell pers. obs.;
note: Pugesek et al. 1999)

Fall movements begin by early July from Wash. to Calif. and by mid-July in most other regions but not until Aug. in Prairie Provinces. Peak numbers occur mid-Aug. – early Sept. in the interior West, Sept. - Oct. on the coast. Ranges north commonly (mid-July - Nov. with peak numbers late Aug. - early Sept.) along coast north to se. Alaska and through s. third of B.C. Fall withdrawal south to wintering areas usually late Oct. - early Nov.

Winters commonly (Oct./Nov. - Mar./Apr.) from sw. B.C. south along Pacific Coast, including well offshore, to Baja Calif. Peninsula and Gulf of Calif., thence irregularly rare to fairly common south to Colima, Mex., rare or casual (Jan. - Mar.) south to s. Mex. and El Salvador (note: Komar 2001); accidental w. Ecuador. Also winters inland from s.-cen. B.C. (uncommon) locally south to e. and cen. Ore., in w.-cen. Nev., Calif. (especially Central Valley and Salton Sea), w. Neb., along Front Range, Colo., and rarely in w. Tex. Along Pacific Coast, large numbers commute daily to interior valleys where they are often the commonest gull. Generally rare or even casual in winter elsewhere in West but has been recorded as far north as se. Alaska.

In e. N. America, generally casual to rare but increasing in Midwest, Great Lakes region, Mid-Atlantic states, Southeast, and on Gulf of Mex. coast from ne. Mex. (note: King 2001) east to Fla. Has been recorded most frequently from se. Ont. (over 30 records; Oct. - early Jan., Mar. - June), including an incubating female in a Ring-billed Gull colony near Toronto in 1981 and 1982. Midwest records (south to Mo. And Ky.) scattered in July-May (mostly Sept.–late Nov. and late Mar.-mid-May); casual in interior Southeast since 2000 (mainly Jan.-Feb.). On Mid—At1antic coast, now annual Chesapeake Bay region and Outer Banks, N.C. Farthest ne. records (Oct.-Dec., Feb.-Apr.) are from se. N.Y. and Mass.

Northbound movements in Calif. start Feb. on cen. coast, mid-Feb.-Mar. in interior. Arrival at breeding grounds in e. Calif. and e. Ore. by mid-Mar., continuing into Apr. On coast and in s. interior of B.C., movement evident by mid-Mar., peaking early Apr. From w. Great Plains (for example, w. Neb.) north through s. Alta. arrivals evident mid-late Mar., but not until mid-Apr. in sw. Man. Spring movement continues throughout W. N. America into May. Nonbreeding visitor (late May-July) along Pacific Coast from s. B.C. south to nw. Mex. (more commonly from cen. Calif. north), and at Salton Sea; also uncommon in se. Alaska, rare in interior West Well away from breeding areas, and casual north to s. coastal Alaska and sw. Hudson Bay, exceptionally to Arctic coast of Alaska.

END OF PART 1.

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