Black-headed Gull ranges across Eurasia but is replaced in North America by the similar Bonaparte's Gull. A rarity in California, this is the first record for Santa Cruz County. First noted 27 December 2023 at the mouth of Aptos Creek by David Sidle. Today we found it north of the creek at Seacliff State Beach. It is an adult in winter plumage lacking the dark hood. Formerly included in the genus "Larus," it bears a strong resemblance to Brown-hooded Gull (Chroicocephalus maculipennis) of the South American southern coasts. The two were considered conspecific by Hellmayr. Brown-hooded has a slightly darker mantle, narrower dark subterminal band on its primaries, more dark at the bases of its outermost primaries, and distinct white primary tips.
