Black-headed Gull Chroicocephalus ridibundus

(last update: 29-05-2011)

Black-headed Gull x Slender-billed Gull

Only one record is documented of a mixed pair of Slender-billed (male) and Black-headed Gull (female) in Irkutsk, Russian Baikal region (Fefelov, 2003). This pair raised 3 hybrid fledglings.

• Chicks: colouration is generally similar but lighter than Black-Headed Gull. The distinctive grey colour on the upperparts of Slender-billed Gull chicks is absent. The second chick had less black spotting, and a large (10x12 mm) black patch on the front of the crown instead of many small spots as found on Black-headed Gull chicks (Fefelov, 2003).
• Juveniles had lighter-coloured upperparts, being greyish rather than brownish as in Black-headed Gulls. The base of the bill was pink contrasting with the dark tip, rather than the greyish-pink bill base and less contrasting dark tip of juvenile Black-headed Gull (Fefelov, 2003).

References
Fefelov I., (2004). Hybridisation between Slender-billed Gull Larus genei and Black-headed Gull L. ridibundus in Irkutsk, Russia. Forktail, 20: 96-97.