Chroicocephalus

Trivial name	Latin name
Black-headed Gull	Chroicocephalus ridibundus
Slender-billed gull	Chroicocephalus genei
Grey-headed gull	Chroicocephalus cirrocephalus
Silver Gull	Chroicocephalus novaehollandiae

comparison of wing and tail configuration¹

¹ According to Hartmann (2000a, 2000b and 2016)