bird 7 - upperwings.
Perhaps this is a hybrid with Vega Gull. A few adults of that taxon
show such large white mirrors on P9-10, as well as extensive white
on tongue-tips of P6-8. Still, the white mirrors are quite large
even for adult Slaty-backed Gull, so perhaps some consideration should
also go to a hybrid with Glaucous Gull?