These pictures were taken by me in Mid-March at Maagen Mikhael fish ponds, north of Tel Aviv, Israel (except where stated otherwise).
I presume them all to be the most abundant locally wintering form of yellow-legged Herring-type gull, namely Armenian Gull Larus armenicus, but cachinnans, michahellis, and heuglini occur (listed in diminishing abundance). Some of the stated ageing is tentative - I would like to receive informed comment:-

01: four adults (standing; swimming), with head-shapes varying from "soft" and rather rounded to flatter and more-sloping
02: adults and 4CY (flying)
03: 2CY (on water) - two photos of the same individual
04: 3CY (standing, flying)
05: various ages (standing, swimming)
06: a 2nd-basic (standing) from Georgia in February
07: two definitive-basics (standing) from Georgia in February
08: two definitive-basics (standing) from Cyprus in January