Due to the dark flecking on the primary coverts I think this is a third winter bird molting into its adult basic plumage. The adult primary feathers have yet to fully attained therefore it is difficult to rely on the upperwing pattern. Leg color appears to match Heuglin's Gull well. The mantle color looks a bit pale for Heuglin's Gull but I guess this is perhaps due to bright sun. On balance I would say this a Heuglin's Gull or at least hybrid with at least some Heuglin's Gull progeny.
