Slaty-backed Gull x Glaucous-winged Gull
Larus schistisagusXL. glaucescens
March 1st 2007 Choshi Chiba Japan
Slaty-backed Gull x Glaucous-winged Gull is probably not as common as Western Gull x Glaucous-winged Gull in the west coast of North America. But this type of hybrid is often hard to be noticed among crowded flocks and its state is poorly known.
This individuals looked like a pale Slaty-backed Gull at first glance. But its primaries included grayish tone, and it looked as if it were a odd Glaucous-winged Gull in some other situations.
The dark underwing bar is indistinct than in pure Slaty-backed Gull.