The amount of white in the wingtip varies within species, confusing the issue, but generalities are possible. It usually has long, white mirrors contacting the white tip spots on one or more primaries. Larger gulls have relatively thicker bills, an important aid in judging size, especially where comparisons are not possible. Stays the same all year in adults, although brightens in breeding season in some species. Gulls that otherwise look fully adult can still have these intermediate bills.
Intensity varies in each species from dull to bright pink or yellow.
Note only the larger gulls vary from the usual brown bird-eye color, perhaps for species recognition. Usually less intense and less obvious in winter. The extent and intensity of head streaking in winter is somewhat variable. All rights reserved.