Ring-billed Gulls in the foreground and Herring Gulls behind, along the shore at Hobie Point, Lake Hefner
WD: There are three Herring Gulls in back and two Ring-billed Gulls in front. The Herring Gulls are larger with pink legs and a red bill spot with a little dark smudge next to it. The Ring-billed Gulls are smaller with yellow legs and a complete black ring on the bill--the top of a yellow leg
is just visible on the gull in front, the bills can't be seen. The two Herring Gulls in front are males. Note the longer, thicker bill with more pronounced gonydeal angle (the bump on the bottom), thicker neck (also longer when it can be compared), larger head with more sloping forehead (i.e. more wedge-shaped) and more heavy streaking on the neck. This photo does a fair job of showing the male/female differences. The differences are more apparent when there are more gulls to look at. Sometimes females will all be roosting in a group, very regimented, with larger males scattered around the outside which makes the differences very clear to see. Male Herring Gulls
fight with one another over prime nest sites. The fights are not trivial. In one case where two males were tracked and observed after a fight, neither bred that season, even though one of them had established a mate and a nest. Notice that all three Herring Gulls have light eyes, more specifically the iris is a light yellow. The HG on the right is showing the underside of P10, the outermost primary on the far side. There is a large, white spot visible known as a mirror. The mirror is not too large as mirrors go. The default type of Herring Gull in Oklahoma is the so called western type of which the gull with the mirror showing is an example. Western Herring has extensive black on the outer primaries and a single white mirror on P10. The other main type of Herring Gull is the northeastern type. It has a larger mirror on P10 plus a small one on P9 and less extensive black on the outer primaries. A small percentage of northeastern Herring Gulls are as lightly marked on the primaries as Thayer's Gulls. Herring Gulls and Ring-billed Gulls have the same gray color on the back. This is not generally true of different species of gulls. I doubt if it is a coincidence. The Ring-billed Gulls may be trying to mimic the appearance of their bigger, stronger relatives.