The Glaucous Gull is the second most numerous species of large gull in the Pribilofs. Present in large numbers through the winter months, but scarce during the summer this gull should be looked for in with roosting flocks of Glauous-winged Gulls throughout the year. In early spring, dozens of individuals can generally be found, but by early June, all but a few will have moved north to their breeding grounds. The identification of this species is confounded by the presence of many hybrid gulls in the Pribilofs. The translucent white primary tips, very pale mantle, heavy bill, pale iris, and barrel chest of the adult birds should make them stand out from the generally darker Glaucous-winged Gull. Immature Glaucous Gulls generally show a neatly bicolored bill, with a broad pink base abruptly meeting a black bill tip. Young Glaucous-winged Gulls tend to have a more extensively dark bill, with a black edge to the lower mandible. It is worth noting that the long photoperiod of the Arctic can bleach the primary tips of Glaucous-winged Gulls by mid summer. These washed out birds often will show very white primaries and faded mantles.