Though most of our breeding California Gulls have left the Mono Basin for fishier coastal waters, we do have one most unusual gull keeping us company: a young Western x Glaucous-winged Gull hybrid. The parent species both breed on the Pacific coast and rarely venture inland.
In fact, no Western Gull has ever been seen in the Mono Basin and only a single Glaucous-winged Gull has (and that was 20 years ago). There is an extensive hybrid, or intergrade zone, in the Puget Sound region of Washington State where hybrids and backcrosses are very common. Some studies have even shown that hybrids have higher breeding success than either parent species, a rare phenomenon in the avian world. Our bird, which has been at Grant Lake Reservoir for nearly two weeks, can be identified as a Western x Glaucous-winged cross by the color of the primaries (which are only a slight hint darker than the mantle feathers) combined with the massive black bill and long pink legs. If you’re in the area it’s a worthwhile bird to go and check out! It has been seen most frequently near the south end of the reservoir.