My recent gull class field trip found ten species of gulls (Western, Glaucous-winged, Glaucous, Herring, Thayer’s, California, Ring-billed, Mew, Bonaparte’s, and Heermann’s). This was a new record for the class, and it got me wondering. How many species of gulls could one conceivably find in one day in Oregon?
The best time for such a quest would be early November. By then, the wintering species would be here, and there are usually a few lingering Heermann’s Gulls that haven’t gone south yet. Bonaparte’s Gulls are migrating south at this time, as well. If you waited until December, the migrants would have already moved on. By late January, many of the wintering birds have already left.
The best location for a gull quest would be the coast. Eight species regularly occur in the Willamette Valley as well, (Western (rare), Glaucous-winged, Herring, Thayer’s, California, Ring-billed, Mew, and Bonaparte’s), but anything else would be extremely rare. Ring-billed can be challenging to find on the coast, but you can usually find one among the Mew Gulls in the estuaries. So with some searching, you could count on these eight species, plus Heermann’s makes nine.
If your quest occurred the day after an autumn storm, you would have a chance at two pelagic species, Black-legged Kittiwake and Sabine’s Gull. That would bring your total to eleven.
To exceed eleven species, you would need to find a rarity. Glaucous Gull is probably the most likely. Other less likely candidates include Lesser Black-backed, Slaty-backed, or a wayward Franklin’s.
So if you could find a rarity (or go see a previously reported bird) and timed your quest to coincide with some west winds, you could conceivably see twelve gull species in a day. Has anyone done this? This sounds like a noble quest to me.