Every night now that open water remains on city lakes, gulls gather there. They fly in by twos and threes until hundreds are loafing on the ice of Lakes Calhoun and Harriet. They must be at other lakes, too – Lake Minnetonka and at Blackdog. They feed somewhere else during the day, coming to roost in the hour of sunset. At Lake Harriet, guys gather, too, birders come to look for odd gulls. The observers roost on a viewing platform on the south side of the lake, all well wrapped against the damp cold, spotting scopes their dance partners. The men – it's almost always men – visit in low tones, shuffling their feet, bending to the scope now and then, just in case. The flock on the ice in front of them is mostly Ring-billed Gulls with a few Herring Gulls, one Franklin's Gull, and maybe a Thayer's Gull or two. What they really want to see is the Lesser Black-backed Gull that has been seen here and at Calhoun for several days. It's a bird that winters on the East Coast, an unusual, a "good" bird for Minnesota. Monday afternoon it was in plain sight at 3:30 right at this spot, in decent light, too. Not Tuesday. Not when I left, anyway. Maybe in a minute or two or 10. All observers were in place when I walked away, following the growing glow of street lights back to my car.