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 56 THE CONDOR ol. XVIII like other divers, they would tip over on their bills and disappear for a few moMaents at a time. One of the big fellows did 'sit up and take notice when a Marsh Hawk I had been watching came out and squealed at me. The transformation was amusing. From lying prone on the water head and neck down., it came up at attention, L, neck drawn high, head alert, and even its short tail tipped up. In a moment, as nothing came, back it dropped at ease, full length on the water. In bathing, Oidemia threw off its usual lethargy, ducking, flapping, spatter- ing, and splashing like a canary in a tub. On hearing a noise down the shore one day I was surprised to see one of the big black Ducks go rushing back and forth through the water and then rise and flap its wings till their white flags waved. When a week later I saw the encounter of the rivals, it strength- ened my suspicion that Oidemia had been showing off. The white flags show far across the lake and when the great birds fly evenly low over the water the velvety black of the males makes the snow white a conspicuous mark. The disappearance of these white banners when the Scorer drops to its nest is not significant because the bushes hide it then, and the disappearance of the banners when it lights on the water would hardly deceive any enemy, for Oidemia is so large and black it stands out across a lake. But on the other hand, to a female Scorer happening to be under water when her mate flew, might not the White flags be a decided help in distinguish- ing him from black-fronted Seaups scattered out over the lake ? When seeing a group of black-fronted Ducks, large and small, on the water one day I thought I had at last found a family of Scoters, but on nearer approach the small ones proved to be Seaups! If it be true that the Scoters remain paired throughout the year and the two forms deglandi and americana are together in winter the white eye- and wing-patches may well be of use in helping pairs keep together, especially in flight. In taking flight, the Scoters usually seemed to rise easily, but one that I watched flapped and splashed for some time before lifting its heavy weight. As you watch these great black Sea Ducks sitting like decoys on the still water or flying over a smooth lake, they seem decidedly out of place. But wait till a heavy wind has been blowing for a few days, waves are hammering the shore and all the other Ducks have retreated to sheltering bays. Then perhaps you will see, as I did, a pair of Oidemia head out around a point into the teeth of the wind, and as you marvel at their temerity see them settle them- selves to ride the billowing waves in their own proper marine character. The few Ducks of Stump Lake were always interesting to watch in their quiet feeding bays and along the shores both for what they were and what they might be, for one unseen before might appear at any moment. But the spectacular birds of the lake were the Gulls and Terns. The Black Terns are always striking birds, and at Sweetwater Lake' there were so many of them that it might have been called the Lake of the Black Terns. Hydrochelidon, Water Swallows, they certainly are, flocks of them skimming low over the surface of the lake, back and forth; hordes of them trooping across the passes and weaving in and out across the sky, their harsh grating kek'kek commanding attention from the shore. As I sat behind the trees and watched them, fascinated by their maneuvers, they hunted close along shore, their actions much like those of the white Tern. On long-pointed wings one would approach, the silver line from neck to elbow