These birds, in conjunction with several others, sometimes collect together in such flocks, as to seem, at a distance, a large cloud of thick smoke, varying in form and appearance every instant, while it performs its evolutions in air. As this cloud descends and courses along the shores of the ocean, with great rapidity, in a kind of waving, serpentine flight, alternately throwing its dark and white plumage to the eye, it forms a very grand and interesting appearance. At such times the gunners make prodigious slaughter among them; while, as the showers of their companions fall, the whole body often alight, or descend to the surface with them, till the sportsman is completely satiated with destruction.
Suckley (1860) found them equally abundant in the Puget Sound region, for he writes:
Early in the season, before they have been rendered wild by being much shot at, I have observed that upon a volley being fired into a flock the unharmed birds in terror sweep around in several circles, and hovering "bunch," as the sportsmen say, over their wounded companions, and sometimes realight with them. At the moment of their hovering in a compact body over the wounded is the time generally seized to fire the reserved barrels; two or three shots will frequently bring down from 30 to 60 birds; and I have known one instance where an officer of the Army bagged 96 birds from one discharge of his fowling piece. After being fired into once or twice the flocks, learning to avoid sympathizing with their dead and wounded, become shy and wary.
Several observers have remarked on the remarkable tameness of the red-backed sandpiper. William Brewster (1925) spent two hours photographing five of these birds within 8 feet of his boat on an open mud flat; they paid no attention to his movements, the click of the camera, or the flapping of the focusing cloth; "during much of the time they were apparently asleep;" he even had difficulty in frightening them away until he splashed water on them. I have frequently walked up to within a few feet of feeding birds and had some difficulty in inducing them to fly more than a short distance.
Their eyesight is keen enough, however, as shown by an incident related by W. E. Saunders (1896). A bird which had been feeding near him for about an hour, stopped, looked steadily, as if afraid, and "shrank down flat on the ground, where he lay perfectly still." After some time Mr. Saunders discovered an eagle approaching, so far away that he could hardly see him. After the eagle had passed the sandpiper resumed his feeding.
Voice.—The red-backed sandpiper is usually silent when on the ground. John T. Nichols, in his notes, calls the "flushing note of a single bird a fine chit-l-it. Its flight note is an emphatic near-whistled chu or chru, resembling some of the calls of the pectoral and semipalmated sandpipers, but quite diagnostic when one is sufficiently familiar with it. This call may also be phonetically suggested by the syllable purre, which is a colloquial name of the European dunlin, of which it is a race."
Doctor Townsend (1905) says: "The note is plaintive and sometimes melodious, and recalls, without its harshness, the cry of the common tern." Mr. Murdoch (1885) and others have noticed that the rolling call, heard on the breeding grounds in June, "reminds one of the notes of the frogs in New England in spring." A bird which Mr. Brewster (1925) flushed "uttered a peculiarly mellow tweet-twel-l-l-ut just as it rose on wing."
Field marks.—In spring plumage the American dunlin deserves the name red backed, for its back is even redder than that of its European relative; at that season the black patch on the belly is very conspicuous, even at a long distance, so that the species is easily recognized. It is a short-legged, rather stocky bird, about the size of the sanderling, and can be identified in the fall by its rather long and somewhat curved bill and its dull, mouse-colored back. A narrow white stripe in the wing can be seen in flight.
Fall.—Of their departure from Alaska, Doctor Nelson (1887) writes: