_Behavior._--The flight of the purple sandpiper suggests at times that of the spotted sandpiper, for when disturbed singly along the shore it is apt to fly out over the water with rapid downward wing strokes and, describing a large semicircle, return to the shore some distance ahead. When flying in a flock the birds are often closely bunched, the whole flock wheeling and turning in unison, showing alternately their dark bodies and their white bellies, in true sandpiper fashion. As a rule they do not make very long flights or fly very high. Their migrations are short and deliberate. They are rather sedentary birds and can generally be found in certain favorite localities all winter and year after year. But, as they show a decided preference for the outer sides of surf-swept ledges, they are not often seen from the land. They can swim almost as well as phalaropes and in calm weather they will often alight on half submerged seaweed or on the surface of the water. Dr. Charles W. Townsend (1905), who watched a flock on an island off Cape Ann, describes their actions as follows: They finally alighted on a steeply sloping rock close to the water's edge on the northeastern point of the island so that they could be watched with binoculars and telescope from the shore. Fifty-eight birds were in sight and there were fully half as many more on the other side of the rock, hidden from view, except when they jumped up from time to time. The flock must have numbered 75. The tide was high and the birds were evidently trying to kill time until low water, when they could gather their food from the seaweed covered rocks. Most of them were resting, squatting on the rock with head to the wind, their dark purplish-gray backs contrasting strongly with their white bellies. Others were slowly raising their wings over their backs, showing the white under surfaces. Again they were chasing each other, making the sleepy ones jump suddenly, or running up the rock to escape an unusually high wave, fluttering with their wings to help themselves. From time to time they were joined by bunches of from 5 to 10 others. _Voice._--This species is a rather silent bird, but John T. Nichols says in his notes: "When about to take wing a flock of purple sandpipers is rather noisy, keeping up a swallowlike chatter, each single-syllabled note suggestive of the _flip_ of the tree swallow and of the _kip_ of the sanderling." _Field marks._--A sandpiper seen on a rocky shore in New England in winter is likely to be a purple sandpiper. Mr. Nichols suggests the following field characters: