varied, including insects: coleoptera (Otiorhynchus), diptera (larvae of Chironomus), also spiders, Thysanura (or Collembola), annelida and crustacea (Amphipoda, Isopoda, Orchestia, Idotea, Gammarus, and Podocerus) as well as mollusca (Mytilus, Littorina, Purpura, etc.). Vegetable matter is also eaten including algae, grasses, moss, buds, and leaves of phanerogams and remains of cryptogams. Seeds of Cochlearia have been identified and small fish (Gobius) nearly 1 inch long, as well as ova of lumpsucker.
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:
The purple sandpiper is a stockily built bird, which stands low and has a moderately long bill. Its breast and upper parts of a dark purplish gray match admirably the rocks on which it lives, and although darker are not very different in tone from the coloring of the red-backed sandpiper in fall, with which species it might possibly be confused. Both have a white line in the wing shown in flight, but in the purple sandpiper this broadens to a more conspicuous wedge of white backward on the inner secondaries and extends across the bases of the primaries as narrow edging to their coverts, rather than turning the bend of the wing into the primaries. The best field character is the color of legs and feet, which are of a dull but strong yellow, appreciable at a considerable distance. The basal third of the bill is of the same, but tinged with orange.
Fall.—The fall migration of the purple sandpiper is a gradual southward movement along the Atlantic coast. It disappears from its breeding grounds early in September, but the main flight does not reach New England until November or December. What few stragglers have been seen on the Great Lakes were probably migrants from Hudson Bay. E. W. Hadeler writes to me that he observed one on the shore of Lake Erie, Painesville, Ohio, from October 22 to November 12, 1916, and again from October 24 to November 11, 1922. It is interesting to note the uniformity of the dates and the fact that the species was seen always on a stone breakwater, apparently feeding exclusively on the water-washed stones.
Winter.—The purple sandpiper is the "winter snipe" of the New England coast, where flocks of from 25 to 75 or more may be found regularly on certain outlying rocky ledges. Here they seek shelter among the rocks from the flying spray and from the wintry blasts; and here they find their food washed up by the waves or hidden in the half floating beds of rockweed. On December 10, 1913, while we were shooting eiders on one of the outer ledges in Jericho Bay, Maine, a flock of about 50 of these hardy little birds seemed out of place in our rough surroundings. It was a cold, blustering day; the surf was breaking over the rocks and the sea was white with combing breakers; even the hardy sea ducks sought the shelter of the ledges; but these plump little birds seemed quite happy and contented as they huddled together in a compact flock on the slippery rocks. They were very tame and confiding; even the reports of our guns served only to make them circle out around the ledge a few times and then return to its shelter. Evidently this was their winter home. We did not have the heart to shoot any of them.
Mr. Nichols tells me that "very occasionally in winter, early spring or late fall, one finds single birds on the sandy beaches of New York or New Jersey south of the rocks."