In the marshes—which are their preferred feeding grounds, although, as stated above, they are sometimes found on the beaches, especially in the spring—they scatter widely, and one may flush one bird after another, previously unseen in the grass. They soon unite in a flock, however, and after circling about and turning now this way, now that, with great nicety of evolution, drop down again suddenly, often near the spot from which they sprang. A single bird flushed generally darts off in irregular zigzags, very much after the manner of a Wilson snipe, calling as it goes.
In feeding in marshes they frequent the short grass and also the open sloughs or mud holes. Here they snap up insects or probe diligently for larvae in the mud and shallow water. They are fond of the mud and sand flats in the tidal estuaries at low water where they appear to find plenty of food, and they run about on the eel grass. In all these places they spread out in an irregular fashion when feeding. Such gluttons are they that they are generally loaded with fat on the southward migration and they are often very fat in the spring. Notwithstanding this, their wind seems to be excellent and their flight as swift. They are fond of bathing like most birds, and of this Mr. Nichols writes in his notes as follows:
It squats in shallow water, ducking the head under, throwing the water back and fluttering the wings, and at the end of the bath jumps an inch or two into the air with a flutter, apparently to shake the water out of its feathers. Afterwards it usually stands quietly and gives its plumage a thorough preening.
Voice.—The nuptial song has been described under courtship, but the bird has also a variety of call notes from a simple weep or peep, from which, doubtless, it gets its common name, to a succession of notes more or less complicated. John T. Nichols (1920) has written at length on the voices of shore birds, and has kindly furnished the following for this article:
The identification flight-call is a loud diagnostic kreep, distinguished by the ēē sound from any note of the semipalmated sandpiper.... In flushing, a least sandpiper sometimes utters a string of short unloud notes with or without the ēē sound, quee-quee-quee-que or queque to be followed almost immediately by some variation of the flight call, as it gets more fully under way. The flight note varies down to a che and cher, not readily, if at all, distinguishable from similar calls of the semipalmated sandpiper.... When a flock are up and wheeling about a feeding spot to alight there again almost at once, they have sometimes a confiding little note chu chu chu chu, etc. It has also a whinny, a little less clearly enunciated than that of the semipalmated but almost identical with the same.
Field marks.—The small size of the least sandpiper distinguishes it readily from all the other sandpipers in this country except the semipalmated, with two exceptions to be noted later. As the least is more frequently found on tidal flats in the estuaries and in salt marshes, it is sometimes called the "mud peep," while the semipalmated, which especially delights in the sand beaches is called the "sand peep." Unfortunately this rule, although of general value, is far from absolute, and the birds often exchange places. The least sandpiper is more often found on the beach in the spring than in the fall. The semipalmation is, of course, a diagnostic mark in the hand, but only under exceptional circumstances can it be seen in the field. The color of the tarsus, however, is distinctive and can be made out in favorable light at a considerable distance. I have always thought it absolutely distinctive, but the published descriptions and plates of these two birds are often inaccurate. I have, therefore, compared the legs of both these species, freshly collected, with Ridgway's (1912) "Color Standards and Color Nomenclature." In the semipalmated sandpiper the tarsi of the adults are black and this is also the case in the juvenals except that there is a slight greenish tinge to be seen on close inspection. In the adult least sandpiper the tarsi are distinctly yellow with a faint greenish cast. They correspond best to the sulphine yellow of Ridgway, while the toes, which shade off a little darker, are citrine. In the juvenal, there is more of a greenish tinge, and I have put the tarsi down as oil yellow, the toes shading into yellowish oil green. In deciding on these colors I have had the advice of an artist. The richer brown plumage of the back and the darker streakings and wash of the breast help to distinguish the least from the lighter and grayer semipalmated bird, but in the fall these distinctions are less marked in the adult. Even at this season, however, a least sandpiper on the beach in a flock of semipalmated stands out by its browner colors, and, in the marsh, a semipalmated in a flock of least looks very gray. The least sandpiper is a little smaller than the other bird, but this character as well as the color of the plumage are of slight value without the presence of both birds for comparison.
Another point, which at times can be satisfactorily made out in the field, is that the bill of the least sandpiper is slightly decurved, while that of the semipalmated is straight and stouter. It has been noted by Coues (1861) and by others independently, that the least sandpiper is a perfect miniature of the pectoral sandpiper even to the color of its legs. The great difference in size, however, prevents any confusion.
Two other sandpipers, referred to above, may, however, be mistaken for least or semipalmated sandpipers, although they are somewhat larger. Gunners at Ipswich used to call them "bull peep." I refer to the white-rumped and the Baird sandpipers. The white rump of the former is diagnostic and is easily seen in flight, but is generally covered by the wings when the birds are running on the sand. The plumage of both Baird and white-rumped sandpipers is dark in front of the bend of the wing, while in the semipalmated and juvenal least it is light. This is a fine point that I have found of great value.
Fall.—The last migrant for the north has scarcely gone before wisps of returning sandpipers appear. The regular northward migration in Massachusetts ceases about June 7, although an occasional nonbreeding bird may remain, and the migrants begin to return about July 4. A surprisingly large number of early fall migrants appeared at Ipswich on July 3, 1911. A flock of at least 50 whirled about and alighted near me on the marsh. One must suppose that the early migrants in the spring are the early ones to return in the fall. They are generally all gone from the New England coast by the end of the first week in September, although stragglers may be found in October. They migrate both by day and by night.
Carl Lien writes in his notes from Destruction Island, Washington, that the least sandpiper—