The semipalmated sandpiper flies high into the air, often almost out of sight, and pours forth a sustained tinkling song, which sounds like its native name uttered as a high-pitched trill—"la-v-la-v-la-v." As it sings it rapidly fans the air with short wing beats, at the same time moving at considerable speed continuously back and forth over a distance of 50 yards or more. Four of the birds which I took to be males were rather noisy, twittering, and purling, and occasionally one of them rushed at another as if he seriously intended to wage mortal combat. The feathers on his dainty neck stood out in an angered ruff; his wings were half spread, showing their light markings; and when the little warrior was just about to strike he folded his wings and elevated his tail until it was almost vertical above his long wing tips. There was, however, no real fight, for each one seemed to know his superior and gave way, after a little display, like a weaker rooster in a well-regulated barnyard.
Nesting.—H. W. Brandt contributes the following:
The semipalmated sandpiper nests amid the short herbage on the grassy dunes near the moaning breakers of Point Dall, where it selects a site quite exposed to view. Among the creeping berry vines the bird simply scratches a depression in the sand, and this it lines with a few disconnected grass stems, stiff moss stems, and a handful of tiny, crisp-dried leaves of the cranberry, willow, or dwarf birch. The range of measurements of five nests is: Inside diameter, 2 to 2½ inches; inside depth, 1½ to 2 inches; total depth, 2½ to 31/4 inches. The nest is very fragile and breaks up at once if disturbed. Like all shore birds that nest in the open, the brooding bird is anything but a close sitter, and in consequence the nest must be found by diligent search. An incubating female was collected as it departed from the nest.
Roderick Macfarlane, who found many nests of this species in the Barren Grounds, describes two of them as follows:
Nest was found between two small lakes—a few withered grasses and leaves in a shallow hole or depression, partly shaded from view by a tuft of grass. The nest was a mere depression in the midst of some hay and lined therewith, as well as with a few withered leaves.
Winthrop Sprague Brooks (1915) relates his experience in Alaska as follows:
Thirteen nests were found, the first, a set of three fresh eggs, being taken on June 12. All the nests were essentially alike—mere cavities in damp tundra close to a pool, and lined with dry willow leaves. On seven nests the female was found, and the male on six. Although the male seems to take about an equal share in brooding on the eggs and taking care of the young, I could not see that he did this at any particular time, for I could find either sex on the nest at midnight or midday. Neither sex showed any more concern than the other when an intruder was at the nest. In most cases the bird disturbed would flutter along a few yards and then remain walking quietly and watching. On one occasion a female made a great disturbance. Semipalmated sandpipers on the breeding ground are the most gentle and interesting birds of the North.
Eggs.—[Author's note: Four eggs seems to be the invariable rule with the semipalmated sandpiper. They are usually ovate pyriform in shape with a tendency to become subpyriform. The shell is somewhat glossy. The eggs can not with certainty be distinguished from those of the least sandpiper on one hand or the western sandpiper on the other hand; the measurements overlap with both and the colors and markings intergrade with both. I have 11 sets of semipalmated, and I can match nearly every one of them with sets from my series of the other two species. In series, however, they much more closely resemble the least sandpiper.
Herbert W. Brandt has sent me a description of his sets taken in Alaska, which are probably of the normal type, as follows: