The red-backed sandpiper is one of the most abundant shore birds inhabiting the Hooper Bay region, confining itself almost entirely to the low-lying flats. The Eskimos first reported this hardy species on May 10 and two days later we collected our first specimen at Point Dall. They were common in loose flocks by May 15 and abundant by May 20. At that time they were often associated with the Aleutian sandpiper, to which, in the field, they bear a marked resemblance. Soon after the later date the flocks disintegrated into mated couples and they then repaired to their lowland breeding haunts.
Courtship.—Dr. E. W. Nelson (1887) gives an attractive account of the courtship of this species, as follows:
Soon after they arrive in spring they are engaged in pairing, and the males may be seen upon quivering wings flying after the female and uttering a musical, trilling note, which falls upon the ear like the mellow tinkle of large water drops falling rapidly into a partly filled vessel. Imagine the sounds thus produced by the water run together into a steady and rapid trill some 5 to 10 seconds in length, and the note of this sandpiper is represented. It is not loud but has a rich full tone, difficult to describe, but pleasant to hear among the discordant notes of the various waterfowl whose hoarse cries arise on all sides. As the lover's suit approaches its end the handsome suitor becomes exalted, and in his moments of excitement he rises 15 or 20 yards, and, hovering on tremulous wings over the object of his passion, pours forth a perfect gush of music, until he glides back to earth exhausted, but ready to repeat the effort a few minutes later. The female coyly retreats before the advances of the male, but after various mishaps each bird finds its partner for the summer and they start off house hunting in all the ardor of a rising honeymoon.
Mr. Brandt in his manuscript notes describes it a little differently, thus:
The red-backed sandpiper, often called the American dunlin, arrives in flocks, the individuals of which are apparently not all mated. A female will jump up and be immediately pursued by two to five males, and as they all twist about, in and out, twittering all the time, the alternate flashing of their reddish backs and black lower parts seems like the signals of the telegraphic code. The males appear never to catch the females, but to try to keep as close to them as possible. When they alight again in the flock whence they started they at once resume feeding without further display. The thrilling song of this dainty bird is delivered while hovering with quivering wing beats in mid-air. It appears as if both male and female carry on the vocal effort, which sounds something like the cheery tinkling of ice in a glass, and ends with a real lover's note dear, dear, dear. This is repeated again and again and is one of the pleasant characteristic songs of the marshy grass-woven flats, where the discords of waterfowl prevail. After the fastest male has captured his elusive sweetheart the two retire to their chosen place on the flats to take up their more serious duties. Here the female lays her eggs, often in a situation that is moist, and never very far from a small pond or slough.
Nesting.—The same observer says of the nest:
The home of the red-backed sandpiper is almost always found on a dry eminence in the widespread grassy tidelands, where, near some pool under the damp matted vegetation of the previous year, sufficient concealment is afforded. Here in a mere depression in the ground, still frozen underneath, a fragile nest is hurriedly made of dry grass stems and filled, rather than lined, with the tiny crisp leaves of the berry-bearing plants, that are deposited by the flood tides of autumn in this area. The range of measurements of 25 nests is: Inside diameter, 3½ to 4 inches; inside depth 2 to 3 inches; total depth, 3 to 5 inches.
This sandpiper is among the early nesters, we having taken the first completed set of eggs on May 29, while by June 1 we had discovered 75. The middle of June found the downy young bursting forth, dainty creatures clad in black and brown with markings similar to those of the other sandpiper chicks.
Dr. Joseph Grinnell (1900) found this species breeding on the Arctic coast of Alaska, about 20 miles northeast of Cape Prince of Wales, on June 27 and 28; he writes:
The birds were found scattered out on the tundras whence they could be flushed from their nests or from where they had been feeding. One nest was a cup-shaped cavity slightly lined with grasses and sunk into the top of a hummock of moss surrounded by marshy ground. The two others found were similarly located except that they were embedded in clumps of grass, and mostly hidden from view by the surrounding blades. Each nest contained four eggs. One was fresh but the other two were considerably incubated.