All these observations were made on birds that were both incubating and singing. On one occasion only did he see two birds together.
This flight song piped overhead and was sung over and over again with a tremulous zest. Alternating with it, was repeated for long intervals an excited call of two notes. We glanced up and for the first time beheld two adult least sandpipers together. Alternately they flapped and soared and circled about in rapturous fashion. For several minutes the alternation of song and call continued without break of any kind. Sometimes the song was given three times consecutively and followed by as many as 30 or 40 repetitions of the call, this in turn to be followed by the song again.
W.E. Saunders (1902) has recorded the courtship as observed by him at Sable Island. He was there between May 16 and 23, too early for nesting. He says: "I found them invariably in pairs, evidently mated, and often sitting so close together that two could be obtained at a single shot if desired." To his ear the song notes resembled somewhat those of the spotted sandpiper. He says of the courtship flight:
Sometimes both birds would be in the air at once, but whether the female gave the note as well as the male, I could not definitely ascertain without shooting the birds, which I was very loath to do. The note would be given continuously for perhaps three or four minutes, during which time the bird flies slowly with steady flapping of the wings, mounting in the air gradually until, when watching them in the evening, one loses sight of them in the gloom.
Nesting.—The least sandpiper makes its nest either in wet grassy or sphagnum bogs close to a pond or tidal water; or on dry uplands, often among low bushes. In either case the nest is a simple affair. P.B. Philipp (1925) describes its method of construction as observed by him in the Magdalen Islands:
The bird picks out a spot in the wet moss of a bog or in the dry leaves of a ridge, and scratches a shallow hollow in which it sits, and, by rapidly turning, molds a depression of the required depth. Which of the pair does this I have never determined, but the other bird is usually present, standing close to the nest-builder and offering encouragement by a low, rapid twittering.
The nest depression in the moss is generally lined with dry leaves, although these may be very few in number, and a little dried grass. The internal dimensions of the nest as given by Audubon (1840) are: Diameter, 2½ inches; depth, 11/4 inches.
J. R. Whitaker writes, in his notes on these birds at Grand Lake, Newfoundland, that the nest is nearly always amongst a labyrinth of pools of water, and is usually on the side or the top of a hummock of sphagnum moss, but I have found them on flat ground amongst reindeer moss. When on a moss hummock, the scratch is about 2 inches deep and there is always an inch or so of material in the bottom usually composed of cranberry leaves and short bits of cotton grass stems.
Eggs.—[Author's note: Four eggs is the rule with the least sandpiper. They vary in shape from ovate pyriform (the usual shape) to subpyriform, and they have only a slight gloss. The ground colors vary from "deep olive buff" to "pale olive buff," or from "pale pinkish buff" to "cartridge buff." There are two extreme types of markings, the boldly blotched and the finely sprinkled type, with many intergradations between them. Some eggs are more or less evenly covered, usually more thickly about the larger end, with a mixture of dots, small spots, and small, irregular blotches. In some the blotches are larger, more elongated, often spirally arranged and often confluent at the larger end. In still others the whole egg is evenly covered with very fine dots and small markings. There are two sets from Labrador of the latter type in my collection; one has a pinkish ground color, covered uniformly with a fine sprinkling of reddish brown markings, exactly like certain eggs of the western sandpiper; the other set is similarly marked, but the ground color is "olive buff" and the markings are in darker browns. At the other end of the range of variation I have a particularly handsome egg, which has an "olive buff" ground color, with a few large splashes of "vinaceous drab," overlaid, chiefly around the larger end, with a few great splashes of "liver brown," "chestnut brown," and "bone brown." The ordinary markings are in various shades of dark, rich browns, "bay," "liver brown," "chestnut," and "hazel," deepening to blackish brown where the pigment is thickest. The underlying spots are in pale shades of "vinaceous drab." The measurements of 65 eggs in the United States National Museum average 29 by 21 millimeters; the eggs showing the four extremes measure 31 by 21, 30 by 22, 26.5 by 20, and 28 by 19 millimeters.]
Young.—Incubation is believed to be performed largely by the male. Mr. Philipp (1925):