The main breeding grounds of the sanderling are probably on the more northern Arctic islands, but not enough nests have ever been found anywhere to produce the hosts of birds which we see on migrations. Col. H. W. Feilden (1877) gives the following description of his discovery of the nest of this species:
I first observed this species in Grinnell Land on the 5th of June, 1876, flying in company with knots and turnstones; at this date it was feeding, like the other waders, on the buds of Saxifraga oppositifolia. This bird was by no means abundant along the coast of Grinnell Land, but I observed several pairs in the aggregate, and found a nest of this species containing two eggs in latitude 82° 33' N. on June 24, 1876. This nest, from which I killed the male bird, was placed on a gravel ridge, at an altitude of several hundred feet above the sea, and the eggs were deposited in a slight depression in the center of a recumbent plant of Arctic willow, the lining of the nest consisting of a few withered leaves and some of the last year's catkins. August 8, 1876, along the shores of Robeson Channel, I saw several parties of young ones, three to four in number, following their parents, and led by the old birds, searching most diligently for insects. At this date they were in a very interesting stage of plumage, being just able to fly, but retaining some of the down on their feathers.
The best account we have of the home life of the sanderling is given to us by Mr. Manniche (1910), who found this species to be one of the commonest breeding birds in northeastern Greenland. He writes:
In the extensive moor and marsh stretches west of Stormkap are many smaller stony and clayey parts lying scattered like a sort of islands. As these "stone isles" are most restricted in size, I could without special difficulty realize the existence of the birds here, and I found several nestling sanderlings on such places. The problem was decidedly more difficult to me when the birds had their homes on the extensive table-lands farther inland; here it will depend on luck to meet with a couple of nestling sanderlings.
The laying began about June 20. The first nest found containing eggs dates from June 28; these had, however, already been brooded for some days. The clutch of eggs latest found dates from July 15; the eggs in this nest were very much incubated. The sanderling places its nest on the before mentioned dry clay-mixed stony plains sparsely covered with Salix arctica, Dryas octopetala, Saxifraga oppositifolia, and a few other scattered low growths. I only found the nest on places of this type, never on moors or plains entirely uncovered. The larger or smaller extent, the higher or lower position over the level of the sea and the distance from nearest shore of such locality is, according to my experience, of no consequence. It only seems, as if the sanderling prefers to nest on such places, which are situated not very far from fresh water—a lake or a pond—to the shores of which the young ones are often directed. Some nests found prove, however, that the birds do not insist upon this.
The situation of the nest is also extremely constant. At the edge—or rarer farther in—of a tuft of Dryas, the bird will form a cup-shaped not very deep nest hollow, the bottom of which is sparsely lined with withered leaves of Salix arctica or other plants growing in the neighbourhood. In size, and partly in shape the sanderling's nest resembles that of Tringa alpina. The striking likeness in color to the surroundings and the monotonous character of the landscape makes it extremely difficult to find the nest unless the bird itself shows the way to it. The number of eggs in a clutch is always four. I found eleven nests with eggs and some fifty hatches of downy young ones but none of these differed from the normal number.
By excellent tactics the breeding female understands to keep secret the hiding place of the nest. She will generally leave the nest so early and secretly, that even the most experienced and attentive eye does not perceive it. She rushes rapidly from the nest with her head pressed down against her back executing some peculiar creeping movements quite mute, and hidden between stones and plants; following natural hollows in the ground she will first appear in a distance of at least 100 meters from the nest. By means of short, snarling, and faint cries and now and then by flying up, she will then try to turn one's attention to herself. She will often settle for some moments on small stones, clods of earth, and similar places, from which she again will rush away with her dorsal feathers erected and her wings hanging down and always in a direction opposite to that in which her nest is situated.
H. E. Dresser (1904) gives a translation of notes on this species made by Dr. H. Walter in the Taimyr Peninsula, from which I quote as follows:
The nests, found late in June and early in July, contained four eggs each in three cases and three eggs in one case. The nest was placed, unlike that of the other waders, which affected the grass-covered portions of the tundra, between bare clay lumps on moss, and consisted of a shallow depression lined with a few dry straws and a white tangle. In two cases the male, and in two the female, was incubating. On the 16/29 July, when the young in down were taken, the male showed anxiety, but the female was not seen. During the breeding season some of these birds wandered about in small flocks. This species remained until the end of August.
Eggs.—The sanderling lays four eggs, sometimes only three. The eggs are very rare in collections and few are available for study, but they have been well described and fully illustrated. The eggs taken by Doctor Walter are described by Mr. Dresser (1904) as follows:
Blunt pyriform, fine grained, with a faint gloss. Ground color pale yellowish white, with a very pale greenish tinge and somewhat marked with small yellowish brown and dark brown spots; a few indistinct light violet gray markings; at the larger end a few blackish dots and streaks.