P. H. Bahr (1907) throws some light on the peculiar sexual relations of this species; he says:
On the 5th of June we watched the phenomena of polygamy, and of attempted polyandry in this species. At one end of the loch the former condition held sway, two energetic and quarrelsome females having attached themselves to one miserable-looking male, and it was ludicrous to behold the awe in which he held them. Once in particular he nearly swam between my legs in his efforts to avoid their attentions. Till our departure on the 27th, these three birds were constantly to be seen together. At the other end of the loch two males were seen continuously circling round the head of a female. I frequently observed the male performing evolutions, which I have previously described as the "marriage flight." Zigzagging from side to side with amazing rapidity he would hover with dangling legs over the head of the female, who, circling placidly in the water, appeared to take no notice of his attentions. Then settling beside her he would peck and chase her as if endeavoring to make her take to flight. Failing in this he would dash off once more across the marsh uttering a warbling sort of song much like that of the ringed plover. Then he would settle in a reedy spot, such as would be chosen for the nesting site, and would call vigorously, looking always in the direction of the female, as if expecting her to follow. I observed several pairs, behaving in this manner, and such was their fervor that the males continued this performance even in the midst of one of the worst storms we experienced. Often the female would resent these attentions, and a pitched battle would ensue.
Herbert W. Brandt (mss.) writes:
It is very interesting to watch a struggle between two female northern phalaropes over a solitary male. They fight by the hour, not after the manner of the males, which rush at each other and boldly lock in a mortal combat, but rather these females fight by flipping their wings and pecking at each other instead of laying hold with determination. This can be likened only to a feminine hair-pulling episode. One day I watched such a combat for an hour, and there were numerous occasions on which I thought that one of the birds would succumb; but the contest seemed to be very equal, and when a bird recovered from a hard onslaught it would return at once and take up the wing sparring. They would flutter here and there over the ground, first one then the other attacking, closely followed all the time by the shy but neutral male, the prize of the conflict. Natives informed me that they had never known of one's being killed by the other, but that the birds would fight all day long.
Nesting.—My personal experience with the nesting habits of the northern phalarope has been limited to what few nests we found in the Aleutian Islands in 1911. These birds were very scarce or entirely absent in the eastern half of the chain. We saw a few on Atka Island where several nests, with fresh eggs or incomplete sets, were found on June 18. On Kiska Island they were really abundant and we found them breeding about the small grassy ponds and wet meadows; fresh eggs were found on June 21. Their favorite resorts all through the western part of the chain were the wetter portions of the flat alluvial plains, near the mouths of the streams and about the marshy ponds. They were very tame everywhere and, about the ponds where they were breeding, they were very solicitous and noisy. Their simple nests were merely deep, little hollows, lined with a few bits of grass, in the little mounds or tussocks in the wet meadows around the borders of the ponds or near the small streams.
F. S. Hersey collected several sets of eggs for me near St. Michael, Alaska, in 1914 and 1915; most of the nests were in rather wet situations on the tundra, in or near marshy places, rather poorly concealed and scantily lined with grasses; others were well hidden in the clumps of scanty grass, or deeply sunken into the tundra mosses and lined with bits of leaves or well lined with grasses. Other observers have described the nesting habits of this species substantially as indicated above, except that Henry H. Slater (1898), who has "encountered 45 nests with eggs in them in one day, and considerably more than a hundred altogether", describes the nest as "a deep comfortable cup, concealed in a tuft of grass, or under a trailing branch of some dwarf Arctic shrub."
Eggs.—The northern phalarope lays four eggs almost invariably, rarely three eggs constitute a second set; as many as five and even seven eggs have been found in a nest, the largest number being the product of two females. The eggs vary in shape from subpyriform to ovate pyriform, are slightly glossy and are very fragile. The prevalent ground colors range from "pale olive buff" to "dark olive buff" or "ecru olive;" "olive buff" seems to be the commonest shade. In richly colored sets the colors range from "Isabella color," or "Dresden brown" to "buckthorn brown;" and in light buffy sets from "cream buff" to "cream color." The size, type, and arrangement of markings vary greatly in endless patterns. Some eggs, perhaps only one in a set, are evenly covered with small spots or dots, but more often these are mixed with larger, irregular spots or blotches. Some eggs are boldly marked with large irregular blotches. The colors of the markings range from "sepia," or "warm sepia," and "bister" to deep blackish brown, depending on the depth of the pigment. The underlying spots, in various drab shades, are small, inconspicuous and not numerous. In my series of over 50 sets there are two abnormal eggs; one is plain bluish white and unmarked; and another is similar except for one large blotch of "sepia" covering the large end. The measurements of 119 eggs, in the United States National Museum, average 29 by 20 millimeters; the eggs showing the four extremes measure 33 by 21, 28 by 22.5, 27 by 19, and 31 by 18.5 millimeters.
Young.—The period of incubation does not seem to be definitely known, but probably it is not far from 21 days. A set of four eggs found by H. B. Conover on June 10 hatched on the evening of June 30. Incubation is performed largely, but perhaps not wholly, by the male. H. H. Slater (1898) writes: