The actions of different pairs of stilts when their nesting colonies are invaded are also variable. Sometimes a flock of noisy screeching birds will press close about the intruder, some hanging in the air on rapidly beating wings, others bouncing along the ground by leaps and bounds, raising and lowering their wings continually; while others go through every conceivable motion both on the ground and in the air. It seems that the larger the colony the more demonstrative the birds are; for in several instances where only one or two pairs were breeding the female would sneak from the nest in a guilty manner and quietly join her mate on the opposite side of the pond, where they would remain almost motionless or feed nervously along the margin of the pond.
Eggs.—Four eggs are usually laid by the black-necked stilt, sometimes five, rarely seven, and occasionally only three. The shape is ovate, often somewhat pointed, and there is little, if any, gloss. The ground color is dull "honey yellow," with an olivaceous tinge, or "cream buff." The eggs are irregularly spotted or covered with small blotches of brownish black or black. Sometimes there are a few blackish scrawls and usually a few underlying small spots of drab. They are often stained with mud. The measurements of 75 eggs, in the United States National Museum, average 44 by 30.5 millimeters; the eggs showing the four extremes measure 48 by 30, 47 by 32, 40.5 by 30, and 46 by 28 millimeters.
Young.—Incubation is shared by both sexes, but we have no accurate information as to its duration. Mr. Dawson (1923) says:
The infant can make shift to shuffle away from the nest and into cover within the hour, if need be, but he can not negotiate his stilts until several hours have elapsed after hatching; and he feels decidedly pale and tottery, like a young colt, until the day after.
Dr. Frank M. Chapman (1908) writes:
On May 23, their eggs were hatching, and in June the snipelike young were widely distributed over the marsh. They invariably attempted to escape observation by squatting with neck outstretched, but the parents, whether one approached their eggs or young, expressed their solicitude by a surprising extravagance of motion, all apparently designed to draw attention to themselves. I was at times surrounded by hopping, fluttering stilts, all calling loudly, waving their wings, bounding into the air to hang there with dangling legs and beating pinions, and executing other feats which would have done credit to acrobatic marionettes.
Dr. Alexander Wetmore (1925) says:
The young grow rapidly, and the increase in the length of their legs is amazing. Until the bones are well formed the young, when not feeding, prefer to rest with the full length of the tarsus extended on the ground, but even then appear as tall as other shore birds of similar body size. Stilts show considerable attachment for their young, and, unless dispersed by some untoward accident, frequently remain in family groups long after the young are able to care for themselves. As the latter become strong on the wing the family parties range over the country in search of suitable feeding grounds. As the nights grow cold in the North the birds band together in larger flocks and finally on some moonlit night in September, young and old may be heard calling as they pass overhead on their southward migration.