Nesting.—We found no large breeding colonies in Saskatchewan but several small ones. The Hay Lake colony referred to above was perhaps the largest, containing 15 or 20 pairs. The nests, found here on June 15, were merely slight hollows in the sun-baked mud on the broad alkali flats bordering the shallow lake; they were scattered widely among the little tufts of short grass which scantily covered the flat; the hollows measured from 3 to 4 inches in diameter and were lined with a few dry grasses. Some of the nests were well formed and somewhat elevated. Although in plain sight, the eggs were not easy to find, as they matched their surroundings perfectly.
On June 14, 1906, we found an interesting little colony of avocets on an island in Big Stick Lake, Saskatchewan, which was also occupied by big colonies of California and ring-billed gulls, common terns, a few spotted sandpipers, and a few pairs of ducks. The avocets, terns, and sandpipers were all at one end of the island, a low grassy point; the ring-billed gulls and ducks were in the central, highest part; and the California gull colony was at the other end. The avocets' nests, ten or a dozen of them, were placed in the short grass near the edge of the beach or on the drift weed lying in windrows on the beach; one nest was partially under a fallen shrub or bushy weed. The nests were made of grasses, weed stems, straws and small sticks, with sometimes a few feathers, loosely arranged around small hollows, from 5 to 7 inches in diameter. Two of the nests held five eggs, the others three or four.
Robert B. Rockwell (1912) found an interesting colony of avocets on an island in Barr Lake, Colo., of which he says:
The nests were all located in very similar locations, among a young growth of cockle burrs not over six inches in height and which had probably grown at least half of that since the eggs were laid. The cockle burrs formed a belt about 10 yards wide clear around the island just below the dense blue-stem and other rank grass with which the Island was covered and on ground that was under water during the high water of the spring although inundated for a short time only. Two of the nests were very crude affairs, being a mere shallow hollow in the sand with a very few dead weed stalks of short lengths arranged around the eggs. The other was constructed in the same manner, but was quite well lined with weed stems, so that the eggs did not touch the ground. There was no evident attempt at concealment, the nests all being placed in small open spaces from six inches to a foot in diameter, and with nothing to protect them; but the color of the eggs was sufficient protection to make them quite inconspicuous.
Dr. Alexander Wetmore (1925) writes:
The sites chosen often are subject to inundation by sudden floods, when the birds scurry about, seemingly in confusion, but in reality working actively to build up the nest in order to support the eggs above the level of the encroaching water. In some cases it may be necessary to erect a structure 12 or 15 inches in height. Weeds, small sticks, bones, or dried bodies of ducks or other birds, feathers, or any other materials available are utilized as building materials.
Eggs.—The American avocet lays three or four eggs, usually four and occasionally five. Numerous nests have been found containing seven or eight eggs, but these are probably products of two females. Edwin Beaupré writes to me that, in a colony of five pairs found by him on an island in a small lake in southern Alberta, the five pairs were occupying three nests; one contained eight eggs, another seven and the third four. The eggs vary in shape from ovate (rarely) to ovate pyriform and they are usually much elongated. The shell is smooth, but not glossy. The ground color varies from "Isabella color" to "deep olive buff." This is more or less evenly covered with irregular spots and blotches, in various sizes, of brownish black, blackish brown, or black, rarely "warm sepia" or "bister"; there are occasionally a few blackish scrawls, and numerous underlying spots of various shades of drab. The measurements of 55 eggs average 49.8 by 34 millimeters; the eggs showing the four extremes measure 56.3 by 34.6, 51.5 by 36.6, 43.2 by 33.4 and 47 by 31 millimeters.
Young.—The period of incubation of the American bird has apparently not been determined, but that of the European bird is said to be 28 days. I have no data as to how the sexes incubate. Young avocets are very precocial and leave the nest soon after hatching. They are expert at hiding, even on the open flats and beaches; and they take to the water at an early age, where they can swim and dive like young ducks. I have seen a brood of four young, that could not have been hatched more than a few hours, swimming out in a lake, as if very much at ease. They soon learn to tip up in shallow water and probe on the bottom, like their parents, for their insect food.
Plumages.—The downy young avocet is well colored for concealment on an open beach or alkaline flat. The colors of the upper parts are "cinnamon buff," "cream buff," and buffy grays, lightest on the crown and darkest on the rump; there is a distinct but narrow loral stripe of black; the crown is indistinctly spotted with dusky. Two parallel stripes of brownish black distinctly mark the scapulars and two more the sides of the rump; the wings, back, rump, and thighs are less distinctly spotted or peppered with gray and dusky. The under parts are buffy white, nearly pure white on the throat and belly.