A set in the United States National Museum is thus described for me by J. H. Riley:
No two eggs in this set are alike. They vary in ground color from a little darker than "citrine drab," through "light brownish olive," to "dark olive buff." The darkest egg has a zone of "olive brown" spots at the larger end, with a few "clove brown" dots here and there, and a few scattered spots and blotches of "olive brown" over the rest of the egg. The next darkest egg is similar, but with the contrast between the ground color and the "olive brown" zone more pronounced and an increase in size and number of the "clove brown" spots. The lightest ("dark olive buff" ground) egg has a solid cap of "clove brown" at the larger end and quite numerous blotches, scrawls, and spots of "clove brown" and "olive brown," with a few shell markings of "drab" over the rest of the surface.
Some of the eggs I have seen are much like well-marked eggs of the black-tailed godwit. The measurements of 27 eggs average 55.2 by 38.1 millimeters; the eggs showing the four extremes measure 60.6 by 39.6, 56 by 41.2, and 51 by 35 millimeters.
Plumages.—I have never seen a downy young Hudsonian godwit nor any very young juvenals. The sexes are alike in the juvenal plumage and probably all through the first year. The plumages are alike in winter but the females are somewhat larger. A young female in juvenal plumage, taken in Maine in September, is similar to the winter adult, except that the crown is more streaked with dusky; the feathers of the mantle are "sepia," edged with "pinkish cinnamon"; the scapulars and tertials are edged, notched, or barred with "cinnamon," and the tail is tipped with buffy white. I have seen birds in this plumage up to October 13; but usually the partial postjuvenal molt of the body plumage and probably some of the scapulars and tertials begins in October. Material is lacking to illustrate the first prenuptial molt, which takes place in South America. Probably this molt is very limited in young birds. A female, taken on May 28 in Wisconsin, probably in first nuptial plumage, shows a mixture of fresh adult nuptial body feathers both above and below, and fresh tail feathers, but the primaries are worn. Probably at the next molt, the first postnuptial, which is complete, the adult winter plumage is assumed.
Adults have an extensive prenuptial molt, involving everything but the wings and perhaps the tail. This is accomplished during the late winter or early spring before the birds migrate. Dr. Alexander Wetmore (1926) says:
A male shot March 7 is in full winter plumage with worn primaries but newly grown tail feathers and lesser wing-coverts. Two females shot March 8 have renewed the flight feathers and tail and have the breeding plumage growing rapidly on the body.
The postnuptial molt is complete; the body molt begins in July and is well advanced towards completion when the birds reach our shores in August or September; the wings are apparently molted later, after the birds reach their winter homes in South America. There is a striking difference between the richly colored nuptial plumage and the dull and somber winter plumage, with the brownish gray upper parts and the pale grayish buff under parts.
Strangely enough, all the recent manuals that I have seen state or imply that the sexes are alike in nuptial plumage; and this in spite of the fact that many years ago Swainson and Richardson (1831) called attention to the striking difference between the two sexes, which are decidedly unlike. In the male the underparts are deep, rich brown, "Mikado brown" or "Kaiser brown," with much individual variation in the amount of black transverse barring, which is sometimes almost entirely lacking in the center of the breast. In the female, which is always somewhat larger, the under parts are barred with white, dusky, and brown; the feathers of the flanks are brown with three or four black or dusky bars and broad white tips; on the breast only the outer half of the feather is brown, the remainder is white, with two or three dusky bars and a broad white tip. Careless sexing may have caused the oft-repeated error.
Food.—Edward H. Forbush (1925) says that "the food of the Hudsonian godwit includes worms, many insects (including horseflies and mosquitoes), mollusks and crustaceans, and various small forms of marine life."
Behavior.—He also says: