In fresh juvenal plumage the crown is "light drab" with "pinkish buff" tips; the sides and back of the neck are deep, rich "cinnamon," deeper and richer than in the adult, shading off, on the upper back, throat, and upper breast, to a suffusion of "pinkish buff"; the chin and belly are white; the color pattern of the upper parts is similar to that of the adult, except that the dark feathers of the back, scapulars, and tertials are tipped with "pinkish buff"; and the greater and median wing coverts are narrowly so tipped.
This plumage is worn through the summer and fall without much change except by extensive fading and some wear. The cinnamon has nearly disappeared in September birds and all the buff edgings have faded or worn away. A body molt takes place in late winter or early spring which produces a first nuptial plumage much like the adult. Young birds can, however, be recognized by the worn primaries and by some of the juvenal scapulars and wing coverts. The first postnuptial molt, the following summer, is complete and produces the adult winter plumage.
Adults have a complete postnuptial molt, beginning in August, and a partial prenuptial molt, beginning in January, which involves the body plumage and some of the scapulars and wing coverts. The "cinnamon" colors of the head and neck are characteristic of the nuptial plumage and are replaced by pale gray in winter adults.
Food.—The feeding habits of the avocet are rather peculiar, as might be expected of a bird with such a peculiar bill. The bill is not so sharply upturned in life, as it is in some stuffed specimens and in some drawings. Dr. Frank M. Chapman (1891) has explained it very well, as follows:
The use of the avocet's recurved bill is clearly explained by the manner in which the bird procures its food. In feeding they wade into the water and drop the bill below the surface until the convexity of the maxilla probably touches the bottom. In this position they move forward at a half run and with every step the bill is swung from side to side sweeping through an arc of about 50° in search of shells and other small aquatic animals. The mandibles are slightly opened, and at times the birds pause to swallow their prey. It is evident that birds with a straight or a downward curved bill could not adopt this method of feeding.
Audubon (1840) describes it, as follows:
They search for food precisely in the manner of the roseate spoonbill, moving their heads to and fro sideways, while their bill is passing through the soft mud; and in many instances, when the water was deeper, they would immerse their whole head and a portion of the neck, as the spoonbill and red-breasted snipe are wont to do. When, on the contrary, they pursued aquatic insects, such as swim on the surface, they ran after them, and on getting up to them, suddenly seized them by thrusting the lower mandible beneath them, while the other was raised a good way above the surface, much in the manner of the black shear water, which, however, performs this act on wing. They were also expert at catching flying insects, after which they ran with partially expanded wings.
Doctor Wetmore (1925) found that, in 67 stomachs examined, animal food amounted to 65.1 per cent and vegetable food 34.9 per cent. Among the animal food were found phyllopods, dragonfly nymphs, back swimmers, water boatmen, various beetles and flies and their larvae. The vegetable matter consisted largely of seeds of marsh or aquatic plants. He says further:
Flocks of the birds search for food scattered about in shallow water, and do not hesitate to swim when necessary in crossing the deeper channels. Frequently a dozen or more feed in company, walking slowly along, shoulder to shoulder, as though in drill formation, at each forward step thrusting the head under water and sweeping the recurved bill along the bottom with a scythelike swing that must arouse consternation among water boatmen and other aquatic denizens of the bays and ponds. At times the writer has observed as many as 300 of these handsome birds feeding thus in a single company, a scene at once spirited and striking. As the birds feed much of the time by immersing the head, anything that may touch the bill is gathered indiscriminately, as in feeding they depend upon the sense of touch. From their manner of feeding, avocets are often scavengers, taking living or recently dead prey without much choice. The large tapeworms found almost without fail in the duodenum of the avocet are transmitted from one bird to another in this manner. The cast-off terminal segments of the worms (bearing the eggs) are picked up and swallowed by other avocets, a proceeding which the writer has personally observed. Avocets also pick up matter floating in the water, on or near the surface, or take insects and seeds from mud bars. The insects may be those living in such localities or may be individuals that have been washed up in drift.