Life histories of North American shore birds, Part 1 (of 2)Bent, Arthur Cleveland
Science
Life histories of North American shore birds, Part 1 (of 2)
Bent, Arthur Cleveland
Birds -- Behavior; Shore birds -- North America
Upper parts light buffy grayish mottled with dusky, the back and
rump with several large blotches of black; head, neck, and under
parts buffy whitish or brownish white, the crown, occiput, and hind
neck grayish, the crown with a mesial streak of black, the occiput
with several irregular spots of the same.
The juvenal plumage appears first on the scapulars, back and breast; and
the tail is the last to appear. The young bird is fully feathered,
except the tail, by the time it is two-thirds grown. In fresh juvenal
plumage the color pattern is much like that of the adult female; the
crown, hind neck, back and wings are brownish black, all the feathers
being edged or tipped with "cinnamon"; the edgings are narrowest on the
head, upper back and wing coverts, and broadest on the scapulars and
tertials; the face, sides of the head and all under parts are white; the
central tail feathers are dusky and the others are white, washed with
dusky near the tip, and all tipped with pinkish buff. This plumage is
worn all through the fall and winter, with no change except by wear and
fading; before winter the edgings have largely disappeared.
A partial prenuptial molt of the body plumage occurs in early spring,
when young birds become indistinguishable from adults, except for some
retained juvenal wing coverts. Adults probably have a partial prenuptial
molt in early spring and a complete postnuptial molt in late summer, but
there are no well marked seasonal differences in plumage.
_Food._--Doctor Wetmore (1925) writes:
Stilts feed by picking up insects on muddy shores or in shallow
water, and though not averse to frequenting alkaline areas, on the
whole prefer fresher water than do avocets. For detailed analysis,
80 stomachs of the black-necked stilt were available, distributed
from March to August, and collected in California, Utah, Florida,
and Porto Rico. Vegetable food in these amounted to only 1.1 per
cent, whereas the animal matter formed 98.9 per cent. The birds are
adept in seizing rapidly moving prey and in general are very
methodical in their manner of obtaining food. Gravel is picked up
to some extent to aid digestion, and part of the seeds taken may
have been swallowed for the same purpose.
The animal food consisted mainly of insects, aquatic bugs and beetles
making up the largest items; dragonfly nymphs, caddisflies, mayfly
nymphs, flies, billbugs, mosquito larvae, and grasshoppers were
included. Crawfishes, snails, and a few tiny fishes were eaten. The
vegetable food consisted mainly of a few seeds of aquatic and marsh
plants.
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