Life histories of North American wood warblers, Part 1 (of 2)Bent, Arthur Cleveland
Science
Life histories of North American wood warblers, Part 1 (of 2)
Bent, Arthur Cleveland
Birds -- North America; Passeriformes; Wood warblers
the young averaged, when hatched, 1.27 gms.; at one day old, 1.87 gms.;
at two days old, 2.95 gms.; at three days old, 4.36 gms.; at four days
old, 5.57 gms.; at five days old, 7.26 gms.; at six days old, 8.20
gms.; and at seven days old, 8.78 gms. * * *
Of the 168 eggs in forty-one nests, 119 eggs, representing 70.83%,
hatched. Thirty-four eggs, representing 20.24%, disappeared due to wind,
abandonment of nest, and unknown causes. Fifteen eggs, representing
8.93% were addled, two of which were buried with a Cowbird's egg. Of the
119 nestlings, twenty-eight disappeared. This represents 16.66% of all
eggs laid. Four of them were seen dead in the nests. The others
disappeared from unknown causes. Therefore a total of 91 fledglings,
representing 54.17% of the original 168 eggs, left the nest. * * *
After all the young left a nest, the parent birds could be found feeding
them in the immediate vicinity of the nest for a period of about three
days. After this time the birds became more dispersed from the nesting
site, but could still be found in the vicinity for a week or ten days.
An unusual casualty is recorded in the following note sent to me by Dr.
Harrison F. Lewis: "A nest of this species which I found in a
sheep-pasture, was largely built of wool, presumably gathered from the
neighboring bushes, where it had been left by the sheep. One of the
young birds in this nest died as a result of having threads of the wool
in the nest become entangled about its tongue and bill. Another member
of this brood became entangled in a similar fashion, but I released it."
_Plumages._--Dr. Dwight (1900) calls the natal down "mouse-gray," and
describes the juvenal plumage, in which the sexes are alike, as "above,
pale olive-brown. Wings clove-brown broadly edged with bright
olive-yellow paling at tips of the quills, the edge of the outer primary
bright lemon-yellow. Tail pale clove-brown, the inner webs of the
rectrices lemon-yellow, the outer edged with olive-yellow. Below, pale
sulphur-yellow, unstreaked."
The first winter plumage is acquired by a partial postjuvenal molt early
in July that involves the contour plumage and the wing coverts but not
the rest of the wings or the tail. He describes the young male as
"above, pale yellowish olive-green, the edgings of the wing coverts
paler. Below, dull lemon-yellow obscurely, narrowly and sparingly
streaked on the throat and sides with pale chestnut." The female is
paler throughout and has no streaking.
Public-domain text, read in full here on John Shaqi.
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