Life histories of North American woodpeckersBent, Arthur Cleveland
Science
Life histories of North American woodpeckers
Bent, Arthur Cleveland
Birds -- North America; Woodpeckers -- North America
We camped within three hundred feet of our first Ivorybill
nest in Louisiana, in 1935. A pair of 24-power binoculars
set on a tripod was trained on the nest opening, and from
daylight, April 10, until 11 a. m., April 14, continuous
observations during the hours of daylight were made either
by the writers or by James Tanner. The nest had been found
the morning of April 6, when the female was incubating, but
how far along incubation had proceeded we made no effort
to determine for fear of disturbing the birds. Contrary
to most published accounts, however, the birds were not
particularly wary and soon became so accustomed to our
presence that they would enter the nest-hole with one of us
standing at the base of the tree and later even when one
of us was descending from a blind which we built on April
9 in the top of an adjacent rock elm, twenty feet distant
from the nest. On April 9, we located a second pair of
Ivorybills in the vicinity of a fresh hole about fifty feet
up in a dead oak, some two miles to the south of the nest
in the maple. The following morning, however, the nest was
occupied by a black squirrel and the birds had disappeared.
Briefly summarizing our five-day vigil at the occupied
nest, we learned that the birds took turns sitting on
the eggs, working in approximately two-hour shifts when
not alarmed, but changing places more frequently when
disturbed. Activities usually commenced about six o’clock
in the morning, three-quarters of an hour after Cardinals
and Carolina Wrens started singing. At this time the female
relieved the male after his having spent the night on the
eggs. Activities ceased about four o’clock in the afternoon
when the male relieved the female on the eggs and went in
the nest for the night. This was nearly three hours before
dark, which came about seven o’clock.
_Eggs._--According to Bendire (1895):
The eggs of the Ivory-billed Woodpecker are pure china
white in color, close grained, and exceedingly glossy, as
if enameled. They vary in shape from an elongate ovate to
a cylindrical ovate, and are more pointed than the eggs of
most of our Woodpeckers. They appear to me to be readily
distinguished from those of the Pileated Woodpecker, some
of which are fully as large. From three to five eggs are
laid to a set, and only one brood is raised in a season.
* * *
The average measurement of thirteen eggs is 34.87 by 25.22
millimetres or about 1.37 by 0.99 inches. The largest egg
measured 36.83 by 26.92 millimetres, or about 1.45 by 1.06
inches; the smallest, 34.54 by 23.62 millimetres, or about
1.36 by 0.93 inches.
The eggs described by Hoyt (1905) measured 1.46 by 1.09 and 1.43 by
1.07 inches in the first set and 1.43 by 1.10 and 1.43 by 1.08 inches
in the second set.
Public-domain text, read in full here on John Shaqi.
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