Life histories of North American woodpeckersBent, Arthur Cleveland
Science
Life histories of North American woodpeckers
Bent, Arthur Cleveland
Birds -- North America; Woodpeckers -- North America
the lowest was located only 58 inches (measured) above
ground and the highest, 15 feet (estimated). * * * No nest
holes of this woodpecker were found in living conifers.
Nor, on the other hand, do the birds seek what is commonly
known as rotten wood, that is, wood too soft for the nest
cavity to be maintained against the incessant wear involved
in the birds’ passage back and forth, incident to the
rearing of a brood. The tree chosen must have been dead a
sufficient length of time for the pitch to have hardened or
to have descended to the base of the tree, and the outer
shell of the tree must still be hard and firm, whereas the
interior must have been softened to a moderate degree by
decay. These conditions are not to be met with in every
standing dead stub; hence the choice of a nest site becomes
a matter of rather fine discrimination.
They found plenty of evidence of this discrimination in the many
unfinished nesting holes of varying depths that had been abandoned,
often several in the same stub. “Some stubs are literally riddled with
holes, these probably recording successive years of occupancy. One stub
had at least 5 fully excavated holes besides 11 or more prospects.
* * * We were led to conclude from all this that the White-headed
Woodpecker is either notional or else very particular, in the selection
of its home. Evidence points strongly to the birds excavating and
occupying a new cavity each year, although one set of eggs was found in
a hole which had been dug in earlier years.”
They made a number of careful measurements of four nests, at heights
varying from about 5 feet to about 10 feet above ground; the internal
dimensions varied somewhat, but the size of the entrance hole was
“surprisingly constant”; in one case this hole was a perfect circle,
43 by 43 millimeters, and in another 37 by 37 millimeters; in the
other two cases the entrance hole measured 47 millimeters in height
and 42 in width; translated into inches this shows a variation in the
two dimensions of from 1.45 to 1.85 inches, which does not seem to be
“surprisingly constant.” The total depth of the cavity varied from 275
to 400 millimeters, or from about 10 to 15 inches.
They say further: “Two of the nest cavities we found were in such
unusual sites as to call forth comment. One at Hazel Green was in a
slanting upright limb on a prostrate dead black oak trunk lying in a
grassy meadow, fully 150 feet from the margin of the forest. The hole
was excavated on the lower side of the stub. The other nest was at
Tamarack Flat, in the butt end of an old log, lifted above the ground
when the tree fell over a granite outcrop. This hole was about 7½ feet
above the ground, and as with the other there were piles of chips
immediately beneath it.”
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account