Chapter M: P. Skinner writes as follows of this bird nesting in the Yellowstone

National Park:

All the nests I have found were on high, dry land, although
never more than two or three hundred yards from water,
while some were within 20 feet of it. One nest was in a
depression in the meadow grass, but not otherwise lined
or showing any construction. All the other nests were
on knolls or ridges, either on gravel soil or on gray
formation; they were in depressions varying from a shallow
saucer-shaped hollow to one that was 2 inches deep by 3
inches in diameter; and in each case the birds appear
to have taken possession of a previous hollow, although
possibly deepening and otherwise forming it to their
purpose. All nests were unlined, although one had a few
sprays of sage and phlox around the edge and another had a
few shreds of dried and bleached wood scattered about.

John G. Tyler (1913), writing of the nests in Fresno district, California, says:

A typical nest throughout the cultivated sections is
composed of a handful of white pebbles about the size
of peas and very uniform in size, mixed with an equal
number of dry shells of melon seeds of the previous year.
Frequently a few dry, broken-up pieces of melon stems are
used also, the whole being spread out over a space the size
of a saucer, with the eggs resting in the center * * *. On
the summer-fallow fields only a few dry grass blades line
the place where the eggs rest, while around the ponds of
the west side, the eggs generally lie half covered in the
powdered alkali dust without a scrap of nest lining.

W. J. Brown (1916) speaks of finding many attempts at excavating nests in the ground not far from the real nest. He suggests they may be decoy nests. Mrs. Henry W. Nelson (1900) reports a case where the eggs were laid in the bare gravel driveway and were moved by the gardener to the edge of the turf out of the way of carriages. The bird continued to incubate. W. Lee Chambers (1901) relates the case of a killdeer’s nest between the ties on a used railroad track; F. W. Aldrich, of one between double tracks of a well-used railroad, and notes of a similar case to the latter have been sent by F. A. E. Starr.

Gayle Pickwell (1925) found near Lincoln, Nebr., the nest of a killdeer in a rubbish heap of broken glass, old bottles, and other material with which the dark mottled eggs harmonized so closely in color that they were invisible until closely approached. In fact killdeers’ eggs are so protectively colored for the usual surroundings that the instinct of nest concealment by furtive abandonment is exhibited by the killdeer as in the case of most shore birds.

The most unusual case of the nesting of the killdeer is that observed by Mr. Pickwell (1925) in the same locality on the gently sloping tarred and graveled roof of a race-track grandstand, some 50 feet above the ground. The eggs were laid in a slight cup-shaped depression among the crushed stones. Close observation showed that the relative position of the eggs in the nest was changed daily between 10.30 a. m. and 3 p. m., and it was not unusual to find them with their points away from the center of the nest. The young were found on the ground near the building while still but feeble walkers. In what manner the old ones transferred them from the roof was not observed.

_Eggs._--[AUTHOR’S NOTE: The number of eggs in a set is almost always four, but five and three have been found. Mr. Pickwell (1925) says the roof-nesting killdeer “laid at least three clutches of eggs during the season extending from early April to the last of June, and she may have raised two broods.” The eggs are ovate pyriform in shape, usually quite pointed, and they have no gloss. The ground colors vary from “light buff” or “cream color” to “cartridge buff” or “ivory yellow.” They are irregularly spotted, blotched, or scrawled, often quite boldly, with blackish brown or black; some eggs have “sepia” blotches and some a few underlying spots of “pale drab gray.” The measurements of 92 eggs average 36.3 by 26.6 millimeters; the eggs showing the four extremes measure =41.5= by 27, 39.5 by =28= and =33= by =25= millimeters.]

_Young._--The incubation period according to the observations of J. A. Spurrell (1917) is from 24 to 25 days; according to Ira N. Gabrielson (1922) it is 25 days. J. M. Bates (1916) found it to be 26 days and Althea E. Sherman (1916) found that 28 days elapsed between the laying of the last egg and hatching.

Both sexes incubate (F. L. Burns, 1915), and both take care of the young. Robert B. Rockwell (1912) relates the following:

“Mr. [L. J.] Hersey was fortunate enough to see one set of eggs hatch. He says the parent birds carried every bit of shell away from the nest within two hours after the hatching.” As soon as the moisture has dried from the down, the young are on their feet and leave the nest and the parents often lead them to the nearest water. They bob and call at an early age. Althea R. Sherman (1916) had watched a nest very closely from the beginning, but she says of the young: “So protective was their coloration, so adroit was parental management that they were not seen after leaving the nest until they had attained the size of adult house sparrows.” The young often escape notice by lying motionless on the ground. At such times they may sometimes be picked up without showing signs of life.

Both parents play the usual wounded-bird act to beguile the intruder from the eggs or young. The following detailed account by Ira N. Gabrielson (1922) is worth giving here:

It is impossible to approach the nest on foot without
alarming one or other of the birds, as one was always on
guard some distance away. At the appearance of a person
walking, the one on guard would fly in a circle about the
nest, giving the alarm, at the first note of which the one
on the nest ran rapidly until some distance away and then
took wing to join its mate in circling about the intruder.
A man ploughing corn was viewed with absolute indifference
by both birds, the team often passing down the row next
to the nest without disturbing the sitting bird. At an
alarm, however, both birds flew about the field unless
the intruder persisted in approaching the nest. In such
a case one of the birds dropped to the ground near the
person, invariably on the side away from the nest, and
fluttered about apparently in the greatest distress. The
attitude most frequently assumed was as follows: one wing
was held extended over the back, the other beat wildly in
the dust, the tail feathers were spread and the bird lay
flat on the ground, constantly giving a wild alarm note.
This performance continued until the observer came very
near when the bird would rise and run along the ground in a
normal manner or at most with one wing dragging slightly as
long as pursuit was continued. If the observer turned back
toward the nest, however, these actions were immediately
repeated. When the parents had succeeded in luring the
intruder about 100 yards, they seemed satisfied as they
then flew away.