McGregor and Mr. Wilford Hanson provided invaluable
assistance in identification of plants and insects found in
the crow pellets.

Methods

Previous studies were based mostly on analyses of stomach contents. My
study is based on the analysis of 617 regurgitated pellets collected
from roosts and lookout posts. Fifty-three collections of pellets were
made throughout the year at regular intervals, except that none was made
in January, March, or May. The pellets were wrapped individually in
paper or leaves as collected, and each was analyzed separately. The
percentages by bulk of different food residues (excluding sand and other
extraneous material) were estimated in each pellet and recorded.

Description of the Study Area

The study area is on the eastern edge of the Great Bend Prairie
physiographic province of Moore (1930). The climate is characterized by
moderate precipitation (ann. 30"), a wide range of temperature
variations, moderately high wind velocities, and comparatively rapid
evaporation. The summers are generally hot, and the winters are
moderately cold but are free from excessive snowfall. The weather during
the study period was unusually dry, and the summer temperatures were
above normal. A drought had begun in 1952, following the cool and wet
summer of 1951.

The study area includes the zone of transition from bluestem or
tall-grass prairie to the buffalo grass or short-grass prairie. The
principal farm crop in the study area is wheat. Sorghum grain, oats, hay
crops (especially alfalfa), and corn are also grown. The study area
supported a small population of breeding crows; an estimate based on
field observations mainly in eastern Harvey County, was not more than
one pair per square mile. In winter a large population of crows migrates
into the area from the northern Great Plains. Censuses showed that on
parts of the area the feeding population might be as great as 180 birds
per square mile. These wintering crows concentrate in the western part
of the study area where the flat, fertile wheat fields of central Harvey
County are replaced by sand dunes and the sandy Arkansas River Valley.
Here much land is devoted to raising livestock, and sorghum grain is an
important field crop. There is also more waste land there than elsewhere
in the area.

Data From Analysis of Pellets

Data obtained from the analysis of pellets were grouped in biweekly
collections, and percentages of various foo