d residues in the pellets
collected within each biweekly period were averaged. Also frequency of
occurrence was computed, and maximum and minimum percentages were
included to permit a broader interpretation. In determining the minimum
percentage, only those pellets were considered in which the food residue
was present.

Pellets from roosts of resident crows were collected on a year round
basis in eastern Harvey County near Newton (see tables 1 and 2). The
data from these pellets were interpreted separately from data on
collections made in the western part of the study area from under roosts
of wintering crows (see tables 3 and 4).

In studies of the food of owls analysis of materials in regurgitated
pellets has been widely used, but with crows this method has been little
used because the nature of their food makes identification of material
more difficult. Analysis of pellets has certain merits, however, and, if
closely correlated with field studies, can give valuable information
concerning food habits. The availability of pellets and the ease of
collecting them are obvious advantages. Under large roosts in winter the
number that can be collected is almost unlimited. At other seasons,
pellets are scarcer, but even so they usually are more available than
stomachs.

The technique of pellet analysis is more easily applied to a study of
the yearly diet than is the technique of stomach analysis. The crow is
euryphagous and, as shown by this study, the diets of crows a few miles
apart may differ. Therefore a study made on a limited area within one
biotic community, on a year round basis, and correlated with changes in
the habitat should be of greatest value. For such a study, collection of
stomachs is not practical unless individuals are abundant so that many
can be sacrificed, but collection of pellets is practical and
profitable.

One limitation of data based on material from pellets is the
impossibility of closely correlating the volume of indigestible residues
with the proportion of food items actually eaten. Such correlation is
prevented not only by the different percentages of indigestible residues
in different food items but also by irregularities in regurgitation and
in the efficiency of the crow's digestive system. Barrows and Schwarz
(1895:24-25) cite several instances of such irregularities in captive
crows. In certain pellets that I studied, part of the wheat or other
grain was undigested or partly digested,