Food of the Crow, Corvus brachyrhynchos Brehm, in South-central Kansas

Excerpt

Introduction

The yearly diet of the crow was studied from December, 1952, to February, 1954, in Harvey County and the northeastern townships of Reno County, in south-central Kansas. In the United States much attention has been devoted previously to the food taken by the crow because it is of economic importance. The work of Barrows and Schwarz (1895) was the first of a series of studies made by the United States Department of Agriculture. Kalmbach (1918, 1920, 1939) continued these studies by analyzing stomach contents from various parts of the United States. Also he diet of the crow has been studied by local areas (Imler—Oklahoma, 1939; Hering—New York, 1934; Black—Illinois, 1941; Lemaire—Louisiana, 1950).

I am grateful to Dr. Henry S. Fitch, for many valuable suggestions and helpful encouragement given in the course of my study. Professor E. Raymond Hall, who read the manuscript, likewise offered valuable suggestions. Dr. R. L. 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.

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....