10 THE AUD U'B ON! Bia Ei 
Nearly all of these birds were found dead along roads or in fields where 
they had been killed by automobiles or shot. Stomachs were removed, 
opened and their contents, if any, were dried, labeled and stored. Undigested 
remains (parts of invertebrates; fur, feathers and bone) were subsequently 
compared with identified reference specimens in the Illinois State Museum 
(see illustration). We sincerely appreciate the efforts of Dr. J. Alan Holman, 
Illinois State University, Normal, who identified the snake and frog bones 
and Dr. Herbert H. Ross, Illinois Natural History Survey, Urbana, who iden- 
tified certain beetles and moths and confirmed our identifications of other 
insects. 
Contents of an individual stomach do not provide significant informa- 
tion on “typical” or basic predator-prey relationships, for the remains merely 
indicate what one bird in a given locality ate at a given time. Nevertheless, 
the contents do occasionally provide some evidence of prey species that 
may be eaten infrequently and they are often of great interest. One won- 
ders, for example, where and how a Screech Owl managed to catch at least 
45 night-flying moths — did the owl perhaps capture the insects in the man- 
ner of a flycatcher or a Whip-poor-will (on the wing), an event some bird 
students have observed. 
This list of prey species generally fits the dietary habits of the various 
birds outlined in A. C. Bent’s “Life Histories of North American Birds of 
Prey” (1938). As expected, seasonal variations were observed; invertebrates 
(insects, spiders, crustaceans), for example, are largely unavailable during 
the winter. A few prey species recorded here are not frequently found in 
published lists of food items; these include the walking stick insect taken 
by a Screech Owl, and the least weasel taken by a Short-eared Owl. 
STOMACH CONTENTS OF SOME RAPTORIAL BIRDS 
(MINIMUM NUMBERS OF PREY INDICATED) 
COOPER’S HAWK, Accipiter cooperii, 1 stomach 
June, 1954, Hardin Co. — 1 unident. bird. 
RED-TAILED HAWK, Butec jamaicensis, 6 stomachs 
Nov., 1953, McLean Co. — 4 house mice, Mus musculus; 1. prairie vole, Microtus 
ochrogaster. 
March, 1956, Randolph Co. — 2 house mice. 
Nov., 1958, Sangamon Co. — 2 prairie voles; 1 red-legged locust, Melanoplus femur-rubrum; 
4 unident. large grasshoppers, Acrididae (Locustidae). 
Nov., 1959, Pike Co. — 3 least shrews, Cryptotis parva; 1 cottontail rabbit, Sylvilagus flori- 
danus; 1 prairie vole; 4 large grasshopers, Acrididae (Locustidae). 
March, 1962, Washington Co. — 1 cottontail rabbit. 
Nov., 1964, Sangamon Co. — 1 large grasshopper, Acrididae (Locustidae); 1 cottontail 
rabbit. 
RED-SHOULDERED HAWK, Buteo lineatus, 3 stomachs (1 empty) 
Nov., 1953, Pike Co. — 1 juvenile garter snake, Thamnophis sirtalis; 4 small leopard frogs, 
Rana pipiens. 
Jan., 1954, Gallatin Co. — 2 prairie voles; 1 least shrew; 1 unident. beetle, Scarabaeidae. 
