30 BULLETIN 621, IT. S. DEPARTMENT OF AGRICULTURE. 



conditions, suffice as evidence. Since stomach analysis falls short in 

 identifying such readily digested food as the tender flesh of young 

 birds, effort was made to secure from reliable observers all possible 

 data bearing on this phase of the crow's food habits. Remains of 

 eggs also are almost certain to escape notice when none of the shell 

 has been eaten, and, in the opinion of some, this factor alone dis- 

 qualifies stomach analysis as a method of investigation for deter- 

 mining the extent of such depredations. It must be borne in mind, 

 however, that even when crows resort- to " sucking " eggs, the shell 

 is at least punctured and small fragments most likely reach the 

 stomach. Even minute quantities of such material are readily 

 identifiable and would seldom escape notice. Eggs up to the size of 

 a robin's will be crushed and swallowed by the crow with almost the 

 entire shell held together by the shell membrane, so that criticisms 

 of this kind must be restricted to cases where larger eggs are eaten. 

 Fragments of these have been found in a sufficient number of 

 stomachs to indicate that crows are in no way averse to eating the 

 shell of eggs, and, in fact, in many cases it appeared as if they took 

 special pains to consume all they found. The writer feels confident 

 that very few instances of egg eating by crows escape notice in 

 stomach analysis. 



The fact that the remains of young birds rapidly disappear when 

 once in the stomach of a crow, and that it is merely the shell of an 

 egg that can be detected and its bulk estimated, has resulted in 

 comparatively small percentages for such items. This circumstance 

 has led to an erroneous impression of the extent and importance of 

 the work. Here, then, is presented a case where the percentage-by- 

 bulk method of estimating bird food must be strengthened by other 

 means of computing the merits of a bird's diet. It is essential that we 

 know the frequency with which crows will resort to such activities, 

 determined by the ratio of the number of stomachs in which wild 

 birds and their eggs were found to the total number examined. It is 

 also of value to know the total number of birds or clutches of eggs 

 eaten by a definite number of crows. This latter information is of 

 greatest importance in passing judgment on the status of nestling 

 crows, where often the remains of a single bird or clutch of eggs is 

 passed around to all members of a brood. To determine the exact 

 number of individuals contained in such a series of stomachs is at 

 best a difficult task and in many instances impossible. 



Wild birds and their eggs comprised 0.32 per cent of the food 

 of the 1,340 adult crows examined. July was the month of greatest 

 consumption, when they formed 1.66 per cent of the food. June was 

 second, with 0.90, and May third, with 0.70 per cent. In no other 

 month did such food amount to as much as one-fourth of 1 per cent, 

 August and October being wholly unrepresented. Wild birds were 



