918 



SCIENCE. 



[N. S. Vol. III. No. 78. 



FOOD OF THE EUROPEAN ROOK (COBVUS 

 FRUGILEGUS). 



An interesting paper upon the food of the 

 Eook, by Dr. Holh-ung, appears in the 

 Seventh Annual Eeport of the Experiment 

 Station at Halle,* and furnishes some points 

 for comparison with the food of our allied 

 species of American birds. 



The following is a list of the principal 

 contents of 131 stomachs of rooks killed in 

 April, May and June : 



48 larvEe of Zahras 22 Tanymecus. 

 (Weevils). 

 gihhus. Snails. 



20 wire worms Mice. 

 (Elaterid larvce). 420 wheat grains. 



253 grub worms. 471 barley grains. 



160 May beetles. 190 oat grains. 



168 8 Otiorynchus 22 cherries. 

 (Weevils). 



From this Dr. Hollrung arrives at the 

 following conclusions : 



" 1. The rooks examined have proved on 

 the whole neither exclusively useful nor ex- 

 clusively injurious. While 25 per cent, of 

 the rooks' stomachs contained no vegetable 

 matter, there were only two cases in 131 

 where no animal matter was found. 



" 2. Their food consisted for the most 

 part (about 66 per cent.) of animal matter, 

 such as mice, larvas of the grain-eating Cara- 

 bid {Zabrus glbbus), grub worms {Melolontha 

 vulgaris)^ dung beetles {Aiyliodius spec.'), and 

 clover weevils (Otiorynchus Ugustici). The 

 vegetable food was made up of wheat, oats 

 and barley and cherries. 



"3. The harm done by the rooks on the 

 one hand was perfectly balanced, and even 

 considerably outweighed on the other hand 

 by the useful services rendered. 



" 4. The rooks feed principally on slowly 

 moving insects." 



The common crow {Corvus mnericanus) 



*Siebenter Jahresbericht ueber die Thiitigkeit der 

 Versuolis-station f iir Pflanzeu schutz zu Halle a. S. 

 1895, Dr. M. Hollrun"-. 



represents, perhaps, in this country, as 

 nearly as may be, the economic position 

 occupied by the rook in Europe, and a 

 few points of comparison in their food may 

 not be without interest. The writer has 

 examined about 900 stomachs of the Ameri- 

 can crow, taken at all times of the j^ear 

 and representing a considerable portion of 

 the United States. Unfortunately Dr. HoU- 

 rung's rooks were all taken in the months 

 of April, May and June, and within a re- 

 stricted area of country, so that the stom- 

 achs probably show a larger percentage of 

 animal food than the average for the whole 

 year. The food of the crow for the same 

 three months contains about the same pro- 

 portion of animal and vegetable matter. 



In the first four items of the above list 

 the crow and the rook present a great simi- 

 larity of taste, the Laehnosferna of this 

 country replacing the Melolontha of Europe. 

 It is in the next two items, the weevils, 

 that the rook shines resplendent. An aver- 

 age of over thirteen specimens of those 

 small but very harmful beetles in each of 

 the 131 stomachs is certainly a splendid 

 showing. The only American bird whose 

 stomach the present writer has examined 

 that can approach this record is the red- 

 winged blackbird (^Agelaius phoeniceus') , 

 which shows a vei-y decided taste for the 

 snout beetle. 



. While many of these beetles were eaten 

 by the crow, they did not constitute so con- 

 stant and important an item as in the case 

 of the rook. The crow eats a considerable 

 number of Carabid beetles, most of which 

 are of the more predaceous species, while 

 those eaten by the rook are for the chief 

 part the larvae of Zabrus gibbus, a very de- 

 structive grain-eating species. Grasshop- 

 pers, which are extensively taken by the 

 crow, are conspicuously absent from the 

 food of the rook. 



In the varieties of vertebrate food the 

 rook is far behind the crow. Only seven- ' 



