1906.] 



Food of Rooks.' 



413 



The evidence as to the value of the rook as a bird use- 

 ful to agriculture was discussed in a report by Dr. Schleh, 

 of Miinster, which was surnmarized in this 



Food of Rooks. Journal in January, 1905. A later report 

 on the same subject by Dr. Hollrung* 

 of Halle, affords an opportunity of estimating the value of 

 the rook {Corvits fmgiiegus) on the basis of post-mortem 

 examinations made during the past eleven years (i 895-1905). 

 In this period 4,030 rooks were examined, and the various 

 classes of food consumed by them differentiated and identi- 

 fied as nearly as possible. Cereal grains, seeds of other 

 cultivated crops, weeds, and various vegetable remains, to- 

 gether with remains of birds, mice, hares, moles, &c., molluscs, 

 insects, myriapoda, spiders, and so forth, all these were found 

 in numerous instances, insects and vegetable remains, however? 

 being by far the most common. 



The rook is practically omnivorous, though the food taken 

 may be largely influenced by geographical position, weather^ 

 time of year, proximity to lakes, ponds, meadows, &c. In 1902 

 the caterpillars of the winter moth {Cheiniatobia bruinatci) were 

 very plentiful, and in consequence a large number (5,583) were 

 found in the rooks then examined. In spring when the wire- 

 worm was attacking the sprouting corn at the surface of the 

 ground many were eaten by the rooks, but in summer when 

 the wireworms had left the surface few were found. In the 

 month of March 100 rook? were found to have taken 102 

 wireworms, whereas 100 rooks captured between April and 

 September had only taken 40 wireworms. Large numbers of 

 chafer beetles and their larvse, wireworms and elater beetles, 

 weevils, caterpillars, and daddy-long-legs were taken by the 

 rooks. Against this, however, must be put many thousand 

 grains of wheat, barley, and oats, and a considerable number 

 of grains of rye, maize, and buckwheat, as well as potatoes and 

 other crops 



For purposes of comparision, and omitting the less impor- 

 tant items on both sides, we may take the two following tables, 



* Landwirtschaftliche JalD-bikher : Beitrdge zur Bewertung der Saatkrdhe auf 

 Grundvon \ l-ldhrigen Magemin{ersuchjmgen,yox\ Prof. Dr. M. Hollrung, 1906. 



