The Rook. 



[Dec. 



idea as to whether the sum total of the birds' activities are 

 beneficial or injurious from the fruit grower's point of view. 



In short, any system, to be of value, must be open to one 

 interpretation only. It must take into account all the food 

 present in the bird's stomach, crof), &c., and finally it must 

 indicate the ratio which one item of food bears to another. 

 Unless it does this the economic position of a bird cannot be 

 accurately determined. Moreover, by no other method can we 

 obtain the precise and detailed information necessary to enable 

 comparisons to be made of the percentages of the different kinds 

 of food eaten at various seasons of the year and in different 

 districts. 



In uhe light of what has been said, let us turn to a considera- 

 tion of one of our commonest and most plentiful birds, the 

 rook. 



Generally and plentifully distributed throughout the British 

 Isles, there are few of our wild birds better known than this 

 species. Its sociable habits, and the fact that it usually nests 

 in colonies in large trees near to or in the vicinity of human 

 habitation, have all "tended to make it familiar to us. 



The nest, which is usually built about the middle of March, 

 although both earlier and later dates have been recorded, con- 

 sists of twigs sometimes solidified with earth or constructed 

 upon the remains of a nest of the previous season, and is 

 generally lined with grasses, roots, hay, straw, hair, wool and 

 leaves. Three to 5 bluish-green eggs, blotched and streaked 

 with olive -brown, are usuallv laid. Breeding is said to com- 

 mence when the birds are nearly two years old. Both birds 

 assist in sitting the eggs during the 17 or 18 days of incubation, 

 although the major portion of the work seems to fall to the 

 female. The fledging period has been recorded as occupying 

 •29 to 30 days. 



There is good reason to suppose that after the breeding 

 season some of the birds emigrate to the Continent, while 

 towards the end of September and through October and part 

 of November, large numbers arrive on the east coast of Great 

 Britain from Central Europe and Scandinavia, many of them 

 departing in the following February, March, and April. 



There would seem to be a general concensus of opinion that 

 during the past ten or fifteen years the rook has largelj 

 increased in numbers in the British Isles. 



Considerable controversy has taken place for many years past 



