42 THE CROW FAMILY 



This occurs most often in rookeries placed in exposed positions or 

 containing trees which, like the sycamore and poplars, offer few secure 

 sites for the nest, owing to the way in which the branches project 

 outward from the trunk. In the case of one rookery, it was noted that 

 after a violent storm most nests were blown out of sycamores, two or 

 three out of beech, and none out of ash. The difference between the 

 two latter may, of course, have been due to the position of the trees. 1 

 Statistics given in Mr. G. Muirhead's Birds of Berwickshire go to show 

 that the trees usually preferred are the ash, elm, beech, and Scots fir, 

 of which the first three provide, in the acute upward forking of the 

 boughs, particularly safe sites. If these or any other trees selected 

 show signs of decay, they are deserted promptly, nests and all. Any 

 tree which the rook thus leaves may safely be regarded as doomed. 



When a nest survives the winter, the birds either repair or pull it 

 to pieces, frequently to the last stick, in this case the structure being 

 presumably not worth repair. When little damaged, it may receive 

 additions from year to year, and so become a bulky solid mass of 

 sticks and earth, in which grass, ferns, and even seedling trees may 

 be seen growing, while the recesses in its flanks sometimes provide 

 a nesting place for jackdaws, starlings, or tits. A moment comes, 

 however, when the unwieldy mass is tossed to earth by a hurricane, 

 and the process of growth has to begin over again. 2 



In the work of construction or reconstruction both sexes parti- 

 cipate, but usually one only goes to collect the building material, the 

 other remaining on guard, a very necessary precaution, for rooks, like 

 man himself in primitive society, are unscrupulous thieves, and are 

 sometimes not even deterred by the presence of one or both of the 

 owners from raiding a nest. Hence uproars in the rookery, language, 

 loss of feathers and temper, vengeance, assault, battery, and scattering 

 of sticks. 



The foundations of the nest are usually built of dead sticks, those 



1 Field, 1867, xxix. p. 298. 



2 For a long and fairly exhaustive discussion on the nest-building habits of the rook, see 

 the volumes of the Field for 1806 and 1867. 



I 



