ROOKERY. 165 



the forest in which the rookery was situated, was 

 covered with bilberries, (vaccinium myrtillus), and as 

 those berries come in at the time when the summer food 

 of the rook is getting scarce, when the covering of the 

 fields diminishes its range, and before the crop can be 

 any assistance to it, they are very much caught at by 

 the rooks ; in like manner as the heath berries are, at 

 about the same season, the chief food of the mountain 

 crows, which, however, as they are not quite so choice 

 either as to the kind or the condition of their food, as 

 the rooks, have a wider range. Though the nest of 

 the crow be pretty closely settled, it is a rude structure, 

 and it is in general placed so high that it vibrates in 

 high winds ; but it appears as if chosen so as that all 

 the twigs with which it is connected may bend equally. 

 This is a general position in those nests that are placed 

 so high in trees, as to vibrate when they are shaken by 

 the winds. One never finds such nests placed between 

 a very slender and a very stiff branch, so as to be de- 

 ranged or crushed by the unequal yielding of the two 

 to the storm. If that were the case, a gale coming in 

 direction of the stiffer one would blow the other apart 

 from it, and the nest would be torn asunder, and a gale 

 from the opposite direction would blow the slender 

 branch against the stiff one, and thereby bruise the 

 nest. Birds that place their nests in an unequal fork 

 of a tree, always place it so far down that there shall 

 not be danger from these causes. The rooks generally 

 choose a situation which is safe in ordinary weather and 

 in brisk gales ; and though they necessarily prefer an 

 aged forest, they are said to evince some tact in avoid- 

 ing decayed branches. As the old ones sit higher in 



