170 BEITISH BIEDS 



instinct of the bird not only to have his house far out of reach of 

 all possible terrestrial enemies, but so placed that a wide and unin- 

 terrupted view of earth and sky may be obtained from it. As things 

 now are his winged enemies do him little hurt, but it was not always 

 so. In the next place, the branches must afford a suitable founda- 

 tion to build on : they must be strong, and forked, so as to hold the 

 fabric securely during high winds and sudden violent storms ; fur- 

 thermore, there must be a clear space above or at the side, to 

 enable the bird to approach and leave it without striking against 

 the surrounding boughs. It is a well-known fact that rooks will 

 desert a rookery when the trees are decaying, even when, to a 

 human eye, they appear sound. The most probable explanation 

 which has yet been offered of this fact is, that a considerable 

 amount of pliancy in the branches is necessary for the safety of the 

 nest ; for if the branches do not yield and sway to the force of the 

 wind, the nest is in danger of being blown bodily out of its place : 

 in the decaying tree the upper branches become too stiff, from the 

 insufficient supply of sap. 



The building and repairing time is one of great and incessant 

 excitement in the rookery ; and it is curious to note that birds of 

 such a social disposition, and able to live together in concord at all 

 other times, are at this period extremely contentious. As a rule, 

 when one bird is abroad foraging for sticks, his mate remains on 

 guard at the nest. Among these watchers and the birds that are 

 leaving and arriving there is much loud cawing, which sounds like 

 ' language,' in the slang sense of the word ; and it might appear 

 that they were all at strife, and each one fighting for himself. ]>ut 

 it may be observed that a majority of the birds respect each other's 

 rights, and never come into collision, and that there are others, in 

 most cases a very few, who depart from these traditions, and are, 

 like freebooters, always on the watch to plunder sticks from their 

 neighbours' nests, instead of going afield to gather them. The pre- 

 sence of these objectionable members of the community may account 

 for some of the curious episodes in the life of the rookery as, for 

 instance, the fact that all the birds will sometimes combine to per- 

 secute one pair, and demolish their nest again and again as fast as 

 it is made. 



The nest, when completed, is a large structure, two feet or more 

 in diameter, made of sticks, and lined with dry grass. The eggs 

 are four to six in number, and are bluish green, spotted and 

 blotched with greyish purple and dull brown. 



