6o BIRD LIFE GLIMPSES 



near where he had gone, and here they were shortly- 

 joined by him. Certainly the rooks were influ- 

 enced by the crow — the crow afterwards by the 

 rooks, I think — but in what way, or whether there 

 was any definite idea on the part of either of them, 

 I am unable to say. Birds of different species often 

 affect one another, psychically, in some way that one 

 cannot quite explain. I have seen some small tits 

 flying, seemingly full of excitement, with the first 

 band of rooks from the roosting-place in the morn- 

 ing, and, evening after evening, a wood-pigeon would 

 beat about amongst the hosts of starlings, which 

 filled the whole sky around their dark little dormi- 

 tory. He would join first one band and then 

 another, seeming to wish to make one of them, and 

 this he continued to do almost as long as the star- 

 lings remained. Peewits, again, seem to have an 

 attraction for starlings, and other such instances, 

 either of mutual or one-sided interest — generally, I 

 think, the latter — may be observed. We need not, 

 I think, assume that every case of commensalism 

 amongst animals has had a utilitarian origin, even 

 when we can now see the link of mutual benefit. 



Rooks, when once introduced, are not birds that 

 can be lightly dismissed. The most interesting 

 thing about them, in my opinion, is their habit of re- 

 pairing daily to their nesting-trees during the winter. 

 Two visits are paid — at least two clearly marked 

 ones — one in the morning, the other in the later 

 afternoon, taking the shortness of the days into 

 consideration. The latter is the longer and more 

 important one, and, to give a general idea of what 

 happens upon it, I will describe the behaviour of 



1 



