206 BIRD LIFE GLIMPSES 



Though upon this and other occasions of the nest- 

 building, the hen chaffinch, alone, has seemed to be 

 the architect, it by no means follows that this is 

 always the case. A process of transition is, as I 

 believe, taking place in this respect with the males 

 of various birds. With the long-tailed tits, for 

 instance, we have just seen how prettily husband 

 and wife can work together ; and that they do so in 

 the great majority of instances, I have little doubt. 

 Yet the first time that I ever watched these birds 

 building, it was only one of the pair who did any- 

 thing ; the other doubtless the male though he 

 came each time with his mate, never brought any- 

 thing with him, and did not once enter the nest. 

 He did not even go very near it, but merely stayed 

 about, in the neighbourhood, till the worker came 

 out, on which the two flew off together. This has 

 been exactly the behaviour of the cock blackbird 

 during nidification, in such cases as have fallen under 

 my observation ; and here I have been a very close 

 watcher, for hours at a time, and for several days in 

 succession. Yet I have, myself, seen the cock flying 

 off with grass, from a field, whilst Mr. Dewar has 

 seen him fly up with some into the ivy on a wall, 

 where a nest was known to be in construction. 

 The cock nightingale attends the hen, when building, 

 in just the same way that the cock blackbird does, 

 but I have not yet seen him take a part in its con- 

 struction. Now to take the blackbird since here 

 we have a clear case of individual difference is it a 

 process of transition from one state of things to 

 another, that we see, or has the transition been made, 

 and are the exceptional instances due to reversion 



