BRITISH WABBLE RS 



ance of the strength of the species? And if territory is an 

 essential to reproduction, and the final appeal for territory is 

 to the strength of the individual male through the law of 

 battle, of what use could it be for females to arrive before 

 males ? On the other hand, if the first step towards reproduc- 

 tion is to find an unpaired male in possession of a territory, 

 what would be the position of a female that, from one cause 

 or another, was late in arriving at the breeding grounds? 

 The balance between these extremes, that is to say, between 

 a too early and too late arrival, must have been gradually 

 adjusted to suit the needs of different species. 



The second observation is that which has reference to the 

 banishment of the young by the parents. It is well known, in 

 the case of many species, that the parents drive away their 

 offspring as soon as they are able to take care of themselves ; 

 and the reasons generally given for this behaviour are, firstly 

 that the supply of food would not be sufficient to maintain 

 both old and young, and secondly, that interbreeding would 

 thus be prevented. While it is no doubt true that both these 

 ends will ultimately be attained, yet neither one nor the other 

 can be the motive force which impels the parent birds to act 

 in so arbitrary a manner, for each would imply an amount of 

 forethought of which no bird is capable. Must we then regard 

 the habit as a chance variation, which, having once arisen at 

 some early stage in the history of bird life, was perpetuated, 

 owing to its having been of some direct benefit to those species 

 possessing it? Or is it not possible that it is linked with 

 some other mode of behaviour ? The latter appears to me to 

 be the more probable alternative, and it is by no means 

 unlikely that it has its origin in, or rather is an extension of, 

 the law of territory. As in so many cases, an interpretation 

 is rendered the more difficult by the fact that the habit is not 

 a universal one, but seems to be confined to certain species 

 only. The Moorhen treats its young, when they are able to 

 find food for themselves, with scant affection, pursuing and 

 pecking them unmercifully, and the Stonechat will not allow 



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