for so doing. Again, as in the case of the Blackcap, no female was present, the females, as we all know, arriving late.
One more case—this time a Hedge-Sparrow. The male was hopping along a wall in front of the female, carrying a piece of straw, excited, as far as Hedge-Sparrows can be, shuffling his wings and flirting his tail. But, as Mr. Selous aptly remarks, it is the beginning of everything that is fraught with such significance. Is this a non-purposive movement springing out of sexual passion, or is it an outward representation of an idea contained in the bird's mind?
It appears to me that the fact of the male Blackcap and Whitethroat going through this performance before any females had arrived tends to prove that it belongs to the former hypothesis rather than to the latter, and thereby upholds Mr. Selous' theory that this was the origin of the nest. For, watch a Blackcap on his arrival, or any other male before actually having mated, and you will see that his or their movements point to the fact that all the thoughts are concentrated on the one object—the possession of a female—and to attain this object all their powers, chiefly vocal, are directed. Any thought of the construction of a nest—if really there is at all at this period, which I am inclined to doubt—must be in comparison with the other momentous event in the bird's life wholly insignificant. At no time are the vocal powers of the Blackcap shown to such an advantage as when mating; his song then is continuous. When not loud it is a low expressive warbling, and if you will watch him you will see that his whole body is trembling with this nervous excitement. At this time also he puts himself in all kinds of curious contortions. I have seen him carry his tail more than at right angles to his body, which he does at no other period of his life. The same thing may also be said of the Whitethroat, only, in his case, warbling would hardly express his nervous vocal production—it is more of an angry scolding.
Again, the Chiffchaff only floats about the air like a big moth when trying to win a mate. Much the same might be said about the Garden Warbler.
The Marsh-Warbler produces far more vocal variations at this time. The Red-backed Shrike never mimics to such perfection as when mating. I have heard in succession Swallow,
