BRITISH WARBLERS 
species, such as the Rook (Corvus frugilegus): these all bear 
witness to the excitement under which the bird labours. 
It seems, therefore, that Nature does exercise an effective 
control over the passions of both sexes of many species in 
this way, t.e., by the necessary condition of the female only 
arising at certain definite times, and in her case this control 
is by some means direct, depending upon internal processes, 
but in the case of the male indirect, though none the less 
adequate. 
The life of the male from the time that the female 
commences to lay is a most methodical one; this seems to be 
the rule of the whole species, and I can nowhere find any 
deviation from it. He adheres with wonderful precision to 
the boundaries of his territory, where he can be seen morning 
after morning in the same tree, pouring out his monotonous 
song, through May, June, and the greater part of July, even 
after the young have left their nest and disappeared—some, 
perhaps, to their winter homes. Not, indeed, till the latter 
part of that month is there any perceptible change, the first 
intimation of which—the approach of the moult—is a gradual 
deterioration of the song. He still, however, keeps to his 
territory until the end of July, when, warned perhaps by the 
inevitable change that is taking place in him, he begins to 
move away and wander into hitherto unexplored land. 
During the whole of this period referred to he lives exclu- 
sively in his territory, and is most jealous of the intrusion 
of any other male, fighting him vigorously, the female even 
joining in the pursuit. As the weeks pass by these combats 
become so frequent, occurring again and again during the 
same morning, that I am inclined to think they are prompted 
largely by a love of play. If this is the case, and they are 
games only, then they are indeed exceptionally vigorous ones, 
differing only in their duration from the fights which take 
place earlier in the season over the possession of the breeding 
territory. There is no doubt about the genuineness of his 
excitement, for on-the approach of the other male he jerks 
18 
