WOOD WARBLER 



failures, and quite another to show how the environment can 

 come to possess guiding value for a bird as to its future 

 behaviour. Assuming that the facts are correct, science, I 

 take it, has really no explanation to offer. 1 



The males, when they first arrive, are often more restless 

 and cover a larger area of ground in their wanderings than 

 they are wont to do a few days later. Even upon the first 

 morning of their arrival they do not roam 'far, but confine 

 themselves rather to that particular part of the wood in which 

 they have settled ; afterwards their wanderings become even 

 more curtailed, and the week or so of their bachelor existence 

 is usually passed amongst certain trees on a few acres only 

 of ground. Consequently they own territories after the 

 manner of other species, territories which of course vary in 

 extent according to the nature of the environment and the 

 proximity of rival males, but which, on the whole, are very 

 similar in size to those of the Willow Warbler or Chiff-chaff. 

 One curious departure from the normal routine of behaviour 

 in regard to this question of territory came under my notice. 

 A male that owned a territory in one corner of a large wood 

 was wont to disappear from view for short periods of time. 

 Located in the same wood were a few individuals of the 

 same species, the nearest of which possessed a territory some 

 250 yards away. In order to solve the difficulty of the 

 alternate presence and absence of this particular male I deter- 

 mined to keep him strictly in view for a time, and it soon 

 became evident that he and the neighbouring male referred 

 to were one and the same individual. He therefore owned 

 two territories, in each of which he spent a portion of his 

 time. Unfortunately I was compelled to desert him before 

 any females had arrived, and was unable consequently to see 

 the outcome of his peculiar behaviour. The intermediate 



1 On the hypothesis of germinal variation in every direction, acquired 

 modification may here have determined the survival of variations in the 

 direction of a more complete harmony with the environment in the way 

 suggested by Professor Lloyd Morgan in his principle of the survival of 

 coincident variations. 



7 



