The British Warblbrs. 9 



connotes a species which generally haunts fairly thick covert, 

 into which it slips like magic when disturbed ; it is seldom seen 

 at any considerable height above the ground. 



The more rounded tail connotes a species which has been 

 to some extent modified by environment ; a species which spends 

 a large portion of its life in threaditig its way through dense 

 reed-beds and sedge tangles. A still more rounded tail is that 

 of the Grasshopper Warbler, a bird which I have watched for 

 hours creeping through the thickest undergrowth like a mouse. 

 We obtain a good idea of this type of tail if we imagine that the 

 undergrowth closing behind the passage of the bird has in the 

 course of long ages gradually worn away the tips of the outer 

 rectrices. (I do not say that the tail has actually been modified in 

 this way, though this is conceivable). This type of tail (though 

 carried to a greater extreme) is exemplified by the Bearded Tit, 

 which passes its life in slipping through the stems of the sedge 

 and which will perform the remarkable feat of flitting through a 

 reed bed without striking the reeds. This introduces us to 

 another use of this type of tail, namely, that of instantly altering 

 the line of flight by powerful leverage. Lastly, we come to the 

 forked tail, which connotes a bird which is constantly making 

 rapid darts into the air in pursuit of insects. Every one must 

 have noticed the little "leaf-inspectors" (JPhylloscopi), such as 

 the Chiff-chaff and Willow Wren, ekiug out a scanty subsistence 

 during the cold days of early spring by catching gnats. This 

 type of tail, carried to a further stage of development, is found 

 in the Swallow-like birds. 



Now, inasmuch as the more highly specialized species are 

 always least amenable to domestication, vve should expect to find 

 that the Square-tailed Warblers will do better in a state of cap- 

 tivity than the round- or forked-tailed species, and it is, I think, 

 some confirmation of the above suggestions, that the order of 

 precedence of the species in the above list might almost be 

 accepted as indicating their degree of suitability for cage-life. 

 There are some exceptions, of course; for instance, the Great 

 Reed Warbler is probably a much hardier bird than the Icterine, 

 or Melodious, Warbler, which is not surprising seeing that it is 

 a much larger bird. An old marshman who, long years ago, 



