BIRDS AT THEIR BEST 29 



has been lost or has become more or less indistinct. 

 In some cases it is because there was nothing dis- 

 tinctive or in any way attractive in the notes ; in 

 other cases because the images have been covered 

 and obliterated by others — the stronger images of 

 closely-allied species. In the two American families 

 of tyrant-birds and woodhewers, neither of which 

 are songsters, there is in some of the closely-related 

 species a remarkable family resemblance in their 

 voices. Listening to their various cries and calls, 

 the trained ear of the ornithologist can easily dis- 

 tinguish them and identify the species ; but after 

 years the image of the more powerful or the better 

 voices of, say, two or three species in a group of four 

 or five absorb and overcome the others. I cannot 

 find a similar case among British species to illustrate 

 this point, unless it be that of the meadow- and 

 rock-pipit. Strongly as the mind is impressed by 

 the measured tinkling notes of these two songs, 

 emitted as the birds descend to earth, it is not prob- 

 able that any person who had not heard them for 

 a number of years would be able to distinguish or 

 keep them separate in his mind — to hear them in 

 their images as two distinct songs. 



In the case of the good singers in that distant 

 region, I find the voices continue remarkably dis- 



