THE BIRDS AND THE BOOK 5 



refuges are situated on the lower slopes of a 

 volcano, which is always in a state of eruption, 

 and year by year they are being burnt up and 

 obliterated by ashes and lava. 



After I had at once and for ever dropped, 

 for the reasons stated, all idea of a handbook, 

 the thought remained that there was still much 

 to be said about London bird life which might 

 be useful, although in another way. The sub- 

 ject was often in my mind during the summer 

 months of 1896 and 1897, which, for my sins, I 

 was compelled to spend in town. During this 

 wasted and dreary period, when I was often in 

 the parks and open spaces in all parts of London, 

 I was impressed more than I had been before 

 with the changes constantly going on in the 

 character of the bird population of the metro- 

 polis. These changes are not rapid enough to 

 show a marked difference in a space of two or 

 three years ; but when we take a period of 

 fifteen or twenty years, they strike us as really 

 very great. They are the result of the gradual 

 decrease in numbers and final dying out of many 

 of the old-established species, chiefly singing 

 birds, and, at the same time, the appearance of 



