Death-rate in Birds 69 



twice every season, with a single exception, for eight or nine 

 years, ending in 1871, in the ivy on a particular garden 

 wall, and that in each of those years a Cuckoo invariably 

 laid her egg in their second nest " : l and that " the cuckoo 

 never dies " is merely the expression, in proverbial form, 

 of a belief current amongst our forefathers from like 

 observations. Similar experiences might be chronicled 

 almost indefinitely ; and as in at least some of the cases it 

 is impossible to doubt that it is actually the same birds 

 which do return, it follows that the normal life of the adult 

 individual cannot at any rate be a very brief one. This being 

 accepted would seem to compel the admission that the 

 excessive mortality must occur amongst the young birds in 

 their first year. What causes it among birds such as 

 Ravens we know well enough, and the logical inference 

 would seem to be that had a similar persecution been waged 

 against such species as Cuckoos, or Flycatchers, for example, 

 they must have long ago been exterminated. Even with the 

 disappearance of most of their natural enemies, their increase 

 is slow ; but it is steadily proceeding. Many of them have 

 probably never been more numerous than they are to-day, 

 and the headway now being made is probably their first 

 really serious colonisation of the country. The naturalists 

 of future generations may, therefore, be destined to find a 

 British fauna materially different to that now prevailing, 

 due quite as much to the natural increase of some species by 

 reason of the diminution of their enemies as to the dis- 

 appearance, through man's intervention, of others. The 

 only alternative to the excessive death-rate theory would 

 seem to be, either that the majority of the young birds are 

 unable to find their way home again after migration, or that 

 they find more attractive breeding places elsewhere, and 

 there does not seem to be any evidence to support any 

 such assumption. 



Unlike its common relative, the Spotted Flycatcher, the 



Pied Flycatcher has a pleasing song, somewhat resembling 



that of the Redstart, and, like that bird, generally utters it 



from the leafy boughs of a highish tree. The summer 



1 See Yarrell's British Birds, 4th ed., vol. i. p. 403. 



