196 MY NATURE NOTEBOOK. 



crows, magpies, and jays practically cease to exist 

 wherever game is strictly preserved, because the 

 keepers shoot and trap them without mercy. Thus 

 the missel-thrush, who is a valiant, strong, and selfish 

 bird, finds himself freed from the severest checks 

 upon his multiplication, and thrives to some extent, 

 it is to be feared, at the expense of his weaker, silver- 

 tongued cousin, the song-thrush. 



EBB AND FLOW OF BIRD LIFE. 



One cannot, however, gauge the numbers of the 

 missel-thrushes that will nest with us next spring 

 from their abundance in our garden in winter, because 

 most of these "churr"-ing tyrants of our yew trees 

 and holly bushes are foreigners. Large numbers 

 certainly come over to our shores in autumn ; and, 

 since we must believe that the migration of birds is 

 the result of an ancestral instinct, we have no reason 

 to suppose that it affects foreign members of a species 

 only. In other words, if some missel-thrushes are 

 prompted to fly with the cold wind in autumn, we 

 must presume that all feel the same impulse, and that 

 our own family gatherings of missel-thrushes, which 

 are so common in the fields at the end of summer, 

 find their way to more genial regions, their places 

 being taken by immigrants from north and east. 

 Then, when soft warm winds blow in earliest spring, 

 our own missel-thrushes return, and the foreigners 

 retire. Though as yet the actual facts of bird mi- 

 gration are little understood, this alternate ebb and 

 flow of bird life between winter and summer seems the 

 simplest and most reasonable solution of the problem. 



