tfj. \'^^' 



OSTIAK BOATS 



CHAPTER XLI. 



MIGRATION. 



Climate of the Tundra — Break up of the Ice — Migration of Birds in the 

 South of France — Comparison between Island and Continental Migration — 

 Routes of Migration — Grouse — Conservatism of Birds- — Mortality amongst 

 Migrants — Origin of Migration— Glacial Epochs— Emigration of Birds — - 

 Geographical Distribution of Thrushes — Reports on the Migration of Birds. 



The history of animal and vegetable life on the tundra 

 is a very curious one. For eight months out of the 

 twelve every trace of vegetable life is completely hidden 

 under a blanket six feet thick of snow, which effectually 

 covers every plant and bush — trees there are none to 

 hide. During at least six months of this time animal 

 life is only traceable by the footprints of a reindeer or a 

 fox on the snow, or by the occasional appearance of a 

 raven or a snowy owl, wandering above the limits of 



