212 ANIMALS AT WORK AND PLAY 



to Grinnell Land - - the furthest limit of human as 

 well as of bird migration. 



In summing up his observations, Mr Seebohm 

 declared that the number of birds which go to the 

 Arctic regions to breed is ' vast beyond conception.' 

 They go, not by thousands, but by millions, to rear 

 their young on the tundra. Of the cause which 

 attracts them he was equally certain. It is because 

 nowhere in the world does Nature provide, at the 

 same time and in the same place, ' such a lavish pro- 

 digality of food/ That the barren swamp of the 

 tundra should yield a food supply so great as to 

 tempt birds to make journeys of thousands of miles 

 to rear their young in a land of plenty, only to be 

 found beyond the Arctic circle, seems incredible. Mr 

 Seebohm explained the apparent paradox. The vege- 

 tation largely consists of cranberry, cloudberry, and 

 crowberry bushes. Forced by the perpetual sunshine 

 of the Arctic summer, these bear enormous crops of 

 fruit. But the crop is not ripe until the middle and 

 end of the Arctic summer, and if the fruit-eating 

 birds had to wait until it was ripe they would starve, 

 for, as has been already noted, they arrive on the 

 very day of the melting of the snow. But each 

 year the snow descends on this immense crop of 

 ripe fruit before the birds have time to gather it. 

 It is then preserved beneath the snow, perfectly fresh 



