INTRODUCTION 



miles in extent, which lie upon the surface of the 

 Antarctic seas. (Fig. 4.) 



It is to this mass of floating sea-ice that the 

 Adelie penguins make their way in the autumn, 

 but as their further movements here are at present 

 something of a mystery, the question will be 

 discussed at greater length presently. 



When young and old leave the rookery at the 

 end of the breeding season, the new ice has not yet 

 been formed, and their long journey to the pack 

 has to be made by water, but they are wonderful 

 swimmers and seem to cover the hundreds of miles 

 quite easily. 



Arrived on the pack, the first year's birds remain 

 there for two winters. It is not until after their 

 first moult, the autumn following their departure 

 from the rookery, that they grow the distinguishing 

 mark of the adult, black feathers replacing the 

 white plumage which has hitherto covered the 

 throat. 



The spring following this, and probably every 

 spring for the rest of their lives, they return South 

 to breed, performing their journey, very often, not 

 only by water, but on foot across many miles 

 of frozen sea. 



For those birds who nest in the southernmost 

 8 



