ADAPTATION FOR THE INDIVIDUAL 1 03 



Most of our birds meet this difficulty by changing 

 their base of operations. When the north grows cold 

 these creatures fly to the south. Some of their mi- 

 grations cover enormous stretches of country. Our 

 bobolink, so well known and loved by all watchers 

 of spring migrations, passes twice a year between the 

 latitude of New York and Rio Janeiro. One of our 

 most careful students of bird migration says that the 

 Golden Plover makes, twice each year, the long jour- 

 ney from the Arctic shores of North America to the 

 plains of La Plata. 



Different fur-covered animals have specialized to 

 meet the winter by any one of three different methods. 

 They may brave it out, hunting for their food as best 

 they can all winter long. Such a course is pursued by 

 the rabbit. Again like the squirrel, they may store 

 large quantities of food during the summer, and on 

 this provender they may subsist during winter, re- 

 maining for most of the time near their hiding-places, 

 which, however, they may frequently leave upon 

 warm days. A third method is less common, but very 

 interesting. The groundhog or woodchuck is the 

 best-known example of the group. It remains asleep, 

 or, as it is technically known, dormant, during the 

 winter. This stupor is more profound than ordinary 

 sleep, and from it these animals awaken with diffi- 

 culty. It is needless to remark that the groundhog's 



