Adapted Plumage. 151 



There is also towards winter a thickening of the 

 feathers as a defence against the cold. 



A series of careful observations, made under the 

 idea that one cause of migration might be that some 

 birds possessed warmer blood than others, seemed 

 merely to show that birds of powerful flight have a 

 higher blood-heat than less active species. The swift, 

 for example, measured no less than 107 deg. F. ; but 

 that was no more than could be said of the green 

 woodpecker. 



At the approach of winter the oyster-catcher plain 

 enough to be seen at all times with his black and 

 white dress and his bright red beak, as he wanders 

 over the beach at low water, making himself still 

 plainer by his strange cry gets himself a white band 

 across his dusky breast. 



Several of the plovers and sandpipers lose their 

 dark and conspicuous markings. The phalarope, 

 whose summer attire is faced with red, comes to our 

 shores in a delicate suit of white and grey. All these 

 and many other changes, seen at their extreme in the 

 ptarmigan, are no doubt meant as aids to concealment 

 n a bare and wintry landscape. 



The plumage of birds in general, especially of tho?o 

 which make their nests on the ground, will be found 

 to harmonize to a great extent with their usual sur- 

 roundings. The dress of the snipe, for instance, 

 clouded as it is with shades of brown and streaked 

 with markings like a few casual blades of withered 



