28 Zbe Marbler 



genial or more abundant food, and I am induced to believe that in general 

 the latter is a stronger principle than the former. The small number that 

 remains amidst the snows of the North are either carniverous, such as a few 

 of the Owls, Hawks, the Ravens (Corvus corax), the Canada Jay (Corvus can- 

 adensis) and the Northern Shrike (Lanius boreatis). These pick up a scanty- 

 subsistence by feeding on a few of the smaller birds that remain; or by fol- 

 lowing the hunters and the wolves, and supporting life by picking the bones 

 of the animals which these have left, or they are composed of those birds 

 that feed on the buds of trees, such as the Grouse, that live on the buds of 

 the Birch (Be/u/a), Poplar (Populus), and several species of Willow (SalLx); 

 or those that feed on the seed of the Pine and Spruce, Abies, as the Cross- 

 bill (Curvirosti'a) and Pine Grosbeak {Pyrrhula enuclealor)\ or they are 

 birds that are able to find subsistence on the seeds of plants that are pro- 

 truded above the snow, or on the seeds of grass found in the barn-yards and 

 haystacks of the farmer, such as a few species of the Sparrow. But those 

 immense numbers of birds that feed on insects and worms all migrate to 

 those countries where they are abundantly supplied with this kind of food. 

 These are the Swallows {Hirundo\ the Nighthawks, Whip-poor-wills (Cap- 

 runulgas), the Tanagers [Tangara), the Flycatchers (Muscicapa) and War- 

 blers (Sty/via). To them migration is essential to the support of life. The 

 insects at that season disappear, the earth is bound in frost or covered with 

 snow, and all the means of subsistence are removed; but long ere this these 

 lively tenants of the air have obeyed the impulse of some mysterious prop- 

 erty in their nature and have migrated to more congenial climes. To 

 these may be added all the birds that obtain food from the muddy and moist 

 places of the earth, such as the different species of Curlew (JVume/inis), the 

 Snipes (Scolopax) and the Sand Birds (Trznga), as well as those Ducks that 

 obtain subsistence from fresh water ponds and rivers. These finding the 

 swamps, brooks and shores frozen over migrate from the North to milder re- 

 gions where they can procure suitable food. 



Those birds that migrate but partially and spend their winters in the 

 northern states, though in a milder temperature than their places of sum- 

 mer resort, such as the Eagles, Hawks (Falco), owls (Strix) and Grouse 

 (Tetrad), are enveloped in a warm, thick and downy plumage which in 

 most of the species extends even over the legs and toes. Other birds are ex- 

 posed to the water as well as the cold, such as some species of wild Ducks 

 (Anas), Gulls (Larus), Petrels (Pirocellarta) and Puffins (Puffinus.) These 

 gaining a subsistence from the Sea are not obliged to migrate on account of 

 food. In addition to their warmth of covering which shelters them from 

 the cold, they are supplied with sacs containing an oleagenous substance 

 w ith which they regularly imbricate their feathers, which renders them im- 

 pervious to moisture. Whilst floating on the surface of the water they often 



