86 On the Migration of North American Birds. 



is protected against the influence of the cold. There is another cir- 

 cumstance, with regard to the capacity of birds, to endure cold, 

 which is not generally taken into consideration, it is the high degree 

 of temperature. The temperature of the human body is generally 

 placed at 97 or 98 of Fahrenheit, that of warm blooded, animals two 

 or three degrees higher, and that of birds as high as 106 making a 

 difference of 8 or 9 degrees, between birds and men. A large mass 

 of air penetrates the lungs and all the aerial sacs and canals of the 

 bird, increasing the action of the heart and propelling the tide of cir- 

 culation with great rapidity. The pulsation in birds follow each 

 other in such quick succession that they can scarcely be counted. 

 The heat of their bodies being much greater than that of animals 

 enables them to bear with ease the rigorous cold in the distant north 

 and in the elevated regions of the air. 



Some birds migrate only from one extreme of our union to the 

 other. Thus the many species that go under the name of Sparrows ' 

 that breed at the North, with the exception of three, the Snow, 

 Bunting, {Emberiza nivalis,) the three Sparrows, {Fringilla ar- 

 boreal) and the white crowned bunting,* {Fringilla Leucophrys,) 

 spend their winters in tens of thousands in Carolina. When the 

 meadow Lark, (Sturnus Ludovicianus,) and the brown Lark, (Anthus 

 spinoletta,) find the snows of the north covering the earth, and hi- 

 ding their favorite food, they retreat before it and seek sustenance in 

 our Southern states. Other families of birds, such as feed on ripe 

 berries, that abound in the winter also remain with us : these are 



7 



the Robins, {Tardus migratorius,) the wax bird, {Bombycilla Amer- 

 icana,) and the blue bird, (Saxicola sialis,) which feed on the ber- 

 ries of the Tupelo, (Nyssa aquatica,) the Holly, (Ilex opaca,) the 

 Cassena, {Ilex cassina,) and the small black and red berries of sev- 

 eral species of Smilax and Prinos. The yellow crowned Warbler, 

 {Sylvia coronata,) is the only Sylvia out of fifty species inhabiting 

 the U. States, that remain with us in the winter, and even this bird 

 could not find a subsistence among us were it not that it almost chan- 

 ges its nature in winter and lives on the fruit of the wild myrtle, 

 {Myrica cerifera.) This is also the case with the only fly catcher, 

 that winters in Carolina, the Pewee, (Muscicapa fusca,) which 

 sometimes fattens on the seeds of our imported tallow tree, {Styl- 

 lingia cerifera^ 



* It has been commonly believed, that this very rare species which breed at 

 Labrador, does not migrate far to the south in winter. It however passes through 

 Carolina early in autumn, and winters farther south. 



