THE BOOK OF MIGRATORY BIRDS 97 



of North America, and ofttimes extend their range to the 

 Azores and Canary Islands. 



II. 



Birds of prey though not calculated to make a pleasing 

 impression on the mind of the observer are objects of 

 utility and interest. They free the countries where they 

 dwell from an immense number of noxious creatures, such 

 as serpents, and some of them at least clear away the 

 carrion. Singing birds devour an innumerable multitude 

 of caterpillars and insects. 



Birds in proportion to their size require much more food 

 than mammiferous animals, and thus become much more 

 useful. Many species of birds serve mankind for food; 

 and their eggs are both nutritious and pleasant. Their 

 plumage serves partly for warmth and partly for ornament. 

 Many delight us with the exquisite modulation of their 

 notes ; nor is our admiration less excited by the skill dis- 

 played in the construction of their nests. 



The migratory habits of various birds are also highly 

 deserving of our notice. Some are only partially migra- 

 tory, removing from one district or locality to another, as 

 from the borders of the sea into the interior of the country, 

 or from the mountains to the plains or vice-versa. Others 

 remove to a distant country, like the stork, which is found 

 in Holland in the summer, but makes its winter abode in 

 Egypt and Barbary. The swallow tribe quit this country 

 and other parts of Europe in the autumn, and pass in 

 large troops over to Africa; they arrive in Senegal early 

 in October. 



But many birds, which among us are birds of passage, 

 are stationary in the milder climate of Palestine, and never 

 leave the place of their birth, unless for a very short time. 

 The number of species of birds is much greater than that 



