EXTRACTS FROM THE FOREIGN PERIODICALS. 271 



Other birds only migrate occasionally and partially, according to the supply 

 of food. The Virginian Partridge, if grain is scarce in New Jersey, 

 crosses the Delaware to proceed to Pensylvania. The flight of these 

 birds is so heavy, that, in general, unable to cross the river, they fall into the 

 water, and complete the journey by swimming. It is the same with the Wild 

 Turkeys, which, when they arrive weary and lean on the other side the Ohio, 

 the Missouri, or the Mississipi, are caught in great numbers. 



It is supposed that the Migratory Pigeons only visit the U. S. in very hard 

 winters. This appears, however, to be erroneous. I have seen immense flights 

 of these birds in Canada in winter, during intense cold, but after a season highly 

 favourable to the grain on which they subsist. It is only the want of this food 

 which compels them to migrate to the south. 



Agricultural improvements, by introducing plants, &c, extend the migrations 

 of birds. Thus the Mocking Wren (Troglodytes Ludovicianus), and other species 

 now common in the northern states, were unknown in the time of Wilson. 

 The Cliff Swallow (H. lunifrons), a Mexican bird, appeared for the first time 

 on the banks of the Ohio, in 1815. It excited great interest by the structure of 

 its mud-built nest, of which several are placed together, and resemble in shape 

 a group of Gourds. Every year it advances in its migrations, which now extend 

 to Canada. The same may be said of many other birds. 



It has been computed, that out of the 450 species known in North America, 

 only 108 are common to the two continents, the water-birds forming more than 

 three-fifths of the number. These species are principally Eagles, Hawks, Owls, 

 and Crows, among land birds, and Ducks or sea-birds among the Aquaticce. 



The most singular notions have been entertained respecting the habits of the 

 Rail. Absent throughout the summer, it suddenly appears in myriads in Au- 

 gust, on the banks of the Delaware. Here they remain till October, when they 

 suddenly disappear, and not one is to be seen where, on the day before, the) 

 were found by hundreds. As their flight is heavy, these birds are supposed to 

 retire in winter to hollow places, or even under the ice. The fact is that they 

 take their departure in the night. They breed very far north, and have been 

 seen on their nests along the marshy lakes of Upper Carolina. 



When the period of departure arrives, birds display a kind of irresistible rest- 

 lessness. Goldwings, Orioles, &c, carried while young to the north, and 

 liberated in spring, fly in the direction of the pole, as if guided by a compass. A 

 little before the approach of winter, and sometimes when the cold weather is 

 already commencing, birds of passage assemble in flocks. The young of most 

 species unite, as if they disdained to inquire the way of their elders. Some fly 

 separate, others in thin scattered troops, and others again in regular flocks. 

 Some fly slowly, and as though affected by the cold ; others proceed rapidly, and 

 achieve their journey in a few days. Some birds fly from land to land, and often 



