54 Trans. Acad. Sci. of St. Louis 



perches on trees or wires as Swallows do ; it alights only 

 on perpendicular walls in holes. On account of its almost 

 incredible rapidity of flight a Swift is of all land birds 

 the most difficult to procure. There is little doubt that a 

 Swift flies usually at the rate of a mile a minute, and 

 since it is on the wing, when with us in summer, at least 

 ten hours, it covers daily a distance of 600 miles, equal 

 to a straight line from St. Louis to New Orleans or to 

 Duluth. Since the distance from New Orleans to Yuca- 

 tan is only 600 miles, a Swift could cross the Gulf of Mex- 

 ico in one night, from 7 p. m. to 5 a. m. 



The bird is only five and one-half inches long, but has 

 a wing spread of twelve and one-half inches. Its color is 

 a sooty brown, darkest on the head and back ; the throat 

 is pale. In flight the tail is folded to a point until a 

 change is made in the direction of the flight, when the ten 

 tail feathers are spread far apart to check the force of 

 motion. In spite of the general resemblance the flight is 

 more steady and free from jerks than that of a Swallow, 

 the wings are used with extremely fast fluttering motion, 

 alternating with only short moments of soaring, and all 

 movements are performed with an abruptness, dis- 

 tinguished from the easy, elegant evolutions of the Swal- 

 low. It is astonishing to see two creatures so little 

 related as Swift and Swallow resemble each other so 

 much, and it shows ''how nature attains the same end in 

 different ways, furnishing similitudes in diversity no less 

 easily than she produces a wealth of diversity from essen- 

 tial unity." 



A bird student can soon tell a Swift from a Swallow in 

 flight at any distance, as he can learn to identify other 

 birds on the wing. This study is interesting and gives 

 much amusement, for we see how different birds move in 

 different ways through the air. Hawks and Vultures 

 spread out their broad wings and sail gracefully and 

 apparently without any effort in straight lines as well 



