130 



NATURAL HISTORY 



where they also begin to retire about the 

 hegiiming of Azigtist, 



The great large bat* (which by the by 

 is at present a non-descript in England, and 

 what I have never been able yet to procure) 

 retires or migrates very early in the Sum- 

 mer : it also ranges very high for its food, 

 feeding in a different region of the air ; 

 and that is the reason I never could pro- 

 cure one. Now this is exactly the case 

 with the swifts ; for they take their food in 

 a more exalted region than the other spe- 

 cies, and are very seldom seen hawking for 

 flies near the ground, or over the surface of 

 the water. From hence I would conclude 

 that these hirundines, and the larger bats, 

 are supported by some sorts of high-flying 

 gnats, scarabs, or phalcence, that are of 

 short continuance ; and that the short stay 

 of these strangers is regulated by the defect 

 of their food. 



* The Kttle bat appears almost every month in the 

 year ; bat I have never seen the large ones till the end 

 of April, nor after JuIj/. They are most common in Junej, 

 but never in any plenty : are a rare species with us. 



