fM . LIFE-HISTORIES OF BIRDS 



pursuit of insect prey. When upon the perch or upon the 

 ground, it is quite easily approached : it does not seem to be 

 endowed with that quick perception which warns its nearest 

 kin of the approach of danger. 



Its various and curious evolutions while upon the wing, 

 bear but little resemblance to those of vociferus, being more 

 closely allied to those of the Falconidce. After becoming 

 nearly invisible, it traverses the atmosphere backward and 

 forward like a hawk, remains stationary for a few sec- 

 onds, and then suddenly darts off. producing a peculiar vibra- 

 tory noise by its wings. As it Hies, it is heard to utter n 

 loud and shrill cry which is difficult to express in language, 

 and which seemingly comes from a short distance, when the 

 author is certainly at an immense height. Dr. Richardson 

 likens this sound to that produced by a tense cord set in vi- 

 bration by a sudden gust of wind. This extraordinary and 

 inexplicable sound is mainly produced by the male during 

 the season of courtship, when he has been observed by us 

 to mount to a great height and then tumble head foremost 

 towards the ground* when he would suddenly check his 



O 



descending course. It is at this moment the peculiar boom- 

 ing" is heard. Wilson ascribed its formation to the mouth, 

 but Audtibon was impressed with the belief that it was pro- 

 duced bv the concussion arising from the altered position 

 of the wings. 



The food of these birds consists principally of diurnal and 

 crepuscular insects. The vast abundance of such creatures to 

 be found in the vicinity of large cities, has attracted them 

 thither, where all day long they mav be seen or heard above 

 the crowded streets, in active pursuit of prey. Their bill of 

 fare is quite voluminous. Undoubted remains of the follow- 

 ing insects have been identified in our many stomach-exami- 



r" 



nations: Cetonia inda* Allor/ihia m'tida* Lachnosterna 

 ijucrciiia. /.. tiirticnla. Mdcrodactyla s/(bs/>//tosa* Crato- 

 n\>chus chic re us. I far pal us com par, Pelidnota punctata. 

 among beetles : Tabanus liucola * 7\ ctticttfs. Mii^ca tf<>- 



