104 BIRDS OF AUSTRALIA. 



of the collections formed at Port Essington, although it doubt- 

 less pays that colony passing visits during its migrations. I 

 believe it will be found that Indian and Australian examples 

 do not differ. It is supposed to have been known to Pallas, 

 and if so, it is the bird described by that author as Hirmtdo 

 ciris. Von Schrenck found it in Amoorland, and it is also said 

 to have once occurred in England. Mr. Jerdon states that it 

 breeds among the huge wall-like crags of the Himalayas, and 

 under the snow- level. 



The keel or breast-bone of this species is more than ordi- 

 narily deep, and the pectoral muscles more developed than in 

 any bird of its weight with which I am acquainted. Its 

 whole form is especially and beautifully adapted for extended 

 flights ; hence it readily passes from one part of the world to 

 another, and, if so disposed, may be engaged in hawking for 

 flies on the continent of Australia at one hour, and in the 

 next be similarly employed in Tasmania. 



So exclusively is this bird a tenant of the air, that I never, 

 in any instance, saw it perch, and but rarely sufficiently near 

 the earth to admit of a successful shot ; it is only late in the 

 evening and during lowery weather that such an object can 

 be accomplished. With the exception of the Crane, it is 

 certainly the most lofty as well as the most vigorous flier of 

 the Australian birds. I have frequently observed in the 

 middle of the hottest days, while lying prostrate on the 

 ground with my eyes directed upwards, the cloudless blue 

 sky peopled at an immense elevation by hundreds of these 

 birds, performing extensive curves and sweeping flights, 

 doubtless attracted thither by the insects that soar aloft 

 during serene weather ; on the contrary, the flocks that visit 

 the more humid climate of Tasmania, necessarily seek their 

 food near the earth. 



The sexes offer no perceptible difference in their outward 

 appearance ; but the female, as is the case with the other 

 memljers of the family, is a trifle smaller than her mate. 



