18 NORTHERN ZOOLOGY. 



borders of a lake ; or, in districts which do not afford a suitable cliff, it selects for 

 the purpose a lofty, and for the most part a solitary tree. It lays one or two white 

 eggs, and the male, according to the Indians, takes its turn with the female in 

 the work of incubation. When the young ones are hatched, the industry with 

 which the parents provide them with food is often attested by the air being tainted, 

 to a considerable distance from the nest, by the smell of the fish that they are 

 unable to consume. The period of incubation is over by the middle of May ; but 

 the young require the aid of their parents in procuring food until the month of 

 September. 



The Bald Eagle resembles the Golden Eagle in the form of its wings, that are 

 obliquely truncated at the tips, the first feather being short, and the succeeding ones 

 gradually increasing in length to the fourth or fifth, which are the longest ; the 

 remainder diminish successively, but less rapidly than the first ones increase. The 

 wings are otherwise large and powerful, and their rounded form, though it may 

 impair the rapidity of flight in a horizontal line, fits them better for soaring 

 aloft in the atmosphere than the acutely -pointed wings of the true Falcons. The 

 great size of the Eagles seems to render it necessary for them to watch their 

 prey from a height at which they appear to be a mere speck when viewed from 

 below, and they are accordingly endowed with an extraordinary acuteness 

 of vision. So great is the similarity of the Bald Eagle to the Golden Eagle 

 in certain states of plumage, that naturalists of no mean fame, as well as less 

 instructed observers, have often mistaken the one for the other. The par- 

 tially naked tarsi, however, of the Bald Eagle, with the sub-versatile outer toe 

 entirely separated from the middle one, form ready marks of distinction, connected 

 with its habit of seeking its prey in the waters ; and there is also some difference 

 in the form of their bills, that of the Bald Eagle being more rounded on its ridge, 

 with its sides less inclined to each other. It is more difficult to find characters 

 that will serve to distinguish this species from the nearly allied one of the Cinereous 

 Eagle, or A. albicilla, of Europe. The pure white head and tail of the A. leuco- 

 cephala are sufficient to characterize the old bird ; but its young are so like those 

 of the A. albicilla, that Temminck considers the only marked difference to be in 

 the greater length of the tail of the former. On comparing the forms of the bills 

 of living birds of each species, I could observe the margin of the upper mandible 

 of the young A. leucocephala to be more nearly straight, there being only one very 

 obtuse lobe adjoining to the hooked point, whilst in A. albicilla the margin was 

 rendered more undulated by the presence of a second lobe posterior to the prin- 

 cipal one. These differences were, however, very slight even in the birds that 



