of the United States. 
357 
year, changing the colors of the head only ; the young moult- 
ing continually. Plumage silky, elastic, plentifully supplied 
with down. Colors, including the tail, always pure white, 
with a distinct mantle ; mantle white, pearl-gray, or deep 
slate-black. Young mottled with dull gray and various tints 
of brownish, confusedly spotted, passing by infinite gradations; 
bill, feet and iris, dark ; light in the adult. 
Timid : cowardly except in defending their young. Very 
numerous, covering whole shores. Keep generally in large 
flocks, the young and old separate, the larger species on the 
sea, the smaller along rivers and lakes. Alight on rocks, 
beaches, or on the water. Walk tolerably well : swim with 
ease ; incapable of diving. Keeping much upon the wing ; 
flight rapid, straight, equal, long sustained, even against the 
strongest gales. Contract their neck and draw one foot up 
when resting. Voracious: espying and fighting against 
their own species for prey ; attacking each other without 
any apparent reason. Fall on and devour the wounded. 
Patient of hunger. Feed on every kind of animal food, dead 
or alive, fresh or putrid. Great purgators — sea Vultures; 
the larger species prey on eggs and young birds ; but all prin- 
cipally on fishes, of which they follow the shoals, catching 
them with great agility on the surface of the sea, by darting 
like an arrow, and submerging their head ; digesting scales, 
feathers, and even putrid matter ; when irritated disgorge their 
undigested food. Breed once a year only, principally in desert 
places, Arctic islands, on naked rocks, or on marshy weeds, 
with little preparation : eggs from 2 to 4, generally 3. Young 
leaving the nest soon after exclusion, but hiding carefully, 
and fed for several weeks by their parents. Clamorous : 
voice loud, shrill, often repeated while flying. Flesh tough, 
bad tasted. Feathers valuable. 
Spread all over the world. Species numerous, resembling 
each other greatly in all their different states of plumage. 
Vol. II. 45 
