92 



Bird-Lore 



All praecocial birds are hatched with a growth of downy feathers 

 which, when they are dry, practically cover their body. 

 Most altricial birds are born essentially naked and do not 

 leave the nest until they have acquired the nestling or 

 Juvenal plumage. There are, however, numerous excep- 

 tions to this statement. For example, many species of the family Alcidae 

 (Puffins, Murrelets, etc.), the Petrels, Herons, Hawks and Owls are 



Condition of 

 Young at 

 Birth 



f'^^. 



JiW||r#^ 



WELL-FORMED NEST OF RED-WINGED BLACKUIRD, AN ALTRiCIAL BIRD 

 (Englewood, N. J., May 30, 1898) 



more or less well covered with feathers at birth, but are then nevertheless 

 comparatively helpless and spend some weeks in the nest. 



The significance of the condition of the young at birth is far-reaching, 

 but, unfortunately, it is not as yet understood. It happens that most of 

 the older or lower forms of birds, — that is, those birds nearest the reptilian 

 type, whence, it is believed, all birds descended, — are praecocial. On the 

 other hand, all the higher birds, that is, those farthest from reptilian 

 ancestors, are altricial. For example, among North American birds the 

 Grebes, Loons, Gulls, Terns, Ducks, Rails, Coots, Snipe, Plover and 

 gallinaceous birds are praecocial, that is, their young run or swim shortly 



