Comparative Periods of Nestling Life 11 



duced, at least as far as the tyro is concerned, to a qnes- 

 tion of the sealed or open eye-lids of the young- immediate- 

 ly after it has hatched, and even this may i^rove unreliable 

 in a few instances. It is well known that in most, if not 

 all Nidifugjie, the eyelids separate shortly before the bird 

 is hatched and are wide open almost immediately after 

 birth. Mr. A. B. Howell informs me that according- to his 

 observations all sea birds, except the precocial ones, are 

 hatched with their eyes closed, but that they open within 

 a day or so; just how long he is unable to state. 



The Phavthoiiikhr, Fregatidw, Ardeithe (at least the 

 smaller species : Least Bittern and Green Heron ) ; 

 Cathartichv, some of the smaller Buteon'uhv (Marsh, Coop- 

 er's, Sharp-shinned and Broad-winged Ha^N'ks), Duck Hawk 

 and Goatsucker, open their eyes wide within a day or t\N'o 

 after birth. With most nidicolous birds, however, several 

 days elapse between the separation of the eyelids and when 

 they become wide open. In several instances, on the fourth 

 or fifth day after birth, the eyes of the Mourning Dove, 

 Cuckoo, Horned Lark, Brewer's Blackbird, Hooded Oriole, 

 most Finches and Sparrows, Cedar Waxing, some Yireos, 

 Wood Warblers, Mockers, Wrens, Hermit Thrush and Blue- 

 bird, are wide open. On the sixth or seventh day: Audu- 

 bon's Caracara, some Hummingbirds, Pewee, Blue Jay, Red- 

 eyed Vireo, Chickadee and Rol)in ; eighth day, the Gannet, 

 Belted Kingfisher and Crow ; ninth day, the Purjde Martin ; 

 tenth day, the Flicker; twelfth day, the Great Horned Owl 

 and the fourteenth day the Chimney Swift. 



Newton affirms that the young of nidicolous birds nest- 

 ing on or near the ground in exposed situations, remain 

 in the nest a relatively shorter time than tliose found 

 nesting in less accessible situations. This in general seems 

 to apply to our North American birds as far as known and 

 would seem to infer only an earlier development of the 

 sense of fear and of bipedal locomotion; for though the 

 ground nestling may leave the nest at a relatively earlier 

 age, precocity apparenth' does not extend to the wings 

 or to the ability to care for itself exceptionally early. 

 AVith some exceptions, fear develops almost immediately 



