INTRODUCTORY OBSERVATIONS. 3 



It is very remarkable that while the young of some birds 

 are blind at birth, and remain in the nest until they are fully 

 fledged, those of other birds have their eyes open, and pre- 

 sently leave the nest, being able to run about, and having 

 the instinct of concealing themselves in suitable places. Of 

 the former kind are Vultures, Hawks, Owls, Shrikes, Swal- 

 lows, Flycatchers, Goatsuckers, Thrushes, Woodpeckers, 

 Finches, Pigeons, — in short, all the Aerial and Terrestrial 

 Birds, excepting the Gallinaceous families or Rasores. Among 

 the Grallatores, the Herons and Ibises, and some allied 

 species, alone remain in the nest until fledged ; and among 

 the Sea Birds, the Pelicans, Cormorants, Gannets, Divers, 

 Guillemots, Auks, and allied genera. The young birds which 

 are at once capable of seeing and running are those of the 

 Pheasants, Grouse, Partridges, and other Rasores ; the Bus- 

 tards, Cranes, Plovers, Snipes, Rails, Gallinules, — in short, of 

 all the Grallatores except the Herons and Tantali ; the Gulls, 

 Terns, Albatroses, Petrels, or all the fish-eating swimming 

 birds, except those which dive or plunge after their prey ; 

 and lastly, the young of the whole tribe of Swans and Ducks. 

 Now, here are two series distinct from each other, and we 

 have in the fact a principle of arrangement, to which little 

 attention has been paid, although it is well fitted for the 

 purpose. Certainly no two groups having the opposite cha- 

 racters spoken of can form part of a natural family, and they 

 who have attempted to unite the powerless-younged Pigeons 

 with the active-younged Partridges, have failed in showing 

 that they possess common characters. Yet, as in the other 

 circumstances which distinguish groups there are various gra- 

 dations, analogy would lead us to expect the same in this 

 case ; so that a group, intermediate in characters between 

 two or more groups, may in this respect resemble that to 

 which it is otherwise least allied. 



The mode of nestling, and the form, colouring, and number 

 of the eggs, have not, perhaps, been sufficiently attended to 

 in constructing groups. None of the Grallatorial tribes form 

 very elaborate nests, and most of them merely scrape a cavity, 

 in which they place a few straws. The Herons and Tantali 

 construct a large flat nest, either in trees or on the ground. 



