NESTLING BIRDS AND WHAT THEY TEACH 259 



and it may well be that these have long since lost the ancestral 

 striping. Many are reared in holes, and in those which lay in 

 open nests the striped pattern of the down would probably 

 afford no protection. 



Among the birds, as in other vertebrate groups, longitudinal 

 stripes do not necessarily give place to a spotted livery, and 

 this to a uniform coloration. In the nestlings of the Emu, 

 Cassowary and Grebe, for example, the striped dress gives 

 place to one without markings, and this again to a patternless 

 plumage in the adult stage. The Game-birds furnish us with 

 two very interesting stages of development. In some, e.g., 

 Quails, the young are striped ; the first pennaceous plumage — 

 as distinct from the downy plumage — may be described as a 

 brown or buff colour relieved by various shades of darker brown 

 arranged in the form of streaks, spots and bars. The adult 

 plumage for both sexes is similar. In others, e.g., many 

 Pheasants, the striped downy plumage is succeeded by a dress 

 resembling the immature and adult dress of the Quails. This 

 dress is retained by the female, but in the male is succeeded by 

 a more or less resplendent livery. In other Pheasants, e.g.. 

 Eared Pheasants {Crossopttlon), the speckled dress of immaturity 

 is discarded by both sexes for one of more or less brilliancy. 



The same order of coloration, which obtains in the life of 

 the individual in one group, is found in another group only 

 in studying the history of the race. This may appear to be 

 only another way of saying that the history of the species is a 

 recapitulation of the history of the race. But in the present 

 connection, it is to be noted, the most primitive species pass 

 through all the possible phases in the course of their growth, 

 while the individuals of the " race " to which we have referred 

 are of comparatively recent origin and have eliminated the 

 earlier phases of development, or have replaced them by new 

 "adaptive" characters. Among the Limicolse, for example, we 

 find striped forms like the Redshank or the Snipe, mottled 

 forms like the Gulls and Terns and some Plovers, and uni- 

 coloured dusky forms like the Skuas and Alcidae, e.g., Guille- 

 mots. In the Terns and Gulls the mottled nestling gives 

 place to a brown first plumage, which is succeeded by a more or 

 less unicoloured adult dress worn by both sexes alike. 



Longitudinal markings occur but rarely among adult birds. 



