THE PLUMAGES OF THE OSTRICH. 1 



[With 8 plates.] 



By Prof. J. E. Duerden, M. Sc, Ph. D., A. R. C. S., 



Rhodes University College, Grahamstoicn. 



By the plumage of the ostrich is understood the entire covering of 

 feathers on the bird at any one time. 2 This is not the same at all 

 periods, for the bird varies greatly in appearance between its chick 

 and adult condition, dependent upon differences in the form, color, 

 and other characters of its feathers. Visitors to zoological gardens 

 in other countries, accustomed to seeing only the adult ostrich, would 

 scarcely recognize the same bird in its earlier garb. 



Four well-marked plumages can be distinguished in the ostrich, 

 namely, the natal, the chick, the juvenal, and the adult. These repre- 

 sent four distinct kinds of feather which each feather socket on the 

 bird can produce; but, as regards the bird as a whole, the passage 

 from one stage to another is gradual, as there is no well-defined 

 molting period involving a complete simultaneous change of feathers. 

 Until the adult plumage is reached there is an intermingling or over- 

 lapping of the feathers belonging to different plumage stages, the 

 older feathers being distinguished by their worn and faded appear- 

 ance as contrasted with a freshness and perfection in the newer. 

 Many birds, especially in colder regions, vary the character of their 

 plumage between summer and winter, but the slight seasonal changes 

 of South Africa have scarcely any influence on the feathers of the 

 ostrich, and in the adult there is little or no difference in appearance 

 between summer and winter and a well-defined molting period has 

 not been established. The change from one plumage to the other is 

 dependent upon age and nutrition rather than upon climatic con- 

 siderations. 



1 Reprinted by permission, with corrections by the author, from the Agricultural 

 Journal of the Union of South Africa. Pretoria. Government Printing and Stationery 

 Office. Vol. 1, No. 1, February, 1911. This article is in continuation of a series con- 

 tributed by Dr. Duerden from time to time to the Cape Agricultural Journal. 



2 Among farmers the term plumage is sometimes restricted so as to refer only to the 

 white wing quills. Thus, by an ostrich in " full plumage " is understood one in which 

 the wing plumes are fully developed ; when these have been clipped and the quills only 

 remain a bird is said to be " in quills." Throughout this paper, however, plumage will 

 refer to the covering of feathers as a whole. 



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