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NATURE 



[March 25. 1920 



Ostrich Study in South Africa, 

 By Prof. J. E. Duerden. 



THE domestication of the two-toed ostrich in 

 South Africa has rendered available for 

 observation and experiment large numbers of a 

 creature in many respects worthy the attention 

 of zoologists. While this bird's lack of intelligence 

 and absence of any personal recognition may dis- 

 courage the lover of animals who looks for some 

 response for care and attention bestowed, its 

 towering size, wayward strength, and nuptial 

 viciousness yet engender a wholesome regard. 

 The high industrial importance which attaches to 

 its plumage has made necessary an intensive study 

 of the physiological conditions which influence 

 feather growth, as well as of the genetical con- 

 siderations which determine its advance. It is 

 true that, as the foundation of an industry appeal- 

 ing only to adornment and luxury, the bird fell 

 on evil days during the war; but the outlook for 

 the future is now encouraging. 



Though in the wild state the ostrich is one of 

 the most nervous of birds, its instinctive fear of 

 man the unusual can be kept in abeyance on the 

 farm by close association and constant handling 

 from the chick stage onwards, and with intelligent 

 control it is rendered amenable to all the necessary 

 restraints of domestication. Should neglect occur, 

 however, the wild nature asserts itself, and 

 restraint is afterwards impossible, irresponsive as 

 it remains to any "breaking" process. 



During the past fifty years or so the farmer 

 has worked out the main conditions necessary for 

 the production of plumage of the highest excel- 

 lence, without, however, any concern as to the 

 physiological principles involved. As epidermal 

 outgrowths, growing at the rate of a quarter of 

 an inch a day, the unripe plumes are found to 

 be extremely responsive to any variation in the 

 condition of nutrition of the bird. Even the slight 

 difference of blood-pressure between day and night 

 is often found to leave its impress on the growing 

 feather in the form of an alternation of denser 

 and weaker annulations, while, should the bird 

 be in a reduced state, a kinking of the feather 

 sheath at a ring of night growth may result in 

 the formation on the opened plume of the familiar 

 defects known as "bars" (Fig. i). Reduced 

 nutrition may even result in complete stoppage 

 of feather growth, particularly in the case of 

 chicks, a new plume pushing out the old on the 

 restoration of better conditions. Of all parts of 

 the body, epidermal structures seem the first to 

 suffer from insufficient nutrition and to retain a 

 more or less permanent impress of it, as is so 

 often exemplified in nails, hoofs, horns, wool, 

 and hair ; but in the rapidly growing ostrich plume 

 the response appears more manifest, and an 

 economic importance attaches thereto. 



The clipping of the plumes is no more harmful 



to the bird than is the cutting of the hair or the 



trimming of the nails to ourselves. They are 



taken as soon as opened out for fear of deteriora- 



NO.- 2630, VOL. 105] 



tion, while the quills are allowed another two 

 months in which to complete their growth. Several 

 helpful facts are disclosed on the extraction of the 

 quills. Thus, the drawing of the quill invariably 

 serves as a stimulus to the germ below, and the 

 new feather appears at the lip of the socket in 

 about a month's time. All being drawn simul- 

 taneously, a full, even crop of plumes is secured, 

 each regular and perfect in its growth, owing to 

 mutual protection — a great contrast with a crop 

 from a wild or uncared-for bird, which is made 

 up of plumes at all stages of growth as a result 

 of moulting irregularities. Before maturity of 

 plumage is reached, a feather drawn out of time 

 is intermediate in character between those of the 



Fig. I.— Ostrich plumes showing barring defects and sloping bults, results 

 of reduced nutrition. 



plumage before and those coming after. The time 

 of quilling is the most critical of all the operations 

 connected with the farming of the bird, as it 

 determines largely the nature of the succeeding 

 feather crop. The state of nutrition, sexual stage, 

 period of the year, and climatic and food con- 

 ditions have all to be considered. Where only a 

 single clipping annually is secured, adult birds are, 

 if possible, quilled at such a period as will bring 

 the crop to ripeness about the beginning of the 

 breeding season — that is, the middle of winter. 



While the growing plume is highly responsive 

 to changes of nutrition, the farmer soon dis- 

 covered that the response was limited, and that 

 with all his care only certain birds produced 

 superior plumes. As in other domestic animals 

 where much importance is attached to details of 



