SOME THREATENED EXOTIC SPECIES 295 



their kind. The same may be said of the vast 

 colonies of Eider Ducks that are protected for their 

 commercial value. These birds are robbed system- 

 atically of eggs and down each season, and many 

 adults are killed, yet the Eiders do not decrease, for 

 they are always allowed to rear broods, and the 

 slaughter is by no means indiscriminate. Experi- 

 ence thus teaches us that birds would yield supply 

 enough for all reasonable purposes — either for food 

 or plumage — if judicious care were exercised. It 

 is gratifying to know that Egrets are now being 

 kept in captivity for the sake of their plumes. 

 There is, we believe, an establishment near Tunis 

 where these birds are kept and allowed to breed 

 in a large aviary. The plumes are shorn twice in 

 the year, in May and September, each bird furnish- 

 ing about seven grammes in the year, valued at 

 thirty-five francs, a sum, after deducting all ex- 

 penses, which leaves a net gain of some twenty- 

 two francs per bird. This shows how easily we 

 can preserve these beautiful birds from extinction 

 and yet gratify the whim of women for wearing 

 " aigrette." (Conf . Bulletin Soc. Nat. d'Acclim. de 

 France, 1896, p. 102.) 



