Hens Assuming Cock Plumage. 159 



neck." The bird was eventually killed about three quarters 

 of a mile from the plantation it was reared in, but in the same 

 wood. The bird was examined at the Field, December 21, 

 1914 ; it was a young hen in complete cock's plumage, with the 

 sexual gland very imperfectly developed. 



Disease of the ovary, attended by the assumption of male 

 plumage by the female pheasant, is a phenomenon that has 

 long attracted the attention of naturalists. It was described 

 by John Hunter in his " Animal Economy," and in the 

 " Philosophical Transactions," vol. Ixx., p. 527, and also by 

 Yarrell. Although gamekeepers frequently speak of the hens 

 thus changed in attire under the title of mule birds, it is now 

 generally accepted that the assumption of male plumage is 

 caused by disease of the ovary, and that the birds exhibiting 

 this change are barren females, not, however, necessarily old 

 birds, as the change of plumage may result from ovarian 

 disease in a hen that has not laid. Exceptions to this rule 

 are, however, given by Mr. J. H. Gurney (Ibis, 1888) as 

 occurring in the merganser, chaffinch, and redstart. The 

 change of plumage takes place to a varying extent, usually 

 beginning with a slight alteration of the neck feathers. In 

 some cases it is absolutely entire, the hen being clothed in 

 perfect masculine plumage, not a single feather of the body 

 remaining unchanged. This singular modification is not con- 

 fined to the common pheasant, but extends doubtless to the 

 whole group. It is recorded as occurring in the Silver Pheasant 

 {Ewplocamus nycthemerus) in the Field of November 13, 1869, 

 and, in the case of a Golden Pheasant hen {Thaumalea picta), 

 given to Mr. Tegetmeier by his friend Mr. Leno, the meta- 

 morphosis was complete. Mr. Leno had this bird in his 

 possession for some years, and had noticed the alteration 

 increasing at each annual moult. A corresponding alteration 

 has been frequently observed in the female of the domestic 

 fowl and occasionally in the grouse, but it is not confined to 

 gallinaceous birds, sometimes occurring in the domestic duck 

 and other orders. That disease of the ovary should cause 



