WIGEON. 291 



The whole length eighteen inches. From the carpal 

 joint or point of the wing, to the end of the longest quill- 

 feather, ten inches and a half; the length of the first and 

 second primary quill-feathers nearly equal. 



The adult male birds undergo considerable change in 

 their appearance towards the end of July or the beginning 

 of August, becoming much more uniform in their general 

 colour, losing some of the most conspicuous external dif- 

 ferences which distinguish males from females, and which 

 are to be considered as secondary sexual characters. 



The female Wigeon has the bill bluish-black ; the irides 

 brown ; head and neck brown, tinged with rufous, and 

 speckled with dark brown ; the back varied with two 

 shades of brown, that in the centre of each feather the 

 darkest in colour, the paler brown on the margins tinged 

 with rufous ; quill and tail-feathers as in the male ; under 

 surface of the body nearly white. 



The plumage of the young male birds of the year, for 

 a time, resembles that of the females. 



The tube of the windpipe in the adult male Wigeon is 

 about six inches in length, and nearly equal in diameter 

 throughout ; the form of the bony enlargement and the 

 depending bronchial tubes as figured in the vignette below. 



u2 



