MARSH HARKIER. 121 



part of the back of the neck white; others, without the white 

 head, have a greyish spot on the throat. Sir William Jardine 

 describes one as entirely brown, excepting the forehead and 

 back of the head, throat, sides of the mouth, and tips of the 

 quills, which were white; another, pale reddish brown, the upper 

 tail coverts and base of the outer tail feathers pale yellowish 

 red, the former shewing a bar; the back of the head pure 

 white, extending over each eye. 



I have much gratification in communicating the following 

 new theory of what will, I have hardly a doubt, prove to 

 be the fact of the case respecting the striking changes in 

 the plumage of this bird. Mr. Arthur Strickland has written 

 down for me the substance of a previous conversation on the 

 subject, as follows: 'This bird has a regular periodical change 

 of plumage, that has not, as far as I know, been before 

 explained. It begins life in a dark plain brown plumage, with 

 a distinctly denned dark cream-coloured head; it then leaves 

 this country, as it is a regular migratory species; it returns 

 the next spring in a much lighter brindled brown plumage, 

 with a pale orange-coloured head, which pale orange in old 

 specimens extends over part of the neck and shoulders; but 

 in the intermediate time it has undergone a marked change 

 of plumage, losing entirely all portions of the cream-colour 

 of the head, which is in fact only a breeding state of dress. 

 In this winter dress it is of very rare occurrence in this 

 country, but if by chance it does occur, it will be found as 

 above described, in all respects answering the description of 

 the Harpy Hawk of Brisson ; but specimens taken upon their 

 first arrival in spring, may be often got with the cream- 

 coloured head only partly developed.' 



It is a very curious fact that Mr. Arthur Strickland has 

 met with no young birds from the nests in Yorkshire without 

 the white cap on the head, and the Rev. Leonard Jenyns 

 none in Cambridgeshire that had it; and further, in a com- 

 munication to Mr. Allis, Mr. Strickland says that the only 

 adult bird without the white cap he ever saw, was from 

 Cambridgeshire, which is certainly very singular. Can there 

 be two species confounded together? 



