MARSH HARRIER. b21 
part of the back of the neck white; others, without the white 
head, have a greyish spot on the throat. Sir Wilham 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 defined 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? 
