52 A NATURAL HISTORY OF THE CUCKOO. 
of the moult being rarely completed in the young of the preceding 
year when they return in spring, one or more of their primary 
quill-feathers, and of the greater coverts impending them, being 
then commonly still unchanged. 
I mention these particulars because it has been intimated, as 
highly probable, from the unusual length and quantity of plumage 
which the Cuckoo carries, that this bird undergoes no change of 
feather during its first winter, but gradually alters in colour only, 
as in some Hawks. 
I have remarked, also, that the adult birds, previously to their 
departure, renew their clothing feathers, and also the tail, but retain 
the quills to bear them on their journey southward. It was in mak- 
ing this observation that I learned additionally that the barred 
markings on the neck of the female recur for a series of years. 
White specimens are sometimes met with, of which one or more 
may be seen in the national collection ; and occasionally a particular 
state of plumage is assumed, more frequently, it would appear, in 
the south of Europe than in our latitudes. The dress alluded to, 
which is very similar to that of the female Kestrel Hawk, bright 
rufous, barred with black, yet different from the immature plumage 
described, has been regarded by Temminck and others as a regular 
progressive stage, common to the whole species ; and to account for 
the comparative infrequency of specimens in this attire northward 
of the Alps and Pyrenees, it has been suggested that the young of 
the preceding year do not migrate so far northward as the older 
birds. The supposition, however, is erroneous; for, even in con- 
finement, I have witnessed the assumption of the grey plumage at 
the first moult ; and it would be contrary to general analogy were 
it otherwise than erroneous, inasmuch as the young of other mi- 
grants return to the place of their nativity the following spring. I 
once saw a specimen, in this particular garb, which had been shot 
in Surrey during May, while in the act of crying ‘ cuckoo,” and I 
am convinced that it is merely an occasional variation, peculiar, how- 
ever, it may be presumed, to the young of the preceding year once 
moulted. 
In its internal anatomy the Cuckoo manifests a close approach to 
the Moth-hunter (or Goat-sucker, as it is sometimes called), and 
appears to be intermediate in its general structure to that curious 
group of birds, and the Tamatias or Puff-birds of South America. 
The skeleton chiefly differs from that of the Moth-hunter in the 
modification of the bill and feet, and in displaying a reduced adapta- 
tion for powerful and sustained flight ; the keel of the breast bone— 
