46 Review of the neiv Continuation 



place when the birds are from nine to fifteen months old, and, 

 as in them, the feathers of the young are characterized by longi- 

 tudinal markings, while those of the adult differ in having the 

 markings disposed transversely. The style of change thus un- 

 dergone may be readily perceived by any one who will take the 

 trouble to procure a nestling Peregrine Falcon, and keep it alive 

 for a year or a year and a half. After this one change, there is 

 no good reason for supposing that the colours of the plumage 

 materially alter at any succeeding moult. Of course, as in all 

 birds, the feathers with time become somewhat bleached or 

 rusty ; but in the autumn of every year these are thrown off, 

 and fresh ones take their place, the same in colour and mark- 

 ings as those originally assumed by the bird at ita first moult *. 

 These considerations being borne in mind, it is always easy 

 to determine, not only whether any given specimen is immature 

 or adult, but also to which of the two forms it may belong. As 

 has just been said, in the young of both birds, the general cha- 

 racter of the markings is that of streaks running along the shaft 

 of the feather, while in the old ones they are as invariably found 

 to be running across the shaft. This is all that is absolutely neces- 

 sary to distinguish between them, though other equally unmis- 

 takeable signs may be observed if looked for. One of these, 

 however — the colour of the cere, legs, and feet, which in the 

 young are bluish or lead-colour, but in the old birds are tinged 

 with yellow — is not always to be trusted in living examples which 

 have been kept long in captivity ; for confinement, and perhaps 

 the want of perfectly fresh food, seems often to interfere with 

 the natural development of colour in those parts. To distin- 

 guish between the two forms can scarcely be said to be more 



* We have said above that Mr. Hancock's opinions are in part founded 

 on repeated observations of living birds in the Zoological Gardens. One 

 of these examples in its mature stage is beautifully figured by Mr. Wolf 

 in the ' Zoological Sketches' (plate 34). When originally brought to the 

 Regent's Park it was said to have been taken in Greenland that year, and 

 its plumage was characterized by longitudinal markings, which, after the 

 first moult, changed into the transverse ones depicted in the drawing. 

 That a change of similar character takes place in the Icelander, Mr. Han- 

 cock, Mr. Nevvcome, and other gentlemen who have kept them in confine- 

 ment, have had many opportunities of observing. 



