the Nestling -Plumage of the Booted Eagle. 137 



brown plumage having been shot from her nest. Previously, 

 however, to the publication of his brochure, MM. Am^d^e 

 Alleon and Jules Vian (' Rev. et Mag. Zool.' p. 342 et seq.) 

 had pointed out that in two instances they had found an adult 

 male mated with a female in immature plumage. If any of 

 these naturalists had thought of leaving the eggs for the time, 

 and revisiting the nests when the young birds were nearly 

 fledged, they would probably have solved the question of the 

 immature plumage of this species. 



Of tlie numerous specimens of both sexes which had come 

 into my possession, many of them shot from the nest, all had 

 exhibited light-coloured underparts, with merely slight varia- 

 tions in the intensity of the striations ; until in 1870 my col- 

 lector at Granada sent to me a pair of Booted Eagles, and the 

 two nestlings which they were in the act of feeding when shot 

 from the nest, on the 20th of June, at Soto de Roma, the 

 Duke of Wellington's estate. The male was in the usual 

 adult plumage ; but the whole of the underparts of iho, female 

 were of a deep coffee-hroion, with darker striations down the 

 shafts of the feathers. This was an interesting stage, and 

 one which I had not hitherto possessed ; but so far it merely 

 conflrmed what MM. Alldon and Vian had already made 

 known as to the female breeding in immature livery. But the 

 plumage of the young birds, which were fully feathered ex- 

 cept that the outer primaries were still in the quill, was most 

 remarkable. The larger of the two had the whole of the 

 undeiparts of a darh hrown, of a somewhat deeper hue than 

 those of the female parent, whilst the smaller nestling had the 

 underparts of a creamy huff, with the usual striations down 

 the shafts of the feathers covering the breast. It would have 

 been more than human virtue, especially in a Spaniard, if my 

 collector had tried to ascertain the sexes of these nestlings by 

 actual dissection and with the hel]) of a microscope ; but from 

 the size there can be no reasonable doubt that the dark brown 

 nestling is the female^ and the light-breasted nestling is the 

 male. 



This variation in the nestlings clears up at once the ap- 

 parent discrepancies in the descriptions of the young. Dr. 

 Jcrdon's young bird was doubtless a male ; and the British- 

 ]\Iuseum bird is a female. In further corroboration of this 

 view, it should be noticed that whilst we have abundant 

 and independent testimony of various females being obtained 

 in this dark plumage, yet there is not on record a single 

 instance of a carefully sexed male with dark brown underparts. 

 The male evidently starts from the nestling stage with light- 

 coloured underparts, and with a plumage almost identical with 



