Our Birds of Prey. 123 
Buteogallus xquinoclialis Busarellus nigricollis 
Heterospizias meridionalis Urubitinga zonura 
Urubitinga anthracina Leucopternis albicollis 
Leucopternis melanops Buteola brachyura 
Buteo albicaudatus Buteo abbreviatus 
„ unicolor 
Pandion halisetus. 
In the identification of these birds, special attention 
must be drawn to the fact that the colouring of the young 
specimens is, in many cases, quite different from that of 
the adult ; and that several apparently distinct birds, as 
judged by mere colouring, can thus often be obtained from 
a series of the same species at different ages — the more 
especially if the sexes be not marked and their characters 
thus confused. The full size of the adult, which is vari- 
able according to the sex of the bird, is soon reached, 
but several moults, or special developments of colour, must 
often take place before the final dress is assumed. The 
changes of tint vary a great deal in the different species, 
and it may be from an early dark colour to a later whiter 
appearance, or the reverse ; though usually brown or 
reddish tints prevail in the young birds, and later give 
place either to black or white or pale bluish-slate. The 
species of Urubitinga, Buteo, Rostrhamus, and Leptodon 
in particular, are noticeable in this respect ; but other 
special cases will be mentioned under the description of 
each form. The characters of the beak and limbs will give 
an indication of the nature of the bird, though to one un- 
familiar with the group, single birds present many difficul- 
ties in their identification which only a series of speci- 
mens of the species, at different ages, can remove. In most 
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