ON THE MIGRATION OF BIRDS. ae bys 
port Street, Long Acre, four Swallows in moult, in as 
perfect health as any birds ever appeared to -be in 
when moulting.” The plumage of Swifts, from ex- 
posure to the sun and air, loses that deep soot-colour 
which it always has on their arrival, and becomes 
gradually paler till they withdraw. This circumstance 
has not escaped the observation of Mr. White (see his 
‘Nat. Hist. Sel.’ p. 183). The plumage of young 
Cuckoos, Redstarts, and Spotted Flycatchers is very 
different from that of adults. Young Cuckoos have 
the upper parts marked with various shades of brown, 
mixed with black, where the old birds are dove- 
coloured ; and the under parts are pale brown, barred 
with dusky brown, where the old ones are white, 
barred with black; in short, their appearance is in 
many respects so totally different from that of their 
progenitors, that they easily might be, and indeed 
often have been, mistaken for a distinct species. 
Young Redstarts and Spotted Flycatchers have their 
heads, necks, backs, scapulars, &c. spotted; the 
former with pale yellow and the latter with white, 
which is not the case with old birds; and those 
marks which so clearly characterize the sexes of Red- 
starts when their plumage is matured are altogether 
wanting in young birds. Now, as young Cuckoos, 
Redstarts, aud Spotted Flycatchers do not usually 
appear to cast off their nest-feathers before they 
retire, they are readily distinguished from old birds 
while they stay with us; and as birds of these species 
c 
