142 Observations on Periodical Birds. 
marked with various shades of brown, mix- 
ed 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 pro- 
genitors, that they easily might be, and pro- 
bably often have been mistaken for a distinct 
species. Young redstarts and flycatchers 
have their heads, necks, backs, . scapulars, 
&e., 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 redstarts 
when their plumage is matured, are altogether 
wanting in young birds. Now, as young 
cuckoos, redstarts, and flycatchers, do not 
appear to cast their nest feathers before they 
retire, they are readily distinguished from 
old birds while they stay withus: and as 
birds of these species are never found to retain 
their first feathers on their return in spring, 
they must moult in their absence; and it is 
probable that this may be the case with the 
periodical summer birds generally :* but it is 
perfectly ridiculous to suppose that these 
birds in a state of torpidity, when the animal 
* In this attempt to prove that some of the periodical summer birds 
