Observations on the Cuckoo. 463 
ed it unexpectedly. It died on the 2nd of 
July, the fifth day after it was hatched, and 
then weighed 318 grains. 
Young cuckoos are so very different from 
adults, that they have been described by seve- 
ral authors as a distinct species. In the co- 
lours of their plumage, and in their eyes, they 
bear some resemblance to young kestrils; 
while the old birds, in both these particulars, 
are very similar to the male sparrow-hawk 
after the third or fourth moult. As young 
cuckoos do not acquire their mature plumage 
while they remain in this country, though they 
are sometimes seen here in September, two 
months Jater than old birds, and as they are 
never found in their first feathers on their re- 
turn in spring, they must moult during their 
absence: which clearly proves that they are 
migratory; as it is hardly possible that they 
should acquire fresh feathers in a state of tor- 
pidity. This fact is further corroborated 
by the early departure of the old birds, which 
takes place when the temperature is approach- 
ing the maximum for the year, and, conse- 
quently, when itis much higher than at the 
time of their arrival: and it is evident that 
they cannot become torpid with an increas- 
ing temperature: indeed, the young birds, 
which stay so long after them, instead of dis- 
